0001564590-21-009871 | 10-K | XBRL Viewer

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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN, INC.
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-36740
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0357827
Entity Address, Address Line One	409 Illinois Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	978-1200
Entity Common Stock, Shares Outstanding		91,560,468
Entity Public Float			$ 2,127.6
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Items 10, 11, 12, 13 and 14 of Part III of this Annual Report on Form 10-K incorporate information by reference from the definitive proxy statement for the registrant’s 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than after 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K.

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 678,393	$ 126,266
Short-term investments	8,144	407,491
Accounts receivable, net ($4,127 and $4,845 from a related party)	41,883	28,455
Inventories	16,530	6,887
Prepaid expenses and other current assets ($889 and $125,210 from related parties)	10,160	133,391
Total current assets	755,110	702,490
Restricted time deposits	2,072	2,072
Long-term investments	244	61,118
Property and equipment, net	33,647	42,743
Finance lease right-of-use assets	29,606	39,602
Equity method investment in unconsolidated variable interest entity	2,728	0
Other assets	3,433	9,372
Total assets	826,840	857,397
Current liabilities:
Accounts payable ($1,118 and $0 to a related party)	24,789	6,088
Accrued and other current liabilities ($24 and $36,883 to a related party)	119,521	83,816
Deferred revenue ($2,907 and $249 to a related party)	6,547	490
Finance lease liabilities, current	12,330	12,351
Total current liabilities	163,187	102,745
Product development obligations	18,697	16,780
Deferred revenue, net of current ($4,636 and $125 to a related party)	138,474	99,449
Finance lease liabilities, non-current	25,391	37,610
Other long-term liabilities	39,642	65,407
Total liabilities	385,391	321,991
Commitments and Contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at December 31, 2020 and 2019	0	0
Common stock, $0.01 par value; 225,000 shares authorized at December 31, 2020 and 2019; 91,441 and 87,657 shares issued and outstanding at December 31, 2020 and 2019	914	877
Additional paid-in capital	1,399,774	1,300,725
Accumulated other comprehensive loss	(4,499)	(747)
Accumulated deficit	(974,011)	(784,720)
Total stockholders’ equity	422,178	516,135
Non-controlling interests	19,271	19,271
Total equity	441,449	535,406
Total liabilities, stockholders’ equity and non-controlling interests	$ 826,840	$ 857,397

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Accounts receivable from related party	$ 4,127	$ 4,845
Prepaid expenses and other current assets from related parties	889	125,210
Accounts payable to related party	1,118	0
Accrued and other current liabilities to related party	24	36,883
Deferred revenue current to related party	2,907	249
Deferred revenue non-current to related party	$ 4,636	$ 125
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	125,000,000	125,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	91,441,000	87,657,000
Common stock, shares outstanding	91,441,000	87,657,000

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 176,319	$ 256,577	$ 212,958
Operating costs and expenses:
Cost of goods sold	$ 8,869	$ 1,147	$ 0
Cost, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Research and development	$ 252,924	$ 209,265	$ 235,839
Selling, general and administrative	106,406	135,479	63,812
Total operating costs and expenses	368,199	345,891	299,651
Loss from operations	(191,880)	(89,314)	(86,693)
Interest and other, net
Interest expense	(2,402)	(2,876)	(10,991)
Investment loss in unconsolidated variable interest entity	(202)	0	0
Interest income and other, net	5,553	15,548	11,568
Total interest and other, net	2,949	12,672	577
Loss before income taxes	(188,931)	(76,642)	(86,116)
Provision for income taxes	360	328	304
Net loss	$ (189,291)	$ (76,970)	$ (86,420)
Net loss per share - basic and diluted	$ (2.11)	$ (0.89)	$ (1.03)
Weighted average number of common shares used to calculate net loss per share - basic and diluted	89,854	86,633	84,062
License Revenue [Member]
Revenue:
Total revenue	$ 14,323	$ 177,086	$ 22,269
Development and Other Revenue [Member]
Revenue:
Total revenue	80,592	114,115	125,913
Product Revenue, Net [Member]
Revenue:
Total revenue	72,498	1,700	0
Drug Product Revenue [Member]
Revenue:
Total revenue	$ 8,906	$ (36,324)	$ 64,776

Consolidated Statements of Operations (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
License and milestone revenue from a related party	$ 14,323	$ 129,405	$ 14,323
Collaboration services and other revenue from a related party	19,174	29,393	20,903
Product revenue from a related party	$ 4,281	$ (36,324)	$ 64,776

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (189,291)	$ (76,970)	$ (86,420)
Other comprehensive income (loss):
Foreign currency translation adjustments (Note 2)	(3,207)	331	771
Available-for-sale investments:
Unrealized gain (loss) on investments, net of tax effect	(545)	592	(7)
Other comprehensive income (loss), net of taxes	(3,752)	923	764
Comprehensive income (loss)	$ (193,043)	$ (76,047)	$ (85,656)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

+ Details

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Other Comprehensive Loss [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance at Dec. 31, 2017	$ 547,738		$ 825		$ 1,160,094		$ (1,795)		$ (630,657)		$ 19,271
Balance (ASU 2016-01 [Member]) at Dec. 31, 2017		$ 0		$ 0		$ 0		$ (1,250)		$ 1,250		$ 0
Balance, Shares at Dec. 31, 2017			82,498,128
Net income (loss)	(86,420)		$ 0		0		0		(86,420)		0
Change in unrealized gain or loss on investments	(7)		0		0		(7)		0		0
Foreign currency translation adjustments	771		0		0		771		0		0
Adjustment to issuance costs for Follow-on Offerings	11		0		11		0		0		0
Shares issued from stock plans, net of payroll taxes paid	14,235		$ 29		14,206		0		0		0
Shares issued from stock plans, net of payroll taxes paid, Shares			2,933,974
Stock-based compensation	52,142		$ 0		52,142		0		0		0
Balance at Dec. 31, 2018	528,470		$ 854		1,226,453		(2,281)		(715,827)		19,271
Balance (ASU 2016-02 [Member]) at Dec. 31, 2018		8,688		0		0		0		8,688		0
Balance (ASU 2018-02 [Member]) at Dec. 31, 2018		$ 0		$ 0		$ 0		$ 611		$ (611)		$ 0
Balance, Shares at Dec. 31, 2018			85,432,102
Net income (loss)	(76,970)		$ 0		0		0		(76,970)		0
Change in unrealized gain or loss on investments	592		0		0		592		0		0
Foreign currency translation adjustments	331		0		0		331		0		0
Shares issued from stock plans, net of payroll taxes paid	7,962		$ 23		7,939		0		0		0
Shares issued from stock plans, net of payroll taxes paid, Shares			2,220,957
Warrants exercised	66		$ 0		66		0		0		0
Warrants exercised, Shares			4,430
Stock-based compensation	66,267		$ 0		66,267		0		0		0
Balance at Dec. 31, 2019	535,406		$ 877		1,300,725		(747)		(784,720)		19,271
Balance, Shares at Dec. 31, 2019			87,657,489
Net income (loss)	(189,291)		$ 0		0		0		(189,291)		0
Change in unrealized gain or loss on investments	(545)		0		0		(545)		0		0
Foreign currency translation adjustments	(3,207)		0		0		(3,207)		0		0
Shares issued from stock plans, net of payroll taxes paid	26,366		$ 37		26,329		0		0		0
Shares issued from stock plans, net of payroll taxes paid, Shares			3,783,144
Stock-based compensation	72,720		$ 0		72,720		0		0		0
Balance at Dec. 31, 2020	$ 441,449		$ 914		$ 1,399,774		$ (4,499)		$ (974,011)		$ 19,271
Balance, Shares at Dec. 31, 2020			91,440,633

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (189,291)	$ (76,970)	$ (86,420)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	11,678	11,147	6,562
Amortization of finance lease right-of-use assets	10,369	10,307	0
Net accretion of discount on investments	103	(3,667)	(42)
Unrealized loss (gain) on equity investments	0	(88)	1,120
Investment loss in unconsolidated variable interest entity	202	0	0
Loss (gain) on disposal of property and equipment	933	(42)	53
Stock-based compensation	72,720	66,267	52,142
Realized foreign currency gain	0	0	(1,074)
Realized loss (gain) on sales of available-for-sale securities	258	0	(87)
Changes in operating assets and liabilities:
Accounts receivable, net ($718, $42,365 and $(43,486) from a related party)	(11,973)	35,229	(55,232)
Inventories	(9,175)	(6,887)	0
Prepaid expenses and other current assets ($124,321, $(125,210) and $0 from a related party)	123,492	(128,598)	(129)
Other assets	6,843	(3,253)	1,090
Accounts payable ($1,118, $0 and $0 from a related party)	17,731	(3,051)	3,630
Accrued and other liabilities ($(36,859), $36,439 and $172 from a related party)	31,048	18,288	5,606
Deferred revenue ($7,169, $(3,137) and $(3,908) from a related party)	45,077	(49,941)	(5,031)
Lease obligations	0	0	32
Accrued interest for finance lease liabilities	(177)	194	0
Other long-term liabilities	(28,236)	52,360	1,636
Net cash provided by (used in) operating activities	81,602	(78,705)	(76,144)
Investing activities
Purchases of property and equipment	(3,994)	(5,762)	(8,020)
Payment made for investment in unconsolidated variable interest entity	(3,896)	0	0
Proceeds from equity transfer of unconsolidated variable interest entity	1,063	0	0
Proceeds from sale of property and equipment	0	7	184
Purchases of available-for-sale securities and term deposit	(8,192)	(411,299)	(576,880)
Proceeds from sales of available-for-sale securities	10,606	0	8,167
Proceeds from maturities of investments	456,900	537,072	54,426
Net cash provided by (used in) investing activities	452,487	120,018	(522,123)
Financing activities
Borrowings under capital lease obligations	0	0	49
Repayments of capital lease obligations	0	0	(6)
Repayments of finance lease liabilities	(12,620)	(11,925)	0
Repayments of lease obligations	(403)	(403)	(403)
Cash paid for payroll taxes on restricted stock unit releases	(11,463)	(12,750)	(15,612)
Proceeds from issuance of common stock	37,829	20,778	29,847
Net cash provided by (used in) financing activities	13,343	(4,300)	13,875
Effect of exchange rate change on cash and cash equivalents	4,695	(5)	(8)
Net increase (decrease) in cash and cash equivalents	552,127	37,008	(584,400)
Total cash and cash equivalents at beginning of period	126,266	89,258	673,658
Total cash and cash equivalents at end of period	678,393	126,266	89,258
Supplemental cash flow information:
Interest payments	135	174	218
Balance in accounts payable and accrued liabilities related to purchases of property and equipment	884	460	276
Deferred offering costs recorded in accounts payable and accrued liabilities	$ 0	$ 0	$ 24

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Cash Flows [Abstract]
Accounts receivable from related party	$ 718	$ 42,365	$ (43,486)
Prepaid expenses and other current assets from related party	124,321	(125,210)	0
Accounts payable from related party	1,118	0	0
Accrued and other liabilities from related party	(36,859)	36,439	172
Deferred revenue from related party	$ 7,169	$ (3,137)	$ (3,908)

The Company

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

The Company

1.	The Company

FibroGen, Inc. (“FibroGen” or the “Company”) is headquartered in San Francisco, California, with subsidiary offices in Beijing and Shanghai, People’s Republic of China (“China”). FibroGen is a leading biopharmaceutical company developing and commercializing a pipeline of first-in-class therapeutics. The Company applies its pioneering expertise in hypoxia-inducible factor (“HIF”) biology, 2-oxoglutarate enzymology, connective tissue growth factor (“CTGF”) biology, and clinical development to advance innovative medicines for the treatment of anemia, fibrotic disease, and cancer.

Roxadustat, FibroGen’s most advanced product, is an oral small molecule inhibitor of HIF prolyl hydroxylase activity that has received marketing authorization in China (tradename: 爱瑞卓^®) for the treatment of anemia caused by chronic kidney disease (“CKD”) in dialysis and non-dialysis patients. EVRENZO® (roxadustat) is also approved in Japan and Chile for the treatment of anemia associated with CKD in dialysis and non-dialysis patients.

The Company’s New Drug Application (“NDA”) filing in the United States (“U.S.”) for roxadustat for the treatment of anemia in dialysis and non-dialysis CKD patients was submitted in December 2019 to the U.S. Food and Drug Administration (“FDA”). In December 2020, the FDA extended the review period of the NDA by three months for FibroGen to submit additional analyses of existing roxadustat clinical data, and set a new Prescription Drug User Fee Act goal date of March 20, 2021. On March 1, 2021, the FDA informed us that the Cardiovascular and Renal Drugs Advisory Committee will hold an advisory committee meeting to review the NDA for roxadustat. The date of the advisory committee meeting has not been set. As a result of this communication, we will not receive an approval decision by the PDUFA goal date. In Europe, the Marketing Authorization Application (“MAA”) filing for roxadustat for the treatment of anemia in dialysis and non-dialysis CKD patients was accepted for regulatory review by the European Medicines Agency (“EMA”) in May 2020 and Astellas expects an approval decision by the EMA mid-2021.

Roxadustat is in Phase 3 clinical development in the U.S. and Europe and in Phase 3 development in China for anemia associated with myelodysplastic syndromes. Roxadustat is in Phase 2 clinical development for chemotherapy-induced anemia.

Pamrevlumab, an anti-CTGF human monoclonal antibody, is in Phase 3 clinical development for the treatment of idiopathic pulmonary fibrosis, locally advanced unresectable pancreatic cancer and Duchenne muscular dystrophy.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”). The consolidated financial statements include the accounts of the Company, its wholly owned subsidiaries and its majority-owned subsidiaries, FibroGen Europe and FibroGen China Anemia Holdings, Ltd. (“FibroGen Cayman”). All inter-company transactions and balances have been eliminated in consolidation. For any variable interest entity for which FibroGen is not the primary beneficiary, the Company uses the equity method of accounting.

The Company operates in one segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs.

Variable Interest Entity

Under the Accounting Standards Codification (“ASC”) 810, Consolidation (“ASC 810”), when the Company obtains an economic interest in an entity, it evaluates the entity to determine if it should be deemed a variable interest entity (“VIE”), and, if so, whether the Company is the primary beneficiary and is therefore required to consolidate the VIE, based on significant judgment whether the Company (i) has the power to direct the activities that most significantly impact the economic performance of the VIE and (ii) has the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE.

On an ongoing basis, the Company re-evaluates the VIE assessment based on potential changes in facts and circumstances, including but not limited to, the shareholder loans to the entity and the execution of any future significant agreements between the entity and its shareholders and/or other third parties.

Foreign Currency Translation

The reporting currency of the Company and its subsidiaries is the U.S. dollar.

The functional currency of FibroGen Europe is the Euro. The assets and liabilities of FibroGen Europe are translated to U.S. dollars at exchange rates in effect at the balance sheet date. All income statement accounts are translated at monthly average exchange rates. Resulting foreign currency translation adjustments are recorded directly in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity.

Prior to April 1, 2020, the functional currency of the Company’s subsidiary, FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), was the U.S. dollar. Accordingly, monetary assets and liabilities of FibroGen Beijing in the currencies other than U.S. dollar were remeasured using exchange rates in effect at the end of the period. Revenues and costs in its local currency, Renminbi Yuan (“CNY”), were remeasured using average exchange rates for the period, except for costs related to those balance sheet items that were remeasured using historical exchange rates. The resulting remeasurement gains and losses were included within interest income and other, net in the consolidated statements of operations as incurred.

On April 1, 2020, FibroGen Beijing adopted CNY as its functional currency based on reassessment of the primary economic operational environment of FibroGen Beijing that is mainly associated with its growing manufacturing and product sales activities conducted in CNY. As such, monetary assets and liabilities of FibroGen Beijing in currencies other than CNY are remeasured using exchange rates in effect at the end of the period. The assets and liabilities of FibroGen Beijing are translated to U.S. dollars at exchange rates in effect at the balance sheet date. All income statement accounts are translated at monthly average exchange rates. Resulting foreign currency translation adjustments are recorded directly in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. This change in FibroGen Beijing’s functional currency was accounted for prospectively from April 1, 2020, and the prior consolidated financial statements were not restated. The related currency translation adjustment was $1.3 million at April 1, 2020 upon adoption.

The functional currency of FibroGen, Inc. and all other subsidiaries is the U.S. dollar. Accordingly, monetary assets and liabilities in the non-functional currency of these subsidiaries are remeasured using exchange rates in effect at the end of the period. Revenues and costs in local currency are remeasured using average exchange rates for the period, except for costs related to those balance sheet items that are remeasured using historical exchange rates. The resulting remeasurement gains and losses are included within interest income and other, net in the consolidated statements of operations as incurred and have not been material for all periods presented.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include valuation and recognition of revenue. On an ongoing basis, management reviews these estimates and assumptions. Changes in facts and circumstances may alter such estimates and actual results could differ from those estimates.

Concentration of Credit Risk

The Company is subject to risks associated with concentration of credit for cash and cash equivalents. Outside of short-term operating needs, the majority of cash on hand is invested in U.S. treasuries and money market funds. Any remaining cash is deposited with major financial institutions in the U.S., Finland, China and the Cayman Islands. At times, such deposits may be in excess of insured limits. The Company has not experienced any loss on its deposits of cash and cash equivalents. Included in current assets are significant balances of accounts receivable as follows:

	December 31,
	2020			2019
Astellas Pharma Inc. (“Astellas”)—Related party		10	%		17	%
AstraZeneca AB (“AstraZeneca”)		26	%		81	%

The Company started selling roxadustat in China since late 2019 through a growing number of pharmaceutical distributors located in China. As of December 31, 2019, the aggregate accounts receivable from distributors was immaterial. As of December 31, 2020, along with the growing roxadustat sales in China, the aggregate accounts receivable from distributors represented 64% of the consolidated accounts receivable, with no material balance from any individual distributor.

Other Risks and Uncertainties

The Company’s business is subject to risks and uncertainties, including those related to COVID-19 and the related shelter-in-place, stay-at-home and other similar governmental orders issued in response to the COVID-19 pandemic.

The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, rapid technological change, obtaining second source suppliers, regulatory approval from the FDA or other regulatory authorities, the results of clinical trials and the achievement of milestones, market acceptance of the Company’s product candidates, competition from other products and larger companies, protection of proprietary technology, strategic relationships and dependence on key individuals.

Starting in the first quarter of 2020, the Company experienced slower enrollment in its clinical trials due to the interruption caused by COVID-19 in the worldwide healthcare system. The future impact of the COVID-19 pandemic on the Company’s business is highly uncertain and difficult to predict. The COVID-19 pandemic may continue to affect enrollment in and initiation of the Company’s clinical trials, and could affect the Company’s supply chain if further social distancing and other business restrictions are put in place by various government entities, particularly in China and the U.S. COVID-19 may affect the health of the Company’s employees limiting the Company’s productivity. The COVID-19 pandemic may also impact the market for the Company’s products and product candidates in the future, affecting sales of the Company’s products. Such possible risks and uncertain impacts from the COVID-19 pandemic could have a material adverse effect on the Company’s drug development, commercialization revenues, and other portions of its business, and in particular, could impact the Company’s assumptions of accounts receivable collectability, fair value measurements of investments, liquidity, and development costs. The extent of the pandemic’s effect on the Company’s operational and financial performance will depend in large part on future developments, particularly with respect to the scope and severity of the pandemic, governmental restrictions put in place to fight the pandemic, and the development of vaccines and treatments for COVID-19. Due to the inherent uncertainty of the unprecedented and rapidly evolving situation, the Company is unable to estimate the likely impact of the COVID-19 pandemic on its future operations.

Cash, Cash Equivalents and Restricted Time Deposits

The Company considers all highly liquid investments with maturities of three months or less and that are used in the Company’s cash management activities at the date of purchase to be cash equivalents. Cash and cash equivalents also include money market accounts and various deposit accounts. Restricted time deposits include an irrevocable standby letter of credit as security deposit for a long-term property lease with the Company’s landlord. Restricted time deposits as of December 31, 2020 and 2019 totaled $2.1 million and $2.1 million, respectively. As of December 31, 2020 and 2019, a total of $66.0 million and $11.9 million, respectively, of the Company’s cash and cash equivalents was held outside of the U.S. in the Company’s foreign subsidiaries to be used primarily for the Company’s China operations.

Investments

As of December 31, 2020, the Company’s investments consist of diversified bond funds and marketable equity investments. Those investments with original maturities of greater than three months and remaining maturities of less than 12 months (365 days) are considered short-term investments. Those investments with maturities greater than 12 months (365 days) from the balance sheet date are considered long-term investments. When such investments are held, the Company’s investments classified as available-for-sale are recorded at fair value based upon quoted market prices at period end. Unrealized gains and losses for available-for-sale debt investments that are deemed temporary in nature are recorded in accumulated other comprehensive income (loss) as a separate component of stockholder’ equity. Marketable equity securities are equity securities with readily determinable fair value, and are measured and recorded at fair value. Realized and unrealized gains or losses resulting from changes in value and sale of the Company’s marketable equity investments are recorded in other income (expenses) in the consolidated statement of operations.

A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Premiums and discounts are amortized (accreted) over the life of the related security as an adjustment to its yield. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of investments sold.

Fair Value of Financial Instruments

Carrying amounts of certain of the Company’s financial instruments including cash equivalents, investments, receivables, accounts payable and accrued liabilities approximate fair value (refer to Note 5, Fair Value Measurements).

Trade accounts receivable

The allowance for doubtful accounts is based on the Company’s assessment of the collectability of customer accounts. The Company makes estimates of expected credit losses for the allowance for doubtful accounts by considering factors such as historical experience, credit quality, the age of the accounts receivable balances, current economic and regulatory conditions that may affect a customer’s ability to pay, and estimates of expected future losses. The Company’s bad debt expense for the years ended December 31, 2020, 2019 and 2018 and the allowance for doubtful accounts as of December 31, 2020 and 2019 were immaterial.

Credit losses – Available-for-sale debt securities

The Company periodically assesses its available-for-sale investments for other-than-temporary impairment. For debt securities in an unrealized loss position, the Company first considers its intent to sell, or whether it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis. If either of these criteria are met, the amortized cost basis of such debt securities is written down to fair value through interest and other, net.

For debt securities in an unrealized loss position that do not meet the aforementioned criteria, the Company assesses whether the decline in the fair value of such debt securities has resulted from credit losses or other factors. The Company considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the securities, among other factors. If this assessment indicates that a credit loss may exist, the Company then compares the present value of cash flows expected to be collected from such securities to their amortized cost basis. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded through interest and other, net, limited by the amount that the fair value is less than the amortized cost basis. Any additional impairment not recorded through an allowance for credit losses is recognized in other comprehensive income.

Changes in the allowance for credit losses are recorded as provision for, or reversal of, credit loss expense. Losses are charged against the allowance when the Company believes that an available-for-sale security is confirmed uncollectable or when either of the criteria regarding intent or requirement to sell is met.

Inventories

Inventories are stated at the lower of cost or net realizable value, on a first-in, first-out, or FIFO, basis. The cost of the Company’s inventories in China is determined using full absorption and standard costing method. The Company reviews the standard cost of raw materials, work-in-process and finished goods annually and more often as appropriate to ensure that its inventories approximate current actual cost. The cost of the Company’s inventories in the U.S. uses actual costs to determine its cost basis. The cost of inventories includes direct material cost, direct labor and manufacturing overhead.

When the technical feasibility of the Company’s future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, the Company capitalizes pre-launch inventory costs prior to regulatory approval. A number of factors are considered, including the status in the validation process in significant jurisdictions, regulatory application and approval process, and terms and condition for future sale of such inventory or future alternative use. The pre-launch inventory cost includes purchase cost of raw materials, cost paid to contract manufacturers for inventory manufacturing, freight and custom charges, and certain direct internal labor and overhead expenses.

The Company periodically reviews its inventories to identify obsolete, slow-moving, excess or otherwise unsaleable items. If obsolete, excess or unsaleable items are observed and there are no alternate uses for the inventory, an inventory valuation adjustment is recorded through a charge to cost of goods sold on the Company’s consolidated statements of operations. The establishment of inventory valuation reserves, together with the calculation of the amount of such reserves, requires judgment including consideration of many factors, such as estimates of future product demand and product expiration period, among others.

Property and Equipment

Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight-line method. Computer equipment, laboratory equipment, machinery and furniture and fixtures are depreciated over three to five years. Leasehold improvements are recorded at cost and amortized over the term of the lease or their useful life, whichever is shorter.

Leases

The Company determines if an arrangement is or contains a lease at inception date when it is given control of the underlying assets. The Company elected the practical expedient not to apply the lease recognition and measurement requirements to short-term leases, which is any lease with a term of 12 months or less as of the commencement date that does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise.

The Company’s building leases previously accounted for as build-to-suit arrangements prior to the adoption of Accounting Standards Codification (“ASC”) 842 - Leases (“ASC 842”) are accounted for as finance leases under the requirements of ASC 842.

Lease right-of-use (“ROU”) assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As its leases do not typically provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The Company reassesses the incremental borrowing rate periodically for application to any new leases or lease modifications, which approximates the rate at which the Company would borrow, on a secured basis, in the country where the lease was executed.

Lease ROU assets include any lease payments made and initial direct costs incurred. The Company has lease agreements with lease and non-lease components. The Company generally accounts for each lease component separately from the non-lease components, and excludes all non-lease components from the calculation of minimum lease payments in measuring the ROU asset and lease liability.

The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease terms.

Regarding leases denominated in a foreign currency, the related ROU assets and the corresponding ROU asset amortization costs are remeasured using the exchange rate in effect at the date of initial recognition; the related lease liabilities are remeasured using the exchange rate in effect at the end of the reporting period; the lease costs and interest expenses related to lease liability accretion are remeasured using average exchange rates for the reporting period.

Finance leases are included in finance lease ROU assets, finance lease liabilities, current and non-current on the Company’s consolidated balance sheets. Operating leases are included in other assets, accrued and other current liabilities, and other long-term liabilities on the Company’s consolidated balance sheets.

Impairment of Long-Lived Assets

The Company continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of its long-lived assets may warrant revision or that the carrying value of these assets may be impaired. If the Company determines that an impairment trigger has been met, the Company evaluates the realizability of its long-lived assets based on a comparison of projected undiscounted cash flows from use and eventual disposition with the carrying value of the related asset. Any write-downs (which are measured based on the difference between the fair value and the carrying value of the asset) are treated as permanent reductions in the carrying amount of the assets (asset group). Based on this evaluation, the Company believes that, as of each of the balance sheet dates presented, none of the Company’s long-lived assets were impaired. The Company’s impairment of long-lived assets for the years ended December 31, 2020, 2019 and 2018 were immaterial.

Revenue Recognition

Revenues under collaboration agreements

The Company’s collaboration agreements include multiple performance obligations comprised of promised services, or bundles of services, that are distinct. Services that are not distinct are combined with other services in the agreement until they form a distinct bundle of services. The Company’s process for identifying performance obligations and an enumeration of each obligation for each agreement is outlined in Note 4, Collaboration Agreements and Revenues. Determining the performance obligations within a collaboration agreement often involves significant judgment and is specific to the facts and circumstances contained in each agreement.

The Company has identified the following material promises under its collaboration agreements: (1) license of FibroGen technology, (2) the performance of co-development services, including manufacturing of clinical supplies and other services during the development period, and (3) manufacture of commercial supply. The evaluation as to whether these promises are distinct, and therefore represent separate performance obligations, is described in more details in Note 4, Collaboration Agreements and Revenues.

For revenue recognition purposes, the Company determines that the term of its collaboration agreements begin on the effective date and ends upon the completion of all performance obligations contained in the agreements. In each agreement, the contract term is defined as the period in which parties to the contract have present and enforceable rights and obligations. The Company believes that the existence of what it considers to be substantive termination penalties on the part of the counterparty create sufficient incentive for the counterparty to avoid exercising its right to terminate the agreement unless in exceptionally rare situations.

The transaction price for each collaboration agreement is determined based on the amount of consideration the Company expects to be entitled for satisfying all performance obligations within the agreement. The Company’s collaboration agreements include payments to the Company of one or more of the following: non-refundable upfront license fees; co-development billings; development, regulatory, and commercial milestone payments; payments from sales of active pharmaceutical ingredient (“API”); payments from sales of bulk drug product and royalties on net sales of licensed products.

Upfront license fees are non-contingent and non-refundable in nature and are included in the transaction price at the point when the license fees become due to the Company. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Co-development billings resulting from the Company’s research and development efforts, which are reimbursable under its collaboration agreements, are considered variable consideration. Determining the reimbursable amount of research and development efforts requires detailed analysis of the terms of the collaboration agreements and the nature of the research and development efforts incurred. Determining the amount of variable consideration from co-development billings requires the Company to make estimates of future research and development efforts, which involves significant judgment. Co-development billings are allocated entirely to the co-development services performance obligation when amounts are related specifically to research and development efforts necessary to satisfy the performance obligation, and such an allocation is consistent with the allocation objective.

Milestone payments are also considered variable consideration, which requires the Company to make estimates of when achievement of a particular milestone becomes probable. Similar to other forms of variable consideration, milestone payments are included in the transaction price when it becomes probable that such inclusion would not result in a significant revenue reversal. Milestone payments are therefore included in the transaction price when achievement of the milestone becomes probable.

For arrangements that include sales-based royalties and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from its collaboration arrangements.

The transaction price is allocated to performance obligations based on their relative standalone selling price (“SSP”), with the exception of co-development billings allocated entirely to co-development services performance obligations. The SSP is determined based on observable prices at which the Company separately sells the products and services. If an SSP is not directly observable, then the Company will estimate the SSP considering marketing conditions, entity-specific factors, and information about the customer or class of customer that is reasonably available. The process for determining SSP involves significant judgment and includes consideration of multiple factors, including assumptions related to the market opportunity and the time needed to commercialize a product candidate pursuant to the relevant license, estimated direct expenses and other costs, which include the rates normally charged by contract research and contract manufacturing organizations for development and manufacturing obligations, and rates that would be charged by qualified outsiders for committee services.

Significant judgment may be required in determining whether a performance obligation is distinct, determining the amount of variable consideration to be included in the transaction price, and estimating the SSP of each performance obligation. An enumeration of the Company’s significant judgments is outlined in Note 4, Collaboration Agreements and Revenues.

For each performance obligation identified within an arrangement, the Company determines the period over which the promised services are transferred and the performance obligation is satisfied. Service revenue is recognized over time based on progress toward complete satisfaction of the performance obligation. For each performance obligation satisfied over time, the Company assesses the proper method to be used for revenue recognition, either an input method to measure progress toward the satisfaction of services or an output method of determining the progress of completion of performance obligation.

Drug product revenue

Drug product revenue includes commercial-grade API or bulk drug product sales to AstraZeneca and Astellas, and is recognized when the Company fulfills the shipment obligations. The drug product revenue is accounted for as variable consideration, estimated at the time of sale using the expected value method. The Company applies significant judgment in estimating the variable consideration, which involves the use of significant assumptions such as the future list price adjustments set by the Japanese Ministry of Health, Labour and Welfare, product mix, and timing of processing of API into bulk drug product.

In 2018, FibroGen and Astellas entered into an amendment to the Japan Agreement that allows Astellas to manufacture roxadustat drug product for commercialization in Japan (the “Japan Amendment”). Under this amendment, FibroGen would continue to manufacture and supply roxadustat API to Astellas for the roxadustat commercial launch in Japan. The drug product revenue represents variable consideration and is estimated based on the quantity of product shipped, actual listed price for roxadustat issued by the Japanese Ministry of Health, Labour and Welfare and possible future changes to the listed price, adjusted for the timing of and estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk drug product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

Under the Europe Agreement with Astellas, Astellas has an option to purchase roxadustat bulk drug product in support of commercial supplies. The drug product revenue amount represents variable consideration and was estimated based on the quantity of product shipped and an estimated price. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price per strength, which is estimated to be realized by Astellas from the end sale of roxadustat in its approved territories.

In 2020, the Company entered into Commercial Supply Agreement under the U.S./RoW Agreement with AstraZeneca to define general forecast, order, supply and payment terms for AstraZeneca to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The drug product revenue amount represents variable consideration and was estimated based on the quantity of product shipped and an estimated price. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price per strength, which is estimated to be realized by AstraZeneca from the end sale of roxadustat in its approved territories.

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and record revenue adjustment, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known. The amount constrained as of December 31, 2020 was $6.0 million related to the drug product shipment to Astellas under the Europe Agreement in the fourth quarter of 2020.

As each of the Company’s collaboration agreements provide for annual true up to the considerations paid for its commercial supplies, the Company will re-evaluate the transaction price in each reporting period and record adjustment to revenue as uncertain events are resolved or other changes in circumstances occur.

Product revenue, net

The Company sells roxadustat in China through a number of pharmaceutical distributors located in China. These pharmaceutical distributors are the Company’s customers. Hospitals order roxadustat through a distributor and the Company ships the product directly to the distributors. The delivery of roxadustat to a distributor represents a single performance obligation. Distributors are responsible for delivering product to end users, primarily hospitals. Distributors bear inventory risk once they receive and accept the product. Product revenue is recognized when control of the promised good is transferred to the customer in an amount that reflects the consideration to which the Company expects to be entitled to in exchange for the product.

The period between the transfer of control of the promised goods and when the Company receives payment is based on a general 60-day payment term. As such, product revenue is not adjusted for the effects of a significant financing component.

Product revenue is recorded at the net sales prices (transaction price) which includes the following estimates of variable consideration:

•

Price adjustment: In December 2019, China’s National Healthcare Security Administration released price guidance for roxadustat under the National Reimbursement Drug List (“NRDL”), effective January 1, 2020. Any channel inventories as of January 1, 2020 that had not been sold to hospitals by distributors, or to patients by hospitals, were eligible for a price adjustment under the price protection. The price adjustment is calculated based on estimated channel inventory levels at January 1, 2020. If price guidance changes in the future, the price adjustment will be calculated in the same manner;

•

Contractual sales rebate: The contractual sales rebate is calculated based on the stated percentage of gross sales by each distributor in the distribution agreement entered between FibroGen and each distributor. The contractual sales rebate is recorded as a reduction to revenue at the point of sale to the distributor;

•

Key account hospital sales rebate: An additional sales rebate is provided to a distributor for product sold to key account hospitals as a percentage of gross sales made by the distributor to eligible hospitals. This additional rebate is recorded as a reduction to revenue at the point of sale to the distributor;

•	Transfer fee discount: The transfer fee discount is offered to a distributor who has its downstream distributors supply to eligible hospitals. This discount is calculated based on a percentage of gross sales made to the downstream distributors, and recorded as a reduction to revenue as incurred;

•	Sales return: Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date; and

•

Non-key account hospital listing award: A one-time fixed-amount award is offered to a distributor who successfully lists the product with an eligible hospital, and who meets certain requirements. The Company considers this particular award to be an upfront payment to a customer within the definitions of ASC 606. The non-key account hospital listing award is capitalized when the distributor meets eligibility requirements, and amortized as reduction to product revenue over future sales orders made by the distributor until exhausted.

The calculation of the above variable consideration is based on gross sales to the distributor, or estimated utilizing best available information from the distributor, maximum known exposures and other available information including estimated channel inventory levels and estimated sales made by the distributor to hospitals, which involve a substantial degree of judgment.

The above rebates and discounts all together are eligible to be applied against the distributor’s future sales order, limited to certain maximums until such rebates and discounts are exhausted. These rebates and discounts are recorded as contract liabilities at the time they become eligible and in the same period that the related revenue is recorded. Due to the distributor’s legal right to offset, at each balance sheet date, the liability for rebates and discounts are presented as reductions of gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The distributor’s legal right of offset is calculated at the individual distributor level.

Research and Development Expenses

Research and development expenses consist of independent research and development costs and the gross amount of costs associated with work performed under collaboration agreements. Research and development costs include employee-related expenses, expenses incurred under agreements with clinical research organizations, other clinical and preclinical costs and allocated direct and indirect overhead costs, such as facilities costs, information technology costs and other overhead. All research and development costs are expensed as incurred.

Clinical Trial Accruals

Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the costs to be recorded based upon validation with the external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.

Selling, General and Administrative Expenses

Selling, general and administrative (“SG&A”) expenses consist primarily of employee-related expenses for executive, operational, finance, legal, compliance and human resource functions. SG&A expenses also include facility-related costs, professional fees, accounting and legal services, other outside services including co-promotional expenses, recruiting fees and expenses associated with obtaining and maintaining patents.

Income Taxes

The Company utilizes the asset and liability method of accounting for income taxes, which requires the recognition of deferred tax assets and liabilities for expected future consequences of temporary differences between the financial reporting and income tax bases of assets and liabilities using enacted tax rates. Management makes estimates, assumptions and judgments to determine the Company’s provision for income taxes and for deferred tax assets and liabilities, and any valuation allowances recorded against the Company’s deferred tax assets. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent the Company believes that recovery is not likely, the Company must establish a valuation allowance.

The calculation of the Company’s current provision for income taxes involves the use of estimates, assumptions and judgments while taking into account current tax laws, interpretation of current tax laws and possible outcomes of future tax audits. The Company has established reserves to address potential exposures related to tax positions that could be challenged by tax authorities. Although the Company believes its estimates, assumptions and judgments to be reasonable, any changes in tax law or its interpretation of tax laws and the resolutions of potential tax audits could significantly impact the amounts provided for income taxes in the Company’s consolidated financial statements.

The calculation of the Company’s deferred tax asset balance involves the use of estimates, assumptions and judgments while taking into account estimates of the amounts and type of future taxable income. Actual future operating results and the underlying amount and type of income could differ materially from the Company’s estimates, assumptions and judgments thereby impacting the Company’s financial position and results of operations.

During 2020, the Company transferred certain intellectual property rights relating to its Chinese business between its wholly owned subsidiaries that are based in different tax jurisdictions. Refer to Note 13, Income Taxes, for more information. The establishment of a deferred tax asset from the intra-entity transfer of intangible assets required the Company to make significant estimates and assumptions to determine the fair value of intellectual property rights transferred, which include but are not limited to, its expectations of discount rate, revenue volume and price. The accuracy of these estimates could be affected by unforeseen events or actual results, and the sustainability of the Company’s future tax benefits is dependent upon the acceptance of these valuation estimates and assumptions by the taxing authorities.

The Company has adopted ASC 740-10, Accounting for Uncertainty in Income Taxes, that prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return, and also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.

The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the Consolidated Statements of Operations.

Stock-Based Compensation

The Company maintains equity incentive plans under which incentive and nonqualified stock options are granted to employees and non-employee consultants. Compensation expense relating to non-employee stock options has not been material for all the periods presented.

The Company measures and recognizes compensation expense for all stock options and restricted stock units (“RSUs”) granted to its employees and directors based on the estimated fair value of the award on the grant date. The Company uses the Black-Scholes valuation model to estimate the fair value of stock option awards. The fair value is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis. The Company believes that the fair value of stock options granted to non-employees is more reliably measured than the fair value of the services received. The determination of the grant date fair value of options using an option pricing model is affected by the Company’s estimated Common Stock fair value and requires management to make a number of assumptions including the expected life of the option, the volatility of the underlying stock, the risk-free interest rate and expected dividends.

Comprehensive Income (Loss)

The Company is required to report all components of comprehensive income (loss), including net loss, in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on investments and foreign currency translation adjustments. Comprehensive gains (losses) have been reflected in the consolidated statements of comprehensive income (loss) for all periods presented.

Recently Issued and Adopted Accounting Guidance

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This guidance requires capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance was effective for annual reporting periods beginning after December 15, 2019, including interim periods. The Company adopted this guidance on January 1, 2020 using the prospective method, and the adoption of this guidance did not have material impact to the Company’s consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This guidance is intended to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. This guidance requires the measurement of financial assets with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. This guidance requires an impairment model, known as the current expected credit loss model, which is based on expected losses rather than incurred losses. Entities are required to carry an allowance for expected credit losses for financial assets, including most debt instruments (except those carried at fair value) and trade receivables. In November 2019, the FASB issued ASU No. 2019-11, Codification Improvements to Topic 326, Financial Instruments-Credit Losses (“ASU 2019-11”), which has the same effective dates and transition requirements as ASU 2016-13. ASU 2016-13 and ASU 2019-11 were effective for annual reporting periods beginning after December 15, 2019 including interim periods. The Company’s investment portfolio primarily consists of U.S. Treasury bills and notes carried at fair value, which is required to follow the impairment model under Topic 326. The Company adopted this guidance on January 1, 2020. Based on the composition of the Company’s trade receivables and investment portfolio, economic conditions and historical credit loss activity, the adoption of this guidance did not have material impact to the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The Company adopted the lease guidance under ASC 842 as of January 1, 2019, using the modified retrospective transition method, through a cumulative-effect adjustment. The adoption of this guidance resulted in a reduction of $8.7 million to the Company’s accumulated deficit and also impacted various balance sheet line items in its consolidated balance sheet as of January 1, 2019 upon adoption. The adoption of this guidance did not have a material impact to the Company’s consolidated statement of operations or consolidated statement of cash flows for the year ended December 31, 2019.

In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The Company adopted this guidance on January 1, 2019 using the modified retrospective approach, with a reduction of $0.6 million to its accumulated other comprehensive loss and an increase of $0.6 million to its accumulated deficit as of January 1, 2019 upon adoption. The adoption of this guidance had no impact to the Company’s consolidated statement of operations or consolidated statement of cash flows for the year ended December 31, 2019.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10). The Company adopted this guidance as of January 1, 2018 using the modified retrospective approach, with an increase of $1.3 million to its accumulated other comprehensive loss and a reduction of $1.3 million to its accumulated deficit as of January 1, 2018 upon adoption. The adoption of this guidance had no impact to the Company’s consolidated statement of cash flows for the year ended December 31, 2018.

Recently Issued Accounting Guidance Not Yet Adopted

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”), which provides companies with optional financial reporting alternatives to reduce the cost and complexity associated with the accounting for contracts and hedging relationships affected by reference rate reform. This guidance is effective as of March 12, 2020 through December 31, 2022. Subsequently in January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope, which clarifies ASU 2020-04 and provides certain optional expedients that allow derivative instruments impacted by changes in the interest rate used for margining, discounting or contract price alignment to qualify for certain optional relief. ASU 2021-01 is effective in the same timeframe as ASU 2020-04. The relief offered by this guidance, if adopted, is available to companies for the period March 12, 2020 through December 31, 2022. The Company has certain lease arrangements that are linked to LIBOR. The Company is in the process of evaluating options for transitioning away from LIBOR and expects to complete by the time LIBOR is phased out. The Company did not elect to apply any of the expedients or exceptions as of and for the year ended December 31, 2020 and is currently evaluating the impact on its consolidated financial statements and related disclosures upon adoption of this guidance.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This guidance simplifies the accounting for income taxes by clarifying and amending existing guidance related to the recognition of franchise tax, the evaluation of a step up in the tax basis of goodwill, and the effects of enacted changes in tax laws or rates in the effective tax rate computation, among other clarifications. This guidance is effective for annual reporting periods beginning after December 15, 2020 including interim periods, with early adoption permitted. The Company does not plan to early adopt this guidance and does not anticipate a material impact to its consolidated financial statements upon adoption of this guidance.

Acquisition and Variable Interest Entity

12 Months Ended

Dec. 31, 2020

Acquisition And Variable Interest Entity [Abstract]

Acquisition and Variable Interest Entity

3.	Acquisition and Variable Interest Entity

On July 8, 2020, FibroGen Cayman, FibroGen Beijing, and FibroGen International (Hong Kong) Limited (collectively, “FibroGen China”) and AstraZeneca entered into an amendment, effective July 1, 2020, to the collaboration agreement for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in China (“China Agreement”), relating to the development and commercialization of roxadustat in China (the “China Amendment”).

The China Amendment provides for the establishment of a jointly owned entity that will perform roxadustat distribution, as well as conduct sales and marketing through AstraZeneca. To prepare for the establishment of this jointly owned entity, in July 2020, FibroGen Beijing acquired 100% of the outstanding shares of Beijing Kangda Yongfu Pharmaceutical Co., LTD (“Kangda”) in exchange for cash consideration of CNY15.0 million (approximately $2.1 million). The purpose of the acquisition was to acquire a distribution license owned by Kangda for commercializing and distributing roxadustat in China. FibroGen Beijing continues to hold all of the regulatory licenses issued by China regulatory authorities and continues to be primarily responsible for regulatory, clinical, manufacturing, medical affairs and pharmacovigilance. The transaction costs related to the execution of the acquisition, primarily legal expenses, totaled CNY5.0 million and were shared equally with AstraZeneca. Therefore, the acquisition costs for FibroGen Beijing were CNY2.5 million (approximately $0.4 million).

Under the ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, the Company determined that the all of the value of Kangda was attributable to the acquired license, and therefore the transaction was accounted for as an asset acquisition. The Company allocated the entire purchase price of $2.5 million to the acquired license that was recorded as an intangible asset, to be amortized over the duration of expected sales of roxadustat. There was no excess consideration over the estimated fair value. Through September 15, 2020, Kangda was consolidated as a wholly owned subsidiary of the Company. The amortization of the license was immaterial during the short period of time before Kangda was deconsolidated upon the establishment of the jointly owned entity described below.

On September 15, 2020, FibroGen Beijing and AstraZeneca entered into an equity transfer agreement and shareholders agreement, under which FibroGen Beijing sold 48.9% of the outstanding shares of Kangda to AstraZeneca in exchange for cash consideration of CNY7.3 million (approximately $1.0 million). Concurrently with the equity transfer, the two parties renamed Kangda to Beijing Falikang Pharmaceutical Co. Ltd. (“Falikang”). Following the sale, FibroGen Beijing owns 51.1% of the outstanding shares of Falikang. The gain (loss) resulting from the equity transfer was immaterial.

In addition, based on the shareholders’ resolutions of Falikang, in December 2020, FibroGen Beijing made cash contribution of CNY8.9 million (approximately $1.4 million) to Falikang, representing 51.1% of Falikang’s registered capital of CNY17.5 million. AstraZeneca completed its cash contribution of 48.9% of Falikang’s registered capital in December 2020 as well.

Pursuant to the guidance under ASC 810, the Company concluded that Falikang qualifies as a VIE. As Falikang is a distribution entity for roxadustat and AstraZeneca is the final decision maker for all the roxadustat commercialization activities, the Company lacks the power criterion while AstraZeneca meets both the power and economic criteria under ASC 810, to direct the activities of Falikang that most significantly impact its performance. Therefore, the Company is not the primary beneficiary of this VIE. As a result, the Company accounted for its investment in Falikang under the equity method, and Falikang is not consolidated into the Company’s consolidated financial statements. Accordingly, The Company recorded its total investments in Falikang of CNY19.2 million (approximately $2.8 million), which is the total of the 51.1% of Falikang’s equity and the acquisition costs, as an investment in unconsolidated subsidiary in other assets in the consolidated balance sheet. In addition, the Company recognized its proportionate share of the reported profits or losses of Falikang, beginning September 15, 2020, as other income (loss) in the consolidated statement of operations, and as an adjustment to its investment in unconsolidated subsidiary in the consolidated balance sheet. Falikang has not incurred material profit or loss to date. The Company may be required to provide shareholder loans to Falikang to meet necessary financial obligations as part of its operations. To date, these loans have been immaterial.

The Company’s equity method investment in Falikang was as follows for the year ended December 31, 2020 (in thousands):

Entity

Ownership Percentage

Balance at

December 31, 2019

Additions

Share of Net Loss

Currency

Translation

Balance at

December 31, 2020

Falikang

51.1

—

2,825

(202

)

105

2,728

Falikang is considered as a related party to the Company. See Note 14, Related Party Transactions, for related disclosures.

On an ongoing basis, the Company will re-evaluate the VIE assessment based on changes in facts and circumstances, including but not limited to, the shareholder loans received by Falikang and the execution of any future significant agreements between Falikang and its shareholders and/or other third parties.

The Company will assess the impairment of its equity method investment whenever events or changes in circumstances indicate that a decrease in value of the investment has occurred that is other than temporary.

Collaboration Agreements and Revenues

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration Agreements and Revenues

4.	Collaboration Agreements and Revenues

Astellas Agreements

Japan Agreement

In June 2005, the Company entered into a collaboration agreement with Astellas for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in Japan (“Japan Agreement”). Under this agreement, Astellas paid license fees and other consideration totaling $40.1 million (such amounts were fully received as of February 2009). Under the Japan Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $132.5 million in potential milestone payments, comprised of (i) up to $22.5 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of July 2016), (ii) up to $95.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $15.0 million in milestone payments upon the achievement of specified commercial sales milestone. The Japan Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range of the list price published by the Japanese Ministry of Health, Labour and Welfare, adjusted for certain elements, after commercial launch. The aggregate amount of the considerations received under the Japan Agreement, through December 31, 2020 totals $105.1 million, excluding drug product revenue that is discussed separately below.

During the fourth quarter of 2020, the Japanese Ministry of Health, Labour and Welfare approved EVRENZO® (roxadustat) for the treatment of anemia of CKD in adult patients not on dialysis. This approval triggered a $15.0 million milestone payable to the Company by Astellas under the Japan Agreement. Accordingly, the consideration of $15.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Japan Agreement in the fourth quarter of 2020, substantially all of which was recognized as revenue during the year ended December 31, 2020 from performance obligations satisfied or partially satisfied.

In September 2019, the Japanese Ministry of Health, Labour and Welfare approved EVRENZO® (generic name: roxadustat; tradename EVRENZO® in Japan) for the treatment of anemia associated with CKD in dialysis patients. This approval triggered a $12.5 million milestone payable to the Company by Astellas under the Japan Agreement. Accordingly, the consideration of $12.5 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Japan Agreement in the third quarter of 2019, substantially all of which was recognized as revenue during the year ended December 31, 2019 from performance obligations satisfied or partially satisfied.

During the second quarter of 2018, Astellas reported positive results from the final phase 3 CKD-dialysis trial of roxadustat in Japan, indicating that Astellas was ready to make an NDA submission for the treatment of anemia with roxadustat in CKD-dialysis patients in 2018. The Company evaluated the regulatory milestone payment associated with NDA submission in Japan based on variable consideration requirements under the current revenue standards and concluded that this milestone became probable of being achieved in the second quarter of 2018. Accordingly, the consideration of $15.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Japan Agreement in the second quarter of 2018, substantially all of which was recognized as revenue during the year ended December 31, 2018 from performance obligations satisfied or partially satisfied.

In 2018, FibroGen and Astellas entered into an amendment to the Japan Agreement that allows Astellas to manufacture roxadustat drug product for commercialization in Japan (the “Japan Amendment”). Under this amendment, FibroGen would continue to manufacture and supply roxadustat API to Astellas for the roxadustat commercial launch in Japan. The commercial terms of the Japan Agreement relating to the transfer price for roxadustat for commercial use remain substantially the same, reflecting an adjustment for the manufacture of drug product by Astellas rather than FibroGen. The Company fulfilled shipment obligations under the term of the Japan Amendment in the second quarter of 2020 and in 2018. The related drug product revenue, as described in details under Drug Product Revenue section below, were $4.3 million, $(36.3) million and $64.8 million in the years ended December 31, 2020, 2019 and 2018, respectively.

Europe Agreement

In April 2006, the Company entered into a separate collaboration agreement with Astellas for the development and commercialization of roxadustat for the treatment of anemia in Europe, the Middle East, the Commonwealth of Independent States and South Africa (“Europe Agreement”). Under the terms of the Europe Agreement, Astellas paid license fees and other upfront consideration totaling $320.0 million (such amounts were fully received as of February 2009). The Europe Agreement also provides for additional development and regulatory approval milestone payments up to $425.0 million, comprised of (i) up to $90.0 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of 2012), (ii) up to $335.0 million in milestone payments upon achievement of specified regulatory milestone events. Under the Europe Agreement, Astellas committed to fund 50% of joint development costs for Europe and North America, and all territory-specific costs. The Europe Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range. The aggregate amount of the considerations received under the Europe Agreement through December 31, 2020 totals $540.0 million, excluding drug product revenue that is discussed separately below.

During the second quarter of 2019, the Company received positive topline results from analyses of pooled major adverse cardiovascular event (“MACE”) and MACE+ data from its Phase 3 trials evaluating roxadustat as a treatment for dialysis and non-dialysis CKD patients, enabling Astellas to prepare for an MAA submission to the EMA in the second quarter of 2020, following the Company’s NDA submission to the FDA that was accepted for review in February 2020. The Company evaluated the two regulatory milestone payments associated with the planned MAA submission and concluded that these milestones became probable of being achieved in the second quarter of 2019. Accordingly, the total consideration of $130.0 million associated with these milestones was included in the transaction price and allocated to performance obligations under the Europe Agreement in the second quarter of 2019, of which $128.8 million was recognized as revenue during the year ended December 31, 2019 and $0.8 million was recognized as revenue during the year ended December 31, 2020, from performance obligations satisfied or partially satisfied. According to the Europe Agreement, these milestone payments are billable to Astellas upon the submission of an MAA, therefore this $130.0 million was an unbilled contract asset as of December 31, 2019, and billed to Astellas upon the submission of an MAA in the second quarter of 2020 with the total $130.0 million received during the same quarter.

In the fourth quarter of 2018, the Company was engaged in the final stages of review with its partners over the proposed development of roxadustat for the treatment of chemotherapy-induced anemia (“CIA”). AstraZeneca and Astellas approved the program in December 2018 and January 2019, respectively. Costs associated with the development of this indication are expected to be shared 50-50 between the Company’s two partners. For revenue recognition purposes, the Company concluded that this new indication represents a modification to the Europe agreements and will be accounted for separately, meaning the development costs associated with the new indications are distinct from the original development costs. The development service period for roxadustat for the treatment of CIA under the Europe Agreement is estimated to continue through the second quarter of 2024 to allow for development of this indication.

Under the Europe Agreement, Astellas has an option to purchase roxadustat bulk drug product in support of commercial supplies. The Company fulfilled a shipment obligation under the term of the Europe Amendment in the fourth quarter of 2020, as described in details under Drug Product Revenue section below.

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

Effective July 30, 2013, the Company entered into a collaboration agreement with AstraZeneca for the development and commercialization of roxadustat for the treatment of anemia in the U.S. and all other countries in the world, other than China, not previously licensed under the Astellas Europe and Astellas Japan Agreements (“U.S./RoW Agreement”). It also excludes China, which is covered by a separate agreement with AstraZeneca described below. Under the terms of the U.S./RoW Agreement, AstraZeneca paid upfront, non-contingent, non-refundable and time-based payments totaling $374.0 million (such amounts were fully received as of June 2016). Under the U.S./RoW Agreement, the Company is also eligible to receive from AstraZeneca an aggregate of approximately $875.0 million in potential milestone payments, comprised of (i) up to $65.0 million in milestone payments upon achievement of specified clinical and development milestone events, (ii) up to $325.0 million in milestone payments upon achievement of specified regulatory milestone events, (iii) up to $160.0 million in milestone payments related to activity by potential competitors and (iv) up to approximately $325.0 million in milestone payments upon the achievement of specified commercial sales events. The aggregate amount of the considerations received under the U.S./RoW Agreement through December 31, 2020 totals $439.0 million, excluding drug product revenue that is discussed separately below.

Under the U.S./RoW Agreement, the Company and AstraZeneca will share equally in the development costs of roxadustat not already paid for by Astellas, up to a total of $233.0 million (i.e. the Company’s share of development costs is $116.5 million, which was reached in 2015). Development costs incurred by FibroGen during the development period in excess of the $233.0 million (aggregated spend) are fully reimbursed by AstraZeneca. AstraZeneca will pay the Company tiered royalty payments on AstraZeneca’s future net sales (as defined in the agreement) of roxadustat in the low 20% range. In addition, the Company will receive a transfer price for shipment of commercial product based on a percentage of AstraZeneca’s net sales (as defined in the agreement) in the low- to mid-single digit range.

As mentioned above, during the second quarter of 2019, the Company received positive topline results from analyses of pooled MACE and MACE+ data from its Phase 3 trials for roxadustat, enabling the Company’s NDA submission to the FDA. The Company evaluated the regulatory milestone payment associated with this planned NDA submission and concluded that this milestone became probable of being achieved in the second quarter of 2019. Accordingly, the consideration of $50.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the combined arrangement in the second quarter of 2019, of which $42.4 million was recognized as revenue during the year ended December 31, 2019 and $0.6 million was recognized as revenue during the year ended December 31, 2020, from performance obligations satisfied or partially satisfied. The Company submitted such NDA in December 2019, which was accepted by FDA in February 2020. According to the U.S/RoW Agreement, this milestone payment is billable to AstraZeneca when the NDA is accepted by the FDA, therefore this $50.0 million was an unbilled contract asset as of December 31, 2019, and was billed during the first quarter of 2020, the payment of which was fully received in April 2020.

As mentioned above, AstraZeneca and Astellas approved the development of roxadustat for the treatment of CIA in December 2018 and January 2019, respectively. Costs associated with the development of this indication are expected to be shared 50/50 between AstraZeneca and Astellas. In addition, in December 2018, anemia of chronic inflammation and multiple myeloma was approved for development by AstraZeneca and is expected to be fully funded by them. For revenue recognition purposes, the Company concluded that the addition of these new indications represents a modification to the collaboration agreements and will be accounted for separately, meaning the development costs associated with the new indications are distinct from the original development costs. The development service period for roxadustat for the treatment of CIA, anemia of chronic inflammation and multiple myeloma under the AstraZeneca agreements is estimated to continue through the end of 2024, to allow for development of these additional indications.

In 2020, the Company entered into Commercial Supply Agreement under the U.S./RoW Agreement with AstraZeneca to define general forecast, order, supply and payment terms for AstraZeneca to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The Company shipped bulk drug product to AstraZeneca as pre-commercial supply for process validation purposes during the year ended December 31, 2020 and recognized related drug product revenue of $4.6 million, as described in details under Drug Product Revenue section below.

China Agreement

Effective July 30, 2013, the Company (through its subsidiaries affiliated with China) entered into a collaboration agreement with AstraZeneca for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in China (“China Agreement”). Under the terms of the China Agreement, AstraZeneca agreed to pay upfront consideration totaling $28.2 million (such amounts were fully received in 2014). Under the China Agreement, the Company is also eligible to receive from AstraZeneca an aggregate of approximately $348.5 million in potential milestone payments, comprised of (i) up to $15.0 million in milestone payments upon achievement of specified clinical and development milestone events, (ii) up to $146.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $187.5 million in milestone payments upon the achievement of specified commercial sales and other events. The China Agreement is structured as a 50/50 profit or loss share (as defined), which was amended under the China Amendment discussed below in the third quarter of 2020, and provides for joint development costs (including capital and equipment costs for construction of the manufacturing plant in China), to be shared equally during the development. The aggregate amount of the considerations received under the China Agreement through December 31, 2020 totals $77.2 million.

In December 2019, roxadustat has been included on the updated NRDL released by China’s National Healthcare Security Administration for the treatment of anemia in CKD, covering patients who are non-dialysis dependent as well as those who are dialysis-dependent. The inclusion on the NRDL triggered a total of $22.0 million milestones payable to the Company by AstraZeneca. Accordingly, the total consideration of $22.0 million associated with these milestones was included in the transaction price and allocated to performance obligations under the combined arrangement, of which $18.7 million was recognized as revenue during the year ended December 31, 2019. The Company continued to recognize related revenue during the year ended December 31, 2020, from performance obligations satisfied or partially satisfied, and the amount was not material. This milestone payment was received during the first quarter of 2020.

On December 17, 2018, FibroGen Beijing, received marketing authorization from the NMPA for roxadustat, a first-in-class HIF prolyl hydroxylase inhibitor, for the treatment of anemia caused by CKD in patients on dialysis. This approval triggered a $6.0 million milestone payable to the Company by AstraZeneca. On December 29, 2018, FibroGen Beijing received First Manufacturing Approval for a Product in the Field in the Territory, which allows production for Phase 4 clinical studies, patients’ early experience programs, donation programs, as well as to supply products for testing and assessments required prior to launch. This approval triggered a $6.0 million milestone payable to the Company by AstraZeneca. Approximately $9.9 million of the total $12.0 million milestone payables was recognized as revenue during the year ended December 31, 2018. The Company continued to recognize related revenues during the years ended December 31, 2019 and 2020, from performance obligations satisfied or partially satisfied, and the amounts were not material.

China Amendment

On July 8, 2020, FibroGen China and AstraZeneca (together with FibroGen China, the “Parties”) entered into the China Amendment, effective July 1, 2020, relating to the development and commercialization of roxadustat in China. While the responsibilities of the Parties under the China Agreement remain largely the same, certain changes were made.

Under the China Amendment, in September 2020, FibroGen Beijing and AstraZeneca completed the establishment of a jointly owned entity, Falikang, which will perform roxadustat distribution, as well as conduct sales and marketing through AstraZeneca. See Note 3, Acquisition and Variable Interest Entity, for details.

In accordance with the China Amendment, the Company is currently in the interim period. Under the China Amendment, the interim period is defined as the period from April 1, 2020 to the time when Falikang is fully operational, which commenced in January 2021. During the interim period, FibroGen continues to sell product directly to the distributors, who remain as the Company’s customers. Under the China Amendment, the calculation for profit or loss share has changed related to sales of roxadustat in China for the period from April 1, 2020 onwards. With effect from April 1, 2020, the Parties have changed the method under which commercial expenses incurred by AstraZeneca are calculated and billed. AstraZeneca’s co-promotion expenses for their sales and marketing efforts are now subject to a cap of a percentage of net sales. Once AstraZeneca has been fully reimbursed for their sales and marketing costs under the cap, AstraZeneca will bill the co-promotion expenses based on actual costs on a prospective basis. In addition, the China Amendment has allowed for a higher cost of manufacturing incurred by FibroGen Beijing to be included in the profit or loss share calculation, subject to an annual cap, among other changes.

Once Falikang is fully operational, substantially all direct product sales will be made by Falikang while the Company continues to sell product directly in few provinces in China. AstraZeneca will bill the co-promotion expenses to Falikang and to FibroGen Beijing, respectively, for its services provided to the respective entity. In addition, FibroGen Beijing will sell commercial product to Falikang based on an agreed upon transfer price. Development costs will continue to be shared 50/50 between the Parties.

As a result, the interim period primarily includes the following activities:

•

Co-promotion expenses: The China Amendment revised the payment arrangements and calculation of the historical unpaid co-promotion expenses to AstraZeneca for its sales and marketing efforts associated with the commercial sales for roxadustat in China since the product launch. Under the previous China Agreement, payment of these historical co-promotion expenses was subject to certain profitability and cash flow thresholds. No amount of the historical co-promotion costs had been paid prior to the China Amendment as these thresholds had not yet been met. Under the China Amendment, a portion of the historical unpaid co-promotion expenses was adjusted to reduce the amount owed by FibroGen Beijing and the current period co-promotion expenses are capped at a percentage of net roxadustat sales in China. As a result, in the third quarter of 2020, the Company reversed approximately $84.4 million of previously accrued co-promotion expenses payable, which was recorded as a reduction to selling, general and administrative expenses, where these expenses were initially recorded during the periods from the initiation of commercial activities in the first quarter of 2019 to the second quarter of 2020. The co-promotion expenses for the year ended December 31, 2020, capped at a percentage of net roxadustat sales in China, were $27.2 million, included in the selling, general and administrative expenses. After this adjustment, as of December 31, 2020, $16.9 million and $11.5 million of the recalculated accrued co-promotion expenses were recorded in accounts payable and accrued liabilities, respectively, as they were anticipated to be paid within the next 12 months; and $27.4 million of the recalculated accrued co-promotion expenses adjusted under the China Amendment remained in the long-term liabilities, as it is not anticipated to be paid within the next 12 months.

•

Profit share: Profit/loss share between FibroGen Beijing and AstraZeneca is based on a calculation of the current period net roxadustat sales in China and deductible expenses pursuant to the China Agreement. Based on the calculation revised under the China Amendment, profit was achieved during the third and fourth quarter of 2020. As a result, the Company recorded a profit share liability of $7.0 million to AstraZeneca as of December 31, 2020 in the accrued and other current liabilities, which correspondingly reduced the deferred revenue related to the performance obligation in accordance with the China Agreement.

Accounting for the Astellas Agreements

For each of the Astellas agreements, the Company has evaluated the promised services within the respective arrangements and has identified performance obligations representing those services and bundles of services that are distinct.

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual services. There are no right-of-return provisions for the delivered items in the Astellas agreements.

As of December 31, 2020, the transaction price for the Japan Agreement, excluding manufacturing services that is discussed separately below, included $40.1 million of non-contingent upfront payments, $65.0 million of variable consideration related to payments for milestones considered probable of being achieved, and $11.7 million of variable consideration related to co-development billings. The transaction price for the Europe Agreement, excluding manufacturing services that is discussed separately below, included $320.0 million of non-contingent upfront payments, $220.0 million of variable consideration related to payments for milestones considered probable of being achieved, and $225.9 million of variable consideration related to co-development billings.

For revenue recognition purposes, the Company determined that the term of each collaboration agreement with Astellas begins on the effective date and ends upon the completion of all performance obligations contained in the agreement. The contract term is defined as the period in which parties to the contract have present and enforceable rights and obligations. The Company believes that the requirement to continue funding development for a substantive period of time and loss of product rights, along with non-refundable upfront payments already remitted by Astellas, create significant disincentive for Astellas to exercise its right to terminate the agreements.

For the Astellas agreements, the Company allocated the transaction price to the various performance obligations based on the relative SSP of each performance obligation, with the exception of co-development billings allocated entirely to co-development services performance obligations.

For the technology license under the Japan Agreement and the Europe Agreement, SSP was determined primarily by using the discounted cash flow (“DCF”) method, which aggregates the present value of future cash flows to determine the valuation as of the effective date of each of the agreements. The DCF method involves the following key steps: 1) the determination of cash flow forecasts and 2) the selection of a range of comparative risk-adjusted discount rates to apply against the cash flow forecasts. The discount rates selected were based on expectations of the total rate of return, the rate at which capital would be attracted to the Company and the level of risk inherent within the Company. The discounts applied in the DCF analysis ranged from 17.5% to 20.0%. The Company’s cash flow forecasts were derived from probability-adjusted revenue and expense projections by territory. Such projections included consideration of taxes and cash flow adjustments. The probability adjustments were made after considering the likelihood of technical success at various stages of clinical trials and regulatory approval phases. SSP also considered certain future royalty payments associated with commercial performance of the Company’s compounds, transfer prices and expected gross margins.

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

License to the Company’s technology existing at the effective date of the agreements. For both of the Astellas agreements, the license was delivered at the beginning of the agreement term. In both cases, the Company concluded at the time of the agreement that its collaboration partner, Astellas, would have the knowledge and capabilities to fully exploit the licenses without the Company’s further involvement. However, the Japan Agreement has contractual limitations that might affect Astellas’ ability to fully exploit the license and therefore, potentially, the conclusion as to whether the license is capable of being distinct. In the Japan Agreement, Astellas does not have the right to manufacture commercial supplies of the drug. In order to determine whether this characteristic of the agreement should lead to a conclusion that the license was not distinct in the context of the agreement, the Company considered the ability of Astellas to benefit from the license together with other resources readily available to Astellas. Finally, the Company considered the fact that at the time of delivery of the license, the development services were beyond the preclinical development phase and any remaining development work in either agreement would not be expected to result in any significant modification or customization to the licensed technology. As such, the development services are separately identifiable from the licensed technology, indicating that the license is a distinct performance obligation.

Manufacturing rights. In the case of the Japan Agreement, the Company retained manufacturing rights largely because of the way the parties chose for FibroGen to be compensated under the agreement. At the time the agreement was signed, the Company believed that it was more advantageous upon commercialization to have a transfer price revenue model in place as opposed to a traditional sales-based model. The manufacturing process does not require specialized knowledge or expertise uniquely held by FibroGen, and notwithstanding contractual restrictions, Astellas could employ manufacturing services from readily available third parties in order to benefit from the license. Therefore, along with the foregoing paragraph, the Company determined that the license in Japan is a distinct performance obligation despite the retention of manufacturing rights by the Company.

In summary, the Company concludes that item (1) represents a performance obligation. The portion of the transaction price allocated to this performance obligation based on a relative SSP basis is recognized as revenue in its entirety at the point in time the license transfers to Astellas.

(2)

Co-development services (Europe Agreement). This promise relates to co-development services that were reasonably expected to be performed by the Company at the time the collaboration agreement was signed and is considered distinct. Co-development billings are allocated entirely to the co-development services performance obligation as amounts are related specifically to research and development efforts necessary to satisfy the performance obligation, and such an allocation is consistent with the allocation objective. Revenue is recognized over time based on progress toward complete satisfaction of the performance obligation. The Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours and out-of-pocket expenses incurred relative to total expected costs to be incurred. The measure of progress is updated each reporting period. Co-development services are expected to continue over the development period that is currently estimated to continue through the end of 2021. In addition, the Company concluded that the new indication related to CIA approved in January 2019 represents a modification to the Europe agreements at that time and will be accounted for separately, for which the development service period is estimated to continue through the second quarter of 2024. There was no provision for co-development services in the Japan Agreement.

(3)	License to the Company’s technology developed during the term of the agreement and development (referred to as “when and if available”) and information sharing services. These promises are generally satisfied throughout the term of the agreements.

(4)	Manufacturing of clinical supplies of products. This promise is satisfied as supplies for clinical product are delivered for use in the Company’s clinical trial programs during the development period, or pre-commercialization period.

(5)	Committee service. This promise is satisfied throughout the course of the agreements as meetings are attended.

Items (2)-(5) are bundled into a single performance obligation that is distinct given the fact that all are highly interrelated during the development period (pre-commercial phase of development) such that satisfying them independently is not practicable. Revenue is recognized over time based on progress toward complete satisfaction of the performance obligation. The Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred. The measure of progress is updated each reporting period.

(6)

Manufacturing commercial supplies of products. This promised service is distinct as services are not interrelated with any of the other performance obligations. Payments received for commercial supplies of products represent sales-based payments related predominately to the license of intellectual property under both Astellas agreements. Revenue is recognized as supplies are shipped for commercial use during the commercialization period.

Under the Japan Amendment the drug product revenue represents variable consideration and is estimated based on the quantity of product shipped, actual listed price for roxadustat issued by the Japanese Ministry of Health, Labour and Welfare and possible future changes to the listed price, adjusted for estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk drug product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

Under the Europe Agreement, the drug product revenue amount represents variable consideration and is estimated based on the quantity of product shipped and an estimated price. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price per strength, which is estimated to be realized by Astellas from the end sale of roxadustat in its approved territories.

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and records an adjustment to revenue, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known.

As each of the agreements provides for annual true up to the considerations paid for its commercial supplies, the Company will re-evaluate the transaction price in each reporting period and record adjustment to revenue as uncertain events are resolved or other changes in circumstances occur.

Accounting for the AstraZeneca Agreements

The Company evaluated whether the U.S./RoW Agreement and the China Agreement should be accounted for as a single or separate arrangements and concluded that the agreements should be accounted for as a single arrangement with the presumption that two or more agreements executed with a single customer at or around the same time should be presumed to be a single arrangement. The key points the Company considered in reaching this conclusion are as follows:

1.	While the two agreements were largely negotiated separately, those negotiations proceeded concurrently, and were intended to be completed contemporaneously, presuming AstraZeneca decided to proceed with licenses in all regions available.

Throughout negotiations for both agreements, the Company and the counterparties understood and considered the possibility that one arrangement may be executed without the execution of the other arrangement. However, the preference for the Company and the counterparties during the negotiations was to execute both arrangements concurrently.

The two agreements were executed as separate agreements because different development, regulatory and commercial approaches required certain terms of the agreements to be structured differently, rather than because the Company or the counterparties considered the agreements to be fundamentally separate negotiations.

Accordingly, as the agreements are being accounted for as a single arrangement, upfront and other non-contingent consideration received and to be received has been and will be pooled together and allocated to each of the performance obligations in both the U.S./RoW Agreement and the China Agreement based on their relative SSPs.

For each of the AstraZeneca agreements, the Company has evaluated the promised services within the respective arrangements and has identified performance obligations representing those services and bundled services that are distinct.

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual promised services. There are no right-of-return provisions for the delivered items in the AstraZeneca agreements.

As of December 31, 2020, the transaction price for the U.S./RoW Agreement and the China Agreement, excluding manufacturing services that is discussed separately below, included $402.2 million of non-contingent upfront payments, $114.0 million of variable consideration related to payments for milestones considered probable of being achieved, $564.9 million of variable consideration related to co-development billings, offset by $7.0 million of variable consideration related to profit share under the China Amendment.

For the AstraZeneca agreements, the Company allocated the transaction price to the various performance obligations based on the relative SSP of each performance obligation, with the exception of co-development billings and commercial sale of product. Co-development billings under the U.S./RoW Agreement were allocated entirely to the U.S./RoW co-development services performance obligation, and co-development billings under the China Agreement were allocated entirely to the combined performance obligation under the China Agreement. Commercial sale of product under the U.S./ROW Agreement is entirely allocated to the manufacturing commercial supply of products performance obligation, and commercial sale of product under the China Agreement is allocated entirely to the combined China performance obligation.

For revenue recognition purposes, the Company determined that the term of its collaboration agreements with AstraZeneca begin on the effective date and ends upon the completion of all performance obligations contained in the agreements. The contract term is defined as the period in which parties to the contract have present and enforceable rights and obligations. The Company believes that the requirement to continue funding development for a substantive period of time and the loss of product rights, along with non-refundable upfront payments already remitted by AstraZeneca, represent substantive termination penalties that create significant disincentive for AstraZeneca to exercise its right to terminate the agreement.

For the technology license under the AstraZeneca U.S./RoW Agreement, SSP was determined based on a two-step process. The first step involved determining an implied royalty rate that would result in the net present value of future cash flows to equal to zero (i.e. where the implied royalty rate on the transaction would equal the target return for the investment). This results in an upper bound estimation of the magnitude of royalties that a hypothetical acquirer would reasonably pay for the forecasted cash flow stream. The Company’s cash flow forecasts were derived from probability-adjusted revenue and expense projections. Such projections included consideration of taxes and cash flow adjustments. The probability adjustments were made after considering the likelihood of technical success at various stages of clinical trials and regulatory approval phases. The second step involved applying the implied royalty rate, which was determined to be 40%, against the probability-adjusted projected net revenues by territory and determining the value of the license as the net present value of future cash flows after adjusting for taxes. The discount rate utilized was 17.5%.

U.S./RoW Agreement:

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

License to the Company’s technology existing at the effective date of the agreements. For the U.S./RoW Agreement, the license was delivered at the beginning of the agreement term. The Company concluded that AstraZeneca has the knowledge and capabilities to fully exploit the license under the U.S./RoW Agreement without the Company’s further involvement. Finally, the Company considered the fact that at the time of delivery of the license, the development services were beyond the preclinical development phase and any remaining development work would not be expected to result in any significant modification or customization to the licensed technology. As such, the development services are separately identifiable from the licensed technology, indicating that the license is a distinct performance obligation. Therefore, the Company has concluded that the license is distinct and represents a performance obligation. The portion of the transaction price allocated to this performance obligation based on a relative SSP basis is recognized as revenue in its entirety at the point in time the license transfers to AstraZeneca.

(2)

Co-development services. This promise relates to co-development services that were reasonably expected to be performed by the Company at the time the collaboration agreement was signed and is distinct. Co-development billings are allocated entirely to the co-development services performance obligation as amounts are related specifically to research and development efforts necessary to satisfy the performance obligation, and such an allocation is consistent with the allocation objective. Revenue is recognized over time based on progress toward complete satisfaction of the performance obligation. The Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred. Co-development services are expected to continue over the development period that is currently estimated to continue through the end of the first quarter of 2021. In addition, the Company concluded that the addition of the new indications related to CIA, anemia of chronic inflammation and multiple myeloma approved during the fourth quarter of 2018 represents a modification to the collaboration agreements and will be accounted for separately, for which the joint development service period is estimated to continue through the end of 2024.

(3)	Manufacturing of clinical supplies of products. This promise is satisfied as supplies for clinical product are delivered for use in the Company’s clinical trial programs during the development period, or pre-commercialization period.

(4)	Information sharing and committee service. These promises are satisfied throughout the course of the agreement as services are provided.

Items (2)-(4) are bundled into a single performance obligation that is distinct given the fact that all are highly interrelated during the development period (pre-commercial phase of development) such that delivering them independently is not practicable. Revenue is recognized over time based on progress toward complete satisfaction of the performance obligation. The Company uses an input method to measure progress toward the satisfaction of the performance obligation, which is based on costs of labor hours or full time equivalents and out-of-pocket expenses incurred relative to total expected costs to be incurred. The measure of progress is updated each reporting period.

(5)

Manufacturing commercial supplies of products. This promise is distinct as services are not interrelated with any of the other performance obligations. Revenue is recognized as supplies are shipped for commercial use during the commercialization period. The drug product revenue amount represents variable consideration and is estimated based on the quantity of product shipped and an estimated price for each individual purchase order. The estimated price is based on the contractual transfer price percentage applied on the estimated weighted average net sales price, which is estimated to be realized by AstraZeneca from the end sale of roxadustat in its approved territories.

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and records an adjustment to revenue, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known.

As the agreement provides for an annual true up to the considerations paid for its commercial supplies, the Company will re-evaluate the transaction price in each reporting period and record an adjustment to revenue as uncertain events are resolved or other changes in circumstances occur.

China Agreement:

The promised services that were analyzed are consistent with the U.S./RoW Agreement, except for license to the Company’s technology existing at the effective date of the agreement, described as follows:

•

License to the Company’s technology existing at the effective date of the agreement. The license was delivered at the beginning of the agreement term. However, the China Agreement with AstraZeneca has contractual limitations that might affect AstraZeneca’s ability to fully exploit the license and therefore, potentially, the conclusion as to whether the license is distinct in the context of the agreement. In the China Agreement, AstraZeneca does not have the right to manufacture commercial supplies of the drug. In order to determine whether this characteristic of the arrangement should lead to a conclusion that the license was not distinct in the context of the agreement, the Company considered the ability of AstraZeneca to benefit from the license on its own or together with other resources readily available to AstraZeneca.

For the China Agreement, the Company retained manufacturing rights as an essential part of a strategy to pursue domestic regulatory pathway for product approval which requires the regulatory licensure of the manufacturing facility in order to commence commercial shipment. The prospects for the collaboration as a whole would have been substantially different had manufacturing rights been provided to AstraZeneca. We hold the rights to manufacture commercial drug product in China. Therefore, AstraZeneca cannot benefit from the license on its own or together with other readily available resources. Accordingly, all the promises identified, including the license, co-development services and manufacturing of commercial supplies,, under the China Agreement have been bundled into a single performance obligation and amounts of the transaction price allocable to this performance obligation are deferred until control of the manufactured commercial drug product has begun to transfer to AstraZeneca.

In accordance with the China Amendment, once Falikang is fully operational, which commenced in January 2021, substantially all product sales will be made by Falikang directly to the distributors in China, while the Company continues to sell directly in few provinces in China. Revenue will be recognized upon the transfer of control of commercial drug product to Falikang. For the Company’s direct sales of commercial drug product, revenue will be recognized when control of the promised good is transferred to the customer in an amount that reflects the consideration to which the Company expects to be entitled to in exchange for the product.

Summary of revenue recognized under the collaboration agreements

The table below summarizes the accounting treatment for the various performance obligations pursuant to each of the Astellas and AstraZeneca agreements. License amounts identified below are included in the “License revenue” line item in the consolidated statements of operations. All other elements identified

below are included in the “Development and other revenue” line item in the consolidated statements of operations.

Amounts recognized as license revenue and development revenue under the Japan Agreement with Astellas were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020		2019		2018
Japan	License revenue	$	14,323	$	11,935	$	14,323
	Development revenue	$	1,220	$	1,222	$	2,400

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Japan Agreement, along with any associated deferred revenue as follows (in thousands):

Japan Agreement	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020		Total Consideration Through December 31, 2020
License	$	100,347	$	—	$	100,347
Development revenue		16,350		130		16,480
Total license and development revenue	$	116,697	$	130	$	116,827

The revenue recognized under the Japan Agreement for the year ended December 31, 2020 included an increase of $15.1 million resulting from changes to estimated variable consideration in the current year relating to performance obligations satisfied or partially satisfied in previous periods. The Company does not expect material variable consideration from estimated future co-development billing beyond development period in the transaction price related to the Japan Agreement.

Amounts recognized as license revenue and development revenue under the Europe Agreement with Astellas were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020		2019		2018
Europe	License revenue	$	—	$	117,470	$	—
	Development revenue	$	17,954	$	28,172	$	18,503

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Europe Agreement with Astellas, along with any associated deferred revenue as follows (in thousands):

Europe Agreement	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020		Total Consideration Through December 31, 2020
License	$	487,951	$	—	$	487,951
Development revenue		248,962		1,429		250,391
Total license and development revenue	$	736,913	$	1,429	$	738,342

The revenue recognized under the Europe Agreement for the year ended December 31, 2020 included an increase in revenue of $1.5 million resulting from changes to estimated variable consideration in the current year relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the Europe Agreement includes $27.6 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period.

Amounts recognized as license revenue and development revenue under the U.S./RoW and China Agreements with AstraZeneca were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020			2019		2018
U.S. / RoW and China	License revenue	$	—		$	47,681	$	7,946
	Development revenue		61,508			84,629		104,970
	China performance obligation	$	(90	)	$	90	$	—

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the U.S./RoW Agreement and China Agreement, along with any associated deferred revenue as follows (in thousands):

U.S. / RoW and China Agreements	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020			Total Consideration Through December 31, 2020
License	$	341,844	$	—		$	341,844
Co-development, information sharing & committee services		554,775		2,276			557,051
China performance obligation		—		137,338			137,338
Total license and development revenue	$	896,619	$	139,614	*	$	1,036,233

Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the consolidated balance sheets. As of December 31, 2020, deferred revenue included $137.5 million related to the U.S./RoW and China Agreement, which represents the net of $139.6 million of deferred revenue presented above and a $2.1 million unbilled co-development revenue under the China Amendment with AstraZeneca.

The revenue recognized under the U.S./RoW Agreement and China Agreement for the year ended December 31, 2020 included a reduction in revenue of $2.9 million resulting from changes to estimated variable consideration in the current year relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the U.S./RoW Agreement and China Agreement includes $37.9 million of variable consideration from estimated future co-development billing. The amount allocated to the U.S./RoW Agreement is expected to be recognized over the remaining development service period. The amount allocated to the China performance obligation is expected to be recognized as the Company transfers control of the commercial drug product to Falikang.

Product Revenue, Net

Product revenue from roxadustat commercial sales in China is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those products, net of various sales rebates and discounts. Product revenue, net was as follows (in thousands):

	Years Ended December 31,
	2020			2019
Gross revenue	$	89,027		$	2,803
Price adjustment		—			(936	)
Non-key account hospital listing award		(9,325	)		—
Contractual sales rebate		(6,189	)		(149	)
Other discounts and rebates		(923	)		(18	)
Sales return		(92	)		—
Product revenue, net	$	72,498		$	1,700

In the second quarter of 2020, the Company amended the agreement with its pharmaceutical distributors, which triggered accounting modifications particularly related to the non-key account hospital listing award. For the year ended December 31, 2020, the non-key account hospital listing award was $9.3 million, which was recorded as a reduction to the revenue and calculated based on eligible non-key account hospital listings to date achieved by each distributor with certain requirements met during the period.

For the year ended December 31, 2020 and 2019, the contractual sales rebate was $6.2 million and $0.1 million, respectively, which were calculated based on the stated percentage of gross sales by each distributor in the distribution agreement entered between FibroGen and each distributor. All other rebates and discounts, including sales return allowance were immaterial for the periods presented.

For the year ended December 31, 2019, a $0.9 million of price adjustment was recorded based on government-listed price guidance and estimated channel inventory levels.

The rebates and discounts that the Company’s pharmaceutical distributors have earned are eligible to be applied against future sales orders, limited to certain maximums until such rebates and discounts are exhausted. These rebates and discounts are recorded as contract liabilities at the time they become eligible in the same period that the related revenue is recorded. Due to the distributor’s legal right to offset, at each balance sheet date, the rebates and discounts are presented as reductions to gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The distributor’s legal right of offset is calculated at the individual distributor level. The following table includes a roll-forward of the related contract liabilities (in thousands):

Balance at

December 31, 2019

Additions

Deduction

Currency

Translation

and Other

Gross

Contract

Liabilities

Balance

Presented Net

Against

Accounts

Receivable

Balance at

December 31, 2020

Product revenue - Contract liabilities

(1,102

)

(16,497

)

2,184

(270

)

(15,685

)

548

(15,137

)

As of December 31, 2020, the total rebates and discounts as reductions to gross accounts receivable was $0.5 million, and the total contract liabilities was $15.1 million, which was included in accrued and other current liabilities in the consolidated balance sheet.

The reductions to gross accounts receivable, including the above-mentioned contra-accounts receivable items related to product revenue, totaled $0.8 million and $1.1 million as of December 31, 2020 and 2019, respectively.

Drug Product Revenue

Drug product revenue was as follows (in thousands):

	Years Ended December 31,
	2020		2019			2018
Astellas	$	4,281	$	(36,324	)	$	64,776
AstraZeneca		4,625		—			—
Drug product revenue	$	8,906	$	(36,324	)	$	64,776

The Company fulfilled all the shipment obligations under the term of the Japan Amendment during the year ended December 31, 2018, and recognized the related product revenue of $64.8 million in the same period based on a transaction price that was subject to potential future adjustments, which represented a form of variable consideration.

A change in estimated variable consideration incurred in 2019 related to the above API shipments in 2018, at the time the actual listed price for roxadustat was issued by the Japanese Ministry of Health, Labour and Welfare, which resulted in a total difference of $36.3 million between the estimated and the actual listed price and yield from the manufacture of bulk product tablets.

In addition, during the year ended December 31, 2020, the Company recorded another $4.0 million reduction to drug product revenue related to the above API shipments, due to a change in estimated variable consideration. Specifically, the change in estimated variable consideration was based on the API held by Astellas at March 31, 2020 adjusted to reflect the updated listed price for roxadustat issued by the Japanese Ministry of Health, Labour and Welfare and changes in the estimated bulk product strength mix intended to be manufactured by Astellas, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others.

During the second quarter of 2020, the Company fulfilled shipment obligations under the term of Japan Amendment with Astellas, and recognized related drug product revenue of $8.2 million in the same period.

During the fourth quarter of 2020, the Company shipped bulk drug product from process validation supplies for commercial purposes under the term of the Europe Agreement with Astellas. The Company constrained the consideration from this shipment due to a high degree of uncertainty associated to the final consideration. As a result, the Company recorded $1.4 million as current deferred revenue and $4.6 million as long-term deferred revenue as of December 31, 2020. The deferred revenue will be recognized as and when uncertainty is resolved. The following table includes a roll-forward of the related contract liabilities (in thousands):

Balance at

December 31, 2019

Additions

Balance at

December 31, 2020

Drug product revenue - Astellas - contract liabilities

—

(5,984

)

(5,984

)

During the year ended December 31, 2020, the Company shipped bulk drug product to AstraZeneca as pre-commercial supply for process validation purposes, under the term of Commercial Supply Agreement under the U.S./RoW Agreement with AstraZeneca, and recognized drug product revenue of $4.6 million.

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for each of the three years ended December 31, 2020.

Deferred Revenue

Deferred revenue represents amounts billed, or in certain cases, yet to be billed to the Company’s collaboration partners for which the related revenues have not been recognized because one or more of the revenue recognition criteria have not been met. The current portion of deferred revenue represents the amount to be recognized within one year from the balance sheet date based on the estimated performance period of the underlying performance obligations. The long-term portion of deferred revenue represents amounts to be recognized after one year through the end of the non-contingent performance period of the underlying performance obligations.

Deferred revenue includes amounts allocated to the China performance obligation under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China and to when the control of the manufactured commercial drug product is transferred to AstraZeneca. As of December 31, 2020, approximately $3.5 million of the deferred revenue related to the China unit of accounting was included in short-term deferred revenue, which represents the amount of deferred revenue associated with the China unit of accounting that is expected to be recognized within the next 12 months, associated with the commercial sales in China.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

5.	Fair Value Measurements

In accordance with the authoritative guidance on fair value measurements and disclosures under U.S. GAAP, the Company presents all financial assets and liabilities and any other assets and liabilities that are recognized or disclosed at fair value on a nonrecurring basis. The guidance defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles and expands disclosures about fair-value measurements. The guidance also requires fair value measurements be classified and disclosed in one of the following three categories:

Level 1: Quoted prices in active markets for identical assets or liabilities.

Level 2: Observable inputs other than quoted prices in active markets for identical assets or liabilities.

Level 3: Unobservable inputs.

The Company values certain assets and liabilities, focusing on the inputs used to measure fair value, particularly in instances where the measurement uses significant unobservable (Level 3) inputs. The Company’s financial instruments are valued using quoted prices in active markets (Level 1) or based upon other observable inputs (Level 2). The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and considers factors specific to the asset or liability. In addition, the categories presented do not suggest how prices may be affected by the size of the purchases or sales, particularly with the largest highly liquid financial issuers who are in markets continuously with non-equity instruments, or how any such financial assets may be impacted by other factors such as U.S. government guarantees. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The availability of observable data is monitored to assess appropriate classification of financial instruments within the fair value hierarchy. Depending upon the availability of such inputs, specific securities may transfer between levels. In such instances, the transfer is reported at the end of the reporting period.

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Bond and mutual funds	$	—	$	8,144	$	—	$	8,144
Equity investments		244		—		—		244
Money market funds		590,347		—		—		590,347
Total	$	590,591	$	8,144	$	—	$	598,735

	December 31, 2019
	Level 1		Level 2		Level 3		Total
U.S. treasury notes and bills	$	347,383	$	80,123	$	—	$	427,506
Bond and mutual funds		10,816		—		—		10,816
Equity investments		255		—		—		255
Money market funds		85,551		—		—		85,551
Certificate of deposit		—		30,032		—		30,032
Total	$	444,005	$	110,155	$	—	$	554,160

The Company’s Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs. There were no transfers of assets between levels for the years ended December 31, 2020 and 2018. During the fourth quarter of 2019, there was a $29.8 million transfer of assets from Level 1 to Level 2 as such US treasury notes and bills were changed to off-the-run when they were issued before the most recent issue and were still outstanding at measurement day.

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,141	$	1,141

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,544	$	1,544

The fair value of the Company’s financial liabilities were derived by using an income approach, which required Level 3 inputs such as discounted estimated future cash flows.

There were no transfers of liabilities between levels for the years ended December 31, 2020, 2019 and 2018.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

The Company currently has two building leases treated as finance leases.

In 2006, the Company entered into a long-term property lease with Alexandria for its corporate headquarters in San Francisco, California, with an initial term of 15 years, scheduled to expire in 2023. The Company has an option to extend the lease for an additional 10 years through 2033. The lease contract provides for a fixed annual rent, with scheduled increases of two percent that occur on each anniversary of the rent commencement date. This lease requires the Company to pay all costs of ownership, operation, and maintenance of the premises, including without limitation all operating costs, insurance costs, and taxes.

In 2013, the Company entered into a long-term property lease with Beijing Economic-Technological Development Area (“BDA”) Management Committee for a pilot plant located in Beijing Yizhuang Biomedical Park of BDA. The building is leased for an initial lease term of eight years, scheduled to expire in 2021. Renewal options are not specified within the lease contract. The lease contract provides for fixed quarterly rent payments, with scheduled increases that occur as detailed in the lease contract. This lease requires the Company to pay all operating and maintenance costs, and a fixed amount for property management fees.

The Company currently has six additional real estate leases for office spaces in Shanghai and Beijing, China, which are treated as operating leases. These leases have lease terms ranging from two to three years, expiring in 2023. These lease contracts provide for fixed quarterly rent payments, and require the Company to pay operating and maintenance costs, and a fixed amount for property management fees.

In addition, the Company has several immaterial lease arrangements in China and U.S. for office equipment, scientific devices and automobile leases, with contracted lease terms ranging from two to four years, treated as finance leases or operating leases, respectively.

The Company’s lease assets and related lease liabilities were as follows (in thousands):

		December 31,
	Balance Sheet Line Item	2020			2019
Assets
Finance:
Right-of-use assets - cost		$	50,477		$	49,909
Accumulated amortization			(20,871	)		(10,307	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		29,606			39,602
Operating:
Right-of-use assets - cost			3,934			2,736
Accumulated amortization			(1,891	)		(805	)
Operating lease right-of-use assets, net	Other assets		2,043			1,931
Total lease assets		$	31,649		$	41,533

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,330		$	12,351
Operating lease liabilities	Accrued and other current liabilities		1,188			983
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		25,391			37,610
Operating lease liabilities	Other long-term liabilities		853			942
Total lease liabilities		$	39,762		$	51,886

The components of lease expense were as follows (in thousands):

		Years Ended December 31,
	Statement of Operations Line Item	2020			2019
Finance lease cost:
Amortization of right-of-use assets	Cost of goods sold; Research and development; Selling, general and administrative expenses	$	10,369		$	10,307
Interest on lease liabilities	Interest expense		1,932			2,373
Operating lease cost	Cost of goods sold; Research and development; Selling, general and administrative expenses		1,151			891
Sublease income	Selling, general and administrative expenses		(1,201	)		(1,385	)
Total lease cost		$	12,251		$	12,186

Supplemental cash flow information related to leases were as follows (in thousands):

	Years Ended December 31,
	2020		2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	951	$	914
Operating cash flows from finance leases		1,896		2,196
Financing cash flows from finance leases		12,620		11,925
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		662		49,909
Operating leases	$	1,072	$	2,736

Lease term and discount rate were as follows:

	December 31,
	2020			2019
Weighted-average remaining lease term (years):
Finance leases		2.9			3.6
Operating leases		1.8			2.1
Weighted-average discount rate:
Finance leases		4.39	%		4.42	%
Operating leases		4.74	%		4.75	%

Maturities of lease liabilities as of December 31, 2020 are as follows (in thousands):

Year Ending December 31,	Finance Leases			Operating Leases
2021	$	13,689		$	1,142
2022		13,886			839
2023		12,526			143
Total future lease payments		40,101			2,124
Less: Interest		(2,380	)		(83	)
Present value of lease liabilities	$	37,721		$	2,041

Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

7.	Balance Sheet Components

Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	December 31,
	2020		2019
Cash	$	88,046	$	40,715
Money market funds		590,347		85,551
Total cash and cash equivalents	$	678,393	$	126,266

Investments

The Company’s investments consist of available-for-sale debt investments, marketable equity investments, term deposit and certificate of deposit. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major investments type are summarized in the tables below (in thousands):

	December 31, 2020
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Bond and mutual funds	$	8,147	$	—	$	(3	)	$	8,144
Equity investments		125		119		—			244
Total investments	$	8,272	$	119	$	(3	)	$	8,388

	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. treasury notes and bills	$	426,995	$	536	$	(25	)	$	427,506
Certificates of deposit		30,000		32		—			30,032
Bond and mutual funds		10,730		86		—			10,816
Equity investments		125		130		—			255
Total investments	$	467,850	$	784	$	(25	)	$	468,609

The contractual maturities of the available-for-sale investments were as follows (in thousands):

	December 31, 2020
Within one year - Bond and mutual funds	$	8,144
Equity investments		244
Total investments	$	8,388

The Company periodically reviews its available-for-sale investments and term deposit for other-than-temporary impairment. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the three years ended December 31, 2020, the Company did not recognize any other-than-temporary impairment loss.

Inventories

Inventories consisted of the following (in thousands):

	December 31,
	2020		2019
Raw materials	$	2,303	$	325
Work-in-progress		8,114		2,264
Finished goods		6,113		4,298
Total inventories	$	16,530	$	6,887

The Company started capitalizing inventory costs in June 2019 when FibroGen Beijing began productions of roxadustat for commercial sales purposes. The Company started capitalizing pre-launch inventory costs in the U.S. the second quarter of 2020 prior to regulatory approval. As of December 31, 2020, pre-launch inventory capitalized was 29% of the total inventory balance. The provision to write-down excess and obsolete inventory was nominal for the years ended December 31, 2020 and 2019.

Prepaid expenses and other current assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	December 31,
	2020			2019
Unbilled contract assets	$	2,147		$	180,000
Deferred revenues from associated contracts		(2,147	)		(54,790	)
Net unbilled contract assets		—			125,210
Prepaid assets		8,353			6,464
Other current assets		1,807			1,717
Total prepaid expenses and other current assets	$	10,160		$	133,391

The unbilled contract assets as of December 31, 2020 were related to unbilled co-development revenue under the China Amendment with AstraZeneca. The unbilled contract assets as of December 31, 2019 were related to two regulatory milestones totaling $130.0 million under the Europe Agreement with Astellas associated with the planned MAA submission in Europe, and a $50.0 million regulatory milestone under the U.S./RoW Agreement with AstraZeneca associated with the NDA submission in the U.S., which was submitted in December 2019 and accepted for review in February 2020. See Note 4, Collaboration Agreements and Revenues, for details.

Property and Equipment

Property and equipment consisted of the following (in thousands):

	December 31,
	2020			2019
Leasehold improvements	$	102,006		$	101,548
Laboratory equipment		18,143			17,329
Machinery		8,312			8,217
Computer equipment		9,545			8,399
Furniture and fixtures		6,128			5,822
Construction in progress		760			1,792
Total property and equipment	$	144,894		$	143,107
Less: accumulated depreciation		(111,247	)		(100,364	)
Property and equipment, net	$	33,647		$	42,743

Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $11.7 million, $11.1 million, and $6.6 million, respectively.

Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Preclinical and clinical trial accruals	$	44,113	$	16,279
API product price adjustment		—		36,324
Payroll and related accruals		22,800		19,784
Contract liabilities to pharmaceutical distributors		15,137		—
Accrued co-promotion expenses - current		11,537		—
Roxadustat profit share to AstraZeneca		7,007		—
Property taxes and other		5,970		2,044
Professional services		4,869		4,842
Other		8,088		4,543
Total accrued and other current liabilities	$	119,521	$	83,816

The API product price adjustment of $36.3 million accrued as of December 31, 2019 was related to the change in estimated variable consideration of API product at the time the roxadustat listed price was issued by the Japanese Ministry of Health, Labour and Welfare in the fourth quarter of 2019. This amount was fully paid during the first quarter of 2020. Refer to Note 4, Collaboration Agreements and Revenues, for details.

On July 8, 2020, the Parties entered into an amendment to the China Agreement, relating to the development and commercialization of roxadustat in China, which revised, among other things, the arrangements and calculation of the estimated co-promotion expenses payable to AstraZeneca for its sales and marketing efforts associated with the commercial sales for roxadustat in China. As a result, the previously accrued long-term co-promotion expenses were significantly reduced during the third quarter of 2020. $11.5 million of the recalculated accrued co-promotion expenses is anticipated to be paid within the next 12 months, therefore was recorded as a current liability as of December 31, 2020.

The profit share liability of $7.0 million to AstraZeneca as of December 31, 2020 represented the profit/loss share between FibroGen Beijing and AstraZeneca that is calculated pursuant to the China Agreement. This liability correspondingly reduced the deferred revenue related to the performance obligation in accordance with the China Agreement. Refer to Note 4, Collaboration Agreements and Revenues, for details.

Other Long-term Liabilities

Other long-term liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued long-term co-promotion expenses	$	27,424	$	53,071
Other long-term tax liabilities		8,675		8,913
Operating lease liabilities, non-current		853		942
Other		2,690		2,481
Total other long-term liabilities	$	39,642	$	65,407

The accrued long-term co-promotional expenses of $53.1 million as of December 31, 2019 was related to the estimated amount payable to AstraZeneca for its sales and marketing efforts related to the commercial launch for roxadustat in China. As mentioned above, the China Amendment revised the arrangements and calculation of the estimated co-promotion expenses payable to AstraZeneca. As a result, we reversed approximately $84.4 million of previously accrued long-term co-promotion expenses during the third quarter of 2020. $27.4 million of the recalculated accrued co-promotion expenses remained in the long-term liabilities as of December 31, 2020, as it is not anticipated to be paid within the next 12 months.

Product Development Obligations

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Product Development Obligations

8.	Product Development Obligations

The Technology Development Center of the Republic of Finland (“TEKES”) product development obligations consist of 11 separate advances (each in the form of a note agreement) received by FibroGen Europe between 1996 and 2008 from TEKES. These advances are granted on a project-by-project basis to fund various product development efforts undertaken by FibroGen Europe only. Each separate note is denominated in EUR and bears interest (not compounded) calculated as one percentage point less than the Bank of Finland rate in effect at the time of the note, but no less than 3.0%.

If the research work funded by TEKES does not result in an economically profitable business or does not meet its technological objectives, TEKES may, on application from FibroGen Europe, forgive each of these loans, including accrued interest, either in full or in part. As of December 31, 2020 and 2019, the Company had U.S. Dollar equivalent of $11.6 million and $10.6 million of principal outstanding, respectively, and $7.1 million and $6.2 million of interest accrued, respectively, which were presented in the product development obligations line on the consolidated balance sheets.

The Company is not a guarantor of these loans, and these loans are not repayable by FibroGen Europe until it has distributable funds.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

9.	Commitments and Contingencies

Contract Obligations

As of December 31, 2020, the Company had outstanding total non-cancelable purchase obligations of $86.0 million. The Company expects to fulfill our commitments under these agreements in the normal course of business, and as such, no liability has been recorded. The unconditional purchase obligations consisted of the following (in thousands):

	Purchase Obligations Due In The Year Ending December 31,
	2021		2022		Total
	(in thousands)
Manufacture and supply of roxadustat	$	14,114	$	10,951	$	25,065
Manufacture and supply of pamrevlumab		24,480		33,063		57,543
Other purchases		3,418		—		3,418
Total purchase obligations	$	42,012	$	44,014	$	86,026

Some of the Company’s license agreements provide for periodic maintenance fees over specified time periods, as well as payments by the Company upon the achievement of development, regulatory and commercial milestones. Future milestone payments for research and pre-clinical stage development programs consisted of up to approximately $10.9 million in total potential future milestone payments under the Company’s license agreements with Dana-Farber Cancer Institute, University of Miami and Medarex, Inc. These milestone payments generally become due and payable only upon the achievement of certain developmental, clinical, regulatory and/or commercial milestones. The event triggering such payment or obligation has not yet occurred.

Legal Proceedings

From time to time, the Company is a party to various legal actions, both inside and outside the U.S., arising in the ordinary course of its business or otherwise. The Company accrues amounts, to the extent they can be reasonably estimated, that the Company believes will result in a probable loss (including, among other things, probable settlement value), to adequately address any liabilities related to legal proceedings and other loss contingencies. A loss or a range of loss is disclosed when it is reasonably possible that a material loss will incur and can be estimated, or when it is reasonably possible that the amount of a loss, when material, will exceed the recorded provision.

On April 20, 2020, in response to an invalidation action brought against certain FibroGen United Kingdom patents by Akebia, the United Kingdom court handed down a decision invalidating United Kingdom designations of European Patent Nos. 1463823, 1633333, 2298301, 2322153, and 2322155. The United Kingdom designation to European Patent No. 2289531 was held to be valid in amended form, but not infringed by Akebia. The Company and its partner Astellas have filed an appeal of the decision in the United Kingdom Court of Appeal. The Company did not have material accruals for any currently active legal action in its consolidated balance sheets as of December 31, 2020, as it could not predict the ultimate outcome of these matters, or reasonably estimate the potential exposure.

Indemnification Agreements

The Company enters into standard indemnification arrangements in the ordinary course of business, including for example, service, manufacturing and collaboration agreements. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, including in connection with intellectual property infringement claims by any third party with respect to its technology. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the extent permissible under applicable law. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these arrangements is minimal.

Equity and Stock-based Compensation

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity and Stock-based Compensation

10.	Equity and Stock-based Compensation

Subsidiary Stock and Non-Controlling Interests

FibroGen Europe

As of December 31, 2020 and 2019, respectively, FibroGen Europe had a total of 42,619,022 shares of Preferred Stock outstanding, of which there were 1,700,845 shares of Series A Preferred Stock, 1,875,000 shares of Series B Preferred Stock, 1,599,503 shares of Series C Preferred Stock, 1,520,141 shares of Series D Preferred Stock, 459,565 shares of Series E Preferred Stock, 5,714,332 shares of Series F Preferred Stock, 9,927,500 shares of Series G Preferred Stock and 19,822,136 shares of Series H Preferred Stock, all of which shares no longer have any right to be exchanged for FibroGen, Inc. Common Stock. The holders of FibroGen Europe’s shares of Preferred Stock (“Preferred Shares”) have the following rights, preferences and privileges:

Dividend Rights — When the assets of FibroGen Europe are distributed (except for distribution in a liquidation), Preferred Shares shall have the same rights to dividend or other forms of distribution as shares of Common Stock of FibroGen Europe. In the event of a merger, holders of Preferred Shares do not have the right to demand FibroGen Europe to redeem all or part of their Preferred Shares. FibroGen Europe may repurchase shares of Common Stock or Preferred Shares for consideration.

Pre-emptive Right — Preferred Shares shall have pre-emptive subscription right in accordance with the Finnish Limited Liability Companies Act if additional shares are issued, option rights are given, or convertible loan is taken, provided, however, that the foregoing pre-emptive right does not apply to a directed share issue, for which two thirds (2/3) of the voting shares represented at a general meeting of shareholders approve for an important legitimate cause.

Redemption Right — If a Preferred Share can be redeemed by a majority shareholder owning more than ninety percent (90%) of the shares of FibroGen Europe in accordance with the provisions of the Finnish Limited Liability Companies Act, the minority holders of Preferred Shares have the right to request redemption of their shares.

Voting Right — Each share has one vote. Preferred Shares have voting rights only in situations that are specifically provided in the Articles of Association, which include a merger transaction and directed share issue. In addition, Preferred Shares have right to vote in a general shareholder meeting for amending the Articles of Association if the amendment will affect the rights of Preferred Shares.

Conversion Right (1-for-1 basis into Common Stock of FibroGen Europe):

•

Voluntary conversion right: Preferred Shares can be converted into common shares upon the written request of a shareholder provided that the conversion is feasible within the maximum and minimum amounts of shares of classes of FibroGen Europe as set forth in its Articles of Association. Such request can be withdrawn before the notification of conversion is filed with the Finnish Trade Register.

•

Compulsory conversion right: Preferred Shares will be converted into common shares if (i) FibroGen Europe’s shares are listed in a stock exchange or other trading system in the European Economic Area, or (ii) FibroGen Europe’s recombinant collagen and gelatin production technology is being put into commercial use in the area of Europe and certain other European states. Commercial use means there is income generated from the first commercial sale of the products incorporating the above mentioned technology and does not include license fees, development financing, milestone payments or income from test products or equipment used in research. The board of directors of FibroGen Europe shall notify the shareholders of the compulsory conversion in writing, and the shareholders shall request to convert their shares within the timeframe provided in the notification. Should the shareholders fail to make the conversion request within the time limit, FibroGen Europe may redeem the shares of such shareholders.

Liquidation Right — In the event of a dissolution of FibroGen Europe, holders of Preferred Shares are entitled to be paid in an amount equal to the subscription price of the shares before any distribution is made to holders of common shares. Among holders of Preferred Shares, holders of shares of Series F Preferred Stock are entitled to be paid in an amount equal to the subscription price of Series F Preferred Stock before any distribution is made to holders of other Preferred Shares.

FibroGen Cayman

FibroGen Cayman had 6,758,000 Series A Preference Shares outstanding as of December 31, 2020 and 2019, respectively. The holders of the FibroGen Cayman Series A Preference Shares have the following rights, preferences and privileges:

Liquidation — In the event of liquidation, dissolution, or winding up of the Company, either voluntary or involuntary, including by means of a merger, the holders of FibroGen Cayman Series A Preference Shares are entitled to be paid an amount equal to the product of the number of shares held by a holder of shares of FibroGen Cayman Series A Preference Shares and the original issue price of $1.00 (subject to equitable adjustment for any stock dividend, combination, split, reclassification, recapitalization) plus all declared and unpaid dividends thereon.

Conversion — Each share of FibroGen Cayman Series A Preference Shares is convertible into the number of fully paid and non-assessable shares of Common Stock of FibroGen Cayman that results from dividing the original issue price by the conversion price in effect at the time of the conversion, subject to adjustments for stock splits, stock dividends, reclassifications and like events. The FibroGen Cayman Series A Preference Shares have a conversion price that is equal to the original issuance price such that the conversion ratio to FibroGen Cayman Common Stock is 1:1 as of all periods presented.

Voting — The holders of FibroGen Cayman Series A Preference Shares are entitled to vote together with the FibroGen Cayman Common Stock holders on all matters submitted for a vote of the stockholders. The holder of each share of FibroGen Cayman Series A Preference Shares has the number of votes equal to the number of shares of FibroGen Cayman Common Stock into which it is convertible.

Dividends — The holders of FibroGen Cayman Series A Preference Shares are entitled to receive cash dividends when and if declared, at a rate of 6%.

Non-Controlling Interests

Non-controlling interest positions related to the issuance of subsidiary stock as described above are reported as a separate component of consolidated equity from the equity attributable to the Company’s stockholders at December 31, 2020 and 2019. In addition, the Company does not allocate losses to the non-controlling interests as the outstanding shares representing the non-controlling interest do not represent a residual equity interest in the subsidiary. Upon the initial public offering and as described above, all eligible FibroGen Europe preferred shares were exchanged for 958,996 shares of FibroGen Common Stock. No other FibroGen Europe shares have the right to be exchanged for FibroGen, Inc. Common Stock.

Common Stock

Each share of Common Stock is entitled to one vote. The holders of Common Stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding.

Shares of Common Stock outstanding, shares of stock plans outstanding and shares reserved for future issuance related to stock options and RSU grants and the Company’s Employee Stock Purchase Plan (“ESPP”) purchases are as follows (in thousands):

	December 31,
	2020		2019
Common stock outstanding		91,441		87,657
Stock options outstanding		9,290		10,018
RSUs outstanding		1,893		1,483
Shares reserved for future stock options and RSUs grant		7,910		7,725
Shares reserved for future ESPP offering		4,070		3,337
Total shares of common stock reserved		114,604		110,220

Stock Plans

Stock Option and RSU Plans

Under the Company’s Amended and Restated 2005 Stock Plan (“2005 Stock Plan”), the Company may issue shares of Common Stock and options to purchase Common Stock and other forms of equity incentives to employees, directors and consultants. Options granted under the 2005 Stock Plan may be incentive stock options or nonqualified stock options. Incentive stock options (“ISO”) may be granted only to employees and officers of the Company. Nonqualified stock options (“NSO”) and stock purchase rights may be granted to employees, directors and consultants. The board of directors has the authority to determine to whom options will be granted, the number of options, the term and the exercise price. Options are to be granted at an exercise price not less than fair market value for an ISO or an NSO. Options generally vest over four years. Options expire no more than 10 years after the date of grant. Upon the effective date of the registration statement related to the Company’s initial public offering, the 2005 Plan was amended to cease the grant of any additional awards thereunder, although the Company will continue to issue common stock upon the exercise of previously granted stock options under the 2005 Plan.

In September 2014, the Company adopted a 2014 Equity Incentive Plan (the “2014 Plan”) which became effective on November 13, 2014. The 2014 Plan is the successor equity compensation plan to the 2005 Plan. The 2014 Plan will terminate on November 12, 2024. The 2014 Plan provides for the grant of incentive stock options, nonqualified stock options, restricted stock awards, stock appreciation rights, performance stock awards, performance cash awards, restricted stock units and other stock awards to employees, directors and consultants. Stock options granted must be at prices not less than 100% of the fair market value at date of grant. Option vesting schedules are determined by the Company at the time of issuance and generally have a four year vesting schedule (25% vesting on the first anniversary of the vesting base date and quarterly thereafter over the next 3 years). Options generally expire ten years from the date of grant unless the optionee is a 10% stockholder, in which case the term will be five years from the date of grant. Unvested options exercised are subject to the Company’s repurchase right. Shares reserved for issuance increases on January 1 of each year commencing on January 1, 2016 and ending on January 1, 2024 by the lesser of (i) the amount equal to 4% of the number of shares issued and outstanding on December 31 immediately prior to the date of increase or (ii) such lower number of shares as may be determined by the board of directors. As of December 31, 2020, the Company has reserved 7,909,854 shares of its common stock that remains unissued for issuance under the 2014 Plan.

Issuance of shares upon share option exercise or share unit conversion is made through issuance of new shares authorized under the plan.

Certain Common Stock option holders have the right to exercise unvested options, subject to a right held by the Company to repurchase the stock, at the original exercise price, in the event of voluntary or involuntary termination of employment of the stockholder. The shares are generally released from repurchase provisions ratably over four years. The Company accounts for the cash received in consideration for the early exercised options as a liability. At December 31, 2020 and 2019, no shares of Common Stock were subject to repurchase by the Company.

Stock option transactions, including forfeited options granted under the 2014 Plan as well as prior plans, are summarized below:

	Shares (In thousands)			Weighted Average Exercise per Share		Weighted Average Remaining Contractual Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2019		10,018		$	26.63
Granted		2,692			31.55
Exercised		(3,113	)		10.73
Expired		(73	)		39.92
Forfeited		(234	)		40.11
Outstanding at December 31, 2020		9,290			32.94		6.60	$	86,013
Vested and expected to vest, December 31, 2020		8,929			32.76		6.50		84,125
Exercisable at December 31, 2020		5,576		$	29.50		5.10	$	66,943

The total intrinsic value of options exercised during the years ended December 31, 2020, 2019 and 2018 was $89.6 million, $59.2 million, and $97.5 million, respectively.

The following table summarizes RSU activity:

	Shares (In thousands)			Fair Value at Grant
Unvested at December 31, 2019		1,483		$	49.05
Granted		1,354			29.99
Vested		(813	)		45.55
Forfeited		(131	)		39.25
Unvested at December 31, 2020		1,893		$	37.60

Among the vested RSUs during the year ended December 31, 2020, 526,055 shares were released and issued, while the remaining was withheld for the related payroll taxes. The estimated weighted-average fair value of the awards granted during the years ended December 31, 2020, 2019 and 2018 was $29.99, $54.74 and $53.69, respectively.

ESPP

In September 2014, the Company adopted a 2014 ESPP that became effective on November 13, 2014. The 2014 ESPP is designed to enable eligible employees to periodically purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan or IRS limitations. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last day of the offering period. Purchases are accomplished through participation in discrete offering periods. The 2014 ESPP is intended to qualify as an ESPP under Section 423 of the Internal Revenue Code. The Company has reserved 1,600,000 shares of its common stock for issuance under the 2014 ESPP and shares reserved for issuance increases January 1 of each year commencing January 1, 2016 by the lesser of (i) a number of shares equal to 1% of the total number of outstanding shares of common stock on December 31 immediately prior to the date of increase; (ii) 1,200,000 shares or (iii) such number of shares as may be determined by the board of directors. There were 143,876 shares, 135,115 shares and 230,317 shares purchased by employees under the 2014 Purchased Plan for the years ended December 31, 2020, 2019 and 2018, respectively.

The expected term of 2014 ESPP shares is the average of the remaining purchase periods under each offering period.

Stock-Based Compensation

Stock-based compensation expense was recorded directly to research and development and selling, general and administrative expense for the years ended December 31, 2020, 2019 and 2018 was as follows (in thousands):

	Years Ended December 31,
	2020		2019		2018
Research and development	$	46,229	$	41,015	$	30,491
Selling, general and administrative		26,491		25,252		21,651
Total stock-based compensation expense	$	72,720	$	66,267	$	52,142

The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options is being amortized on a straight-line basis over the requisite service period of the awards. The fair market value of common stock is based on the closing price of the Company’s common stock as reported on the NASDAQ Global Select Market on the date of the grant.

The fair value of employee stock-based compensation is estimated using the following assumptions:

•

Expected Term. Expressed as a weighted-average, the expected life of the options is based on the average period the stock options are expected to be outstanding and was based on the Company’s historical information of the option exercise patterns and post-vesting termination behavior as well as contractual terms of the instruments.

•

Expected Volatility. The Company considers its historical volatility data for volatility considerations for its ESPP. Historically, the expected volatility for all other stock-based compensation was based upon a blend of the Company’s and comparable public entities’ historical volatility. Since the third quarter of 2020, the expected volatility for all other stock-based compensation is currently based upon the Company’s historical volatility data.

•	Risk-Free Interest Rate. Expressed as a weighted-average, the risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options.

•	Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future.

The assumptions used to estimate the fair value of stock options granted and ESPPs using the Black-Scholes option valuation model were as follows:

	Years Ended December 31,
	2020			2019			2018
Stock Options
Expected term (in years)		5.7			5.3			5.4
Expected volatility		67.1	%		68.0	%		67.9	%
Risk-free interest rate		0.8	%		2.4	%		2.7	%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	18.36		$	31.98		$	32.12

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	47.5 - 77.1		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	0.1 - 2.9		%	1.3 - 2.9		%	0.8 - 2.9		%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	17.53		$	19.27		$	16.27

As of December 31, 2020, there was $63.9 million of total unrecognized compensation costs, net of estimated forfeitures, related to non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period of 2.59 years. As of December 31, 2020, there was $55.5 million of total unrecognized compensation costs, net of estimated forfeitures, related to non-vested RSUs granted that will be recognized on a straight-line basis over the weighted-average period of 2.73 years.

Warrants

During the year ended December 31, 2019, a warrant to purchase 4,430 shares of our common stock was exercised and there was no warrant to purchase shares of Common Stock outstanding at December 31, 2020 and 2019.

Net Loss Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

11.	Net Loss Per Share

The following weighted impacts of outstanding securities were excluded from the calculation of diluted net loss per share because their effect would have been anti-dilutive for the three years presented (in thousands):

	Years Ended December 31,
	2020		2019		2018
Employee stock options		6,694		7,602		7,815
RSUs		564		1,187		820
ESPP		306		260		195
Warrants		—		1		4
		7,564		9,050		8,834

FibroGen, Inc. 401(k) Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

FibroGen, Inc. 401(k) Plan

12.	FibroGen, Inc. 401(k) Plan

Substantially all of the Company’s full-time U.S.-based employees are eligible to make contributions to the Company’s 401(k) Plan. Under this plan, participating employees may defer up to 60% of their pretax salary during the year, but not more than statutory limits. The Company may elect to match employee contributions. Matching contributions of $3.2 million, $3.0 million and $2.9 million were made during years ended December 31, 2020, 2019 and 2018, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

13.	Income Taxes

The components of loss before income taxes are as follows (in thousands):

	Years Ended December 31,
	2020			2019			2018
Domestic	$	(195,617	)	$	2,538		$	(38,472	)
Foreign		6,686			(79,180	)		(47,644	)
Loss before provision for income taxes	$	(188,931	)	$	(76,642	)	$	(86,116	)

The provision for income taxes consists of the following (in thousands):

	Years Ended December 31,
	2020		2019		2018
Current:
Federal	$	—	$	—	$	—
State		—		—		2
Foreign		360		328		302
Total current		360		328		304
Deferred:
Federal		—		—		—
State		—		—		—
Foreign		—		—		—
Total deferred		—		—		—
Total provision for income taxes	$	360	$	328	$	304

The following is the reconciliation between the statutory federal income tax rate and the Company’s effective tax rate:

	Years Ended December 31,
	2020			2019			2018
Tax at statutory federal rate		21.0	%		21.0	%		21.0	%
State tax		—	%		—	%		—	%
Stock-based compensation expense		2.4	%		6.3	%		14.5	%
Benefit due to intercompany transfer of assets		41.7	%		—	%		—	%
Valuation allowance on intercompany transfer of assets		(41.7	)%		—	%		—	%
Net operating losses not benefitted		(23.2	)%		(2.9	)%		(23.2	)%
Foreign net operating losses not benefitted		0.7	%		(21.7	)%		(11.6	)%
Deduction limitation on executive compensation		(0.8	)%		(2.5	)%		(0.5	)%
Other		(0.3	)%		(0.6	)%		(0.6	)%
Total		(0.2	)%		(0.4	)%		(0.4	)%

Significant components of the Company’s deferred tax assets are as follows (in thousands):

	December 31,
	2020			2019
Federal and state net operating loss carryforwards	$	134,033		$	91,267
Tax credit carryforwards		62,465			52,243
Foreign net operating loss carryforwards		32,417			37,786
Stock-based compensation		10,399			11,159
Lease obligations		8,243			10,698
Reserves and accruals		5,875			5,353
Deferred revenue		13,550			13,323
Intangible assets		75,915			—
Other		—			284
Subtotal		342,897			222,113
Less: Valuation allowance		(337,824	)		(213,847	)
Net deferred tax assets		5,073			8,266

Fixed assets		(5,073	)		(8,266	)
Other		—			—
Net deferred tax liabilities		(5,073	)		(8,266	)
Total net deferred tax assets	$	—		$	—

A valuation allowance has been provided to reduce the deferred tax assets to an amount management believes is more likely than not to be realized. Expected realization of the deferred tax assets for which a valuation allowance has not been recognized is based on upon the reversal of existing temporary differences and future taxable income.

The valuation allowance increased by $124.0 million, $19.9 million and $34.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. Due to uncertainty surrounding the realization of the favorable tax attributes in the future tax returns, the Company has established a valuation allowance against its otherwise recognizable net deferred tax assets.

During 2020, the Company transferred certain intellectual property rights relating to its Chinese business between its wholly owned subsidiaries that are based in different tax jurisdictions. The transferor entity was not subject to income taxes in its local jurisdiction. The acquiring entity of the intellectual property is entitled to amortize the acquisition price of the intangible assets for tax purposes. In accordance with ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory, the Company recognized a deferred tax asset of $78.7 million for the temporary difference arising from the acquirer’s excess tax basis. Furthermore, based upon the weight of available evidence, the Company recognized a full valuation allowance against this deferred tax asset since it does not currently believe that realization of this gross deductible temporary difference is more likely than not. Accordingly, this inter-company transfer did not have a material impact to the Company’s consolidated financial statements.

At December 31, 2020, the Company had net operating loss carryforwards available to offset future taxable income of approximately $606.8 million and $133.6 million for federal and state tax purposes, respectively. These carryforwards will begin to expire in 2026 for federal and 2021 for state purposes, if not utilized before these dates. The Company also had foreign net operating loss carryforwards of approximately $172.9 million which expire between 2021 and 2030 if not utilized.

At December 31, 2020, the Company had approximately $66.9 million of federal and $32.9 million of California research and development tax credit and other tax credit carryforwards available to offset future taxable income. The federal credits begin to expire in 2021 and the California research credits have no expiration dates.

Federal and state tax laws impose substantial restrictions on the utilization of net operating loss and credit carryforwards in the event of an “ownership change” for tax purposes, as defined in IRC Section 382. The Company reviewed its stock ownership for year ended December 31, 2020 and concluded no ownership changes occurred which would result in a reduction of its net operating loss or in its research and development credits expiring unused. If additional ownership change occurs, the utilization of net operating loss and credit carryforwards could be significantly reduced.

Uncertain Tax Positions

The Company had unrecognized tax benefits of approximately $48.6 million as of December 31, 2020. Approximately $0.5 million of unrecognized tax benefits, if recognized, would affect the effective tax rate. The interest accrued as of December 31, 2020 and 2019 was immaterial.

A reconciliation of the beginning and ending amounts of unrecognized income tax benefits during the three years ended December 31, 2020 is as follows (in thousands):

	Federal and State
Balance as of December 31, 2017	$	23,361
Increase due to prior positions		379
Increase due to current year position		4,216
Balance as of December 31, 2018		27,956
Decrease due to prior positions		(111	)
Increase due to current year position		4,418
Balance as of December 31, 2019		32,263
Decrease due to prior positions		(137	)
Increase due to current year position		16,448
Balance as of December 31, 2020	$	48,574

Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. The Company does not anticipate a material change to its unrecognized tax benefits over the next twelve months that would affect the Company’s effective tax rate.

The Company classifies interest and penalties as a component of tax expense, if any.

The Company files income tax returns in the U.S. federal jurisdiction, U.S. state and other foreign jurisdictions. The U.S. federal and U.S. state taxing authorities may choose to audit tax returns for tax years beyond the statute of limitation period due to significant tax attribute carryforwards from prior years, making adjustments only to carryforward attributes. The foreign statute of limitation generally remains open from 2011 to 2020. The Company is not currently under audit in any tax jurisdiction.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Related Party Transactions

12 Months Ended

Dec. 31, 2020

Related Party Transactions

14.	Related Party Transactions

Astellas is an equity investor in the Company and considered a related party. During the years ended December 31, 2020, 2019 and 2018, the Company recorded license and development revenue related to collaboration agreements with Astellas of $33.5 million, $158.8 million, and $35.2 million, respectively.

During the years ended December 31, 2020, 2019 and 2018, the Company also recorded drug product revenue from Astellas of $4.3 million, $(36.3) million, and $64.8 million, respectively. The drug product revenue from Astellas for the year ended December 31, 2020 included $8.2 million under the Japan Agreement, and a $4.0 million reduction to revenue as a change in estimated variable consideration at the time an updated listed price for roxadustat was issued by the Japanese Ministry of Health, Labour and Welfare related to roxadustat API sales in 2018. The drug product revenue from Astellas for the year ended December 31, 2019 included a change in estimated variable consideration that resulted in a $36.3 million reduction to revenue related to the product revenue of $64.8 million for API recorded in 2018. See Note 4, Collaboration Agreements and Revenues, for details.

During the years ended December 31, 2020, 2019 and 2018, the Company recorded expense related to collaboration agreements with Astellas of $0.5 million, $2.8 million and $1.5 million, respectively.

As of December 31, 2020 and 2019, accounts receivable from Astellas were $4.1 million and $4.8 million, respectively.

As of December 31, 2020 and 2019, total deferred revenue from Astellas were $7.5 million and $0.4 million, respectively.

As of December 31, 2019, prepaid expenses and other current assets from Astellas was $125.2 million of net unbilled contract assets, representing a $130.0 million unbilled contract asset related to two regulatory milestones under the Europe Agreement with Astellas associated with the planned MAA submission to the EMA, net of $4.8 million of associated deferred revenue. According to the Europe Agreement, this $130.0 million is not billable to Astellas until the submission of an MAA, therefore the net contract asset was included in the prepaid expenses and other current assets line on the Company’s consolidated balance sheet as of December 31, 2019. The $130.0 million was billed to Astellas upon the submission of an MAA in the second quarter of 2020. There was no such contract asset balance as of December 31, 2020. See Note 4, Collaboration Agreements and Revenues, for details.

As of December 31, 2020 and 2019, amounts due to Astellas were $1.1 million and $36.9 million, respectively. The amounts due are included in accrued liabilities and accounts payable on the consolidated balance sheets. The amount as of December 31, 2019 included the above-mentioned $36.3 million of a change in estimated variable consideration related to the API product revenue recognized in 2018, which was fully paid during the first quarter of 2020.

In September 2020, FibroGen Beijing and AstraZeneca completed the establishment of a jointly owned entity, Falikang, which was determined to be an unconsolidated VIE. As such, Falikang is accounted for as an equity method investment, and considered as a related party to the Company. The Company’s total investments in Falikang was approximately $2.8 million, which is the total of the 51.1% of Falikang’s equity and the acquisition costs. In addition, the Company recognized its proportionate share of the reported profits or losses of Falikang, beginning September 15, 2020, as other income (loss) in the consolidated statement of operations, and as an adjustment to its investment in unconsolidated subsidiary in the condensed consolidated balance sheet. Falikang has not incurred material profit or loss to date. As of December 31, 2020, the Company’s equity method investment in Falikang was $2.7 million, and prepaid expenses and other current assets included its miscellaneous receivables of $0.9 million from Falikang. See Note 3, Acquisition and Variable Interest Entity, for details.

Segment and Geographic Information

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Segment and Geographic Information

15.	Segment and Geographic Information

The Company has determined that the chief executive officer is the chief operating decision maker (“CODM”). The CODM reviews financial information presented for the Company’s various clinical trial programs as well as results on a consolidated basis. License revenues and development revenues received are not allocated to various programs for purposes of determining a profit measure and resource allocation decisions are made by the CODM based primarily on consolidated results. As such, the Company has concluded that it operates as one segment. Supplemental enterprise-wide information has been presented below.

Geographic Revenues

Geographic revenues, which are based on the bill-to region, are as follows (in thousands):

	Years Ended December 31,
	2020		2019		2018
Europe	$	67,161	$	132,400	$	112,916
Japan		36,660		122,475		100,002
China		72,498		1,700		—
All other		—		2		40
Total revenue	$	176,319	$	256,577	$	212,958

Geographic Assets

Inventory by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	4,715	$	—
China		11,815		6,887
Total inventory	$	16,530	$	6,887

Property and equipment, net by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	20,673	$	27,325
China		12,974		15,418
Total property and equipment	$	33,647	$	42,743

Finance lease right-of-use assets and operating lease right-of-use assets, net by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	29,551	$	39,237
China		55		365
Total finance lease right-of-use assets	$	29,606	$	39,602

United States	$	47	$	75
China		1,996		1,856
Total operating lease right-of-use assets	$	2,043	$	1,931

Customer Concentration

The Company’s revenues to date have been generated from the following collaboration partners that respectively accounted for 10% or more of the Company’s total revenue and accounts receivable:

	Percentage of Revenue									Percentage of Accounts Receivable
	Years Ended December 31,									December 31,
	2020			2019			2018			2020			2019
Astellas—Related party		21	%		48	%		47	%		10	%		17	%
AstraZeneca		37	%		52	%		53	%		26	%		81	%

The Company started selling roxadustat in China since late 2019 through a growing number of pharmaceutical distributors located in China. For the year ended December 31, 2020, the aggregate revenue from distributors represented 42% of the consolidated revenue, with no individual distributor representing over 10% of the total revenue. As of December 31, 2020, the aggregate accounts receivable from distributors represented 64% of the consolidated accounts receivable, with no material balance from any individual distributor. The aggregate revenue from distributors for the year ended December 31, 2019 and the aggregate accounts receivable from distributors as of December 31, 2019 were immaterial.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8657-108599

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-URI http://asc.fasb.org/topic&trid=2134510

+ Details

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2020

Valuation And Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

Schedule II: Valuation and Qualifying Accounts

(in thousands)

					Charged
			Charged		to Other
	Balance at		(Credited)		Accounts -
	Beginning of		to Statement		Liabilities			Deductions,			Balance at
	Year		of Operation		and Equity			Net			End of Year
Valuation allowances for deferred tax assets
Year ended December 31, 2020	$	213,847	$	123,977	$	—		$	—		$	337,824
Year ended December 31, 2019	$	193,987	$	19,860	$	—		$	—		$	213,847
Year ended December 31, 2018	$	159,540	$	34,447	$	—		$	—		$	193,987

Allowances for rebates and discounts
Year ended December 31, 2020	$	1,102	$	16,497	$	(14,867	)	$	(2,184	)	$	548
Year ended December 31, 2019	$	-	$	1,102	$	—		$	—		$	1,102

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

The Company operates in one segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs.

Variable Interest Entity

Foreign Currency Translation

The reporting currency of the Company and its subsidiaries is the U.S. dollar.

Use of Estimates

Concentration of Credit Risk

	December 31,
	2020			2019
Astellas Pharma Inc. (“Astellas”)—Related party		10	%		17	%
AstraZeneca AB (“AstraZeneca”)		26	%		81	%

Other Risks and Uncertainties

Cash, Cash Equivalents and Restricted Time Deposits

Investments

Fair Value of Financial Instruments

Trade Accounts Receivable

Trade accounts receivable

Credit Losses – Available-for-sale Debt Securities

Credit losses – Available-for-sale debt securities

Inventories

Property and Equipment

Leases

Impairment of Long-Lived Assets

Revenue Recognition

Revenues under collaboration agreements

Drug product revenue

Product revenue, net

Product revenue is recorded at the net sales prices (transaction price) which includes the following estimates of variable consideration:

•

•	Transfer fee discount: The transfer fee discount is offered to a distributor who has its downstream distributors supply to eligible hospitals. This discount is calculated based on a percentage of gross sales made to the downstream distributors, and recorded as a reduction to revenue as incurred;

•	Sales return: Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date; and

•

Research and Development Expenses

Clinical Trial Accruals

Selling, General and Administrative Expenses

Income Taxes

The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the Consolidated Statements of Operations.

Stock-Based Compensation

The fair value of employee stock-based compensation is estimated using the following assumptions:

•

•	Risk-Free Interest Rate. Expressed as a weighted-average, the risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options.

•	Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future.

Comprehensive Income (Loss)

Recently Issued and Adopted Accounting Guidance

Recently Issued Accounting Guidance Not Yet Adopted

Collaboration Arrangements and Revenues

Astellas Agreements

Japan Agreement

In 2018, FibroGen and Astellas entered into an amendment to the Japan Agreement that allows Astellas to manufacture roxadustat drug product for commercialization in Japan (the “Japan Amendment”). Under this amendment, FibroGen would continue to manufacture and supply roxadustat API to Astellas for the roxadustat commercial launch in Japan. The commercial terms of the Japan Agreement relating to the transfer price for roxadustat for commercial use remain substantially the same, reflecting an adjustment for the manufacture of drug product by Astellas rather than FibroGen. The Company fulfilled shipment obligations under the term of the Japan Amendment in the second quarter of 2020 and in 2018. The related drug product revenue, as described in details under Drug Product Revenue section below, were $4.3 million, $(36.3) million and $64.8 million in the years ended December 31, 2020, 2019 and 2018, respectively.

Europe Agreement

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

In 2020, the Company entered into Commercial Supply Agreement under the U.S./RoW Agreement with AstraZeneca to define general forecast, order, supply and payment terms for AstraZeneca to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The Company shipped bulk drug product to AstraZeneca as pre-commercial supply for process validation purposes during the year ended December 31, 2020 and recognized related drug product revenue of $4.6 million, as described in details under Drug Product Revenue section below.

China Agreement

China Amendment

As a result, the interim period primarily includes the following activities:

•

Accounting for the Astellas Agreements

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

(2)

(3)	License to the Company’s technology developed during the term of the agreement and development (referred to as “when and if available”) and information sharing services. These promises are generally satisfied throughout the term of the agreements.

(4)	Manufacturing of clinical supplies of products. This promise is satisfied as supplies for clinical product are delivered for use in the Company’s clinical trial programs during the development period, or pre-commercialization period.

(5)	Committee service. This promise is satisfied throughout the course of the agreements as meetings are attended.

(6)

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and records an adjustment to revenue, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known.

Accounting for the AstraZeneca Agreements

1.	While the two agreements were largely negotiated separately, those negotiations proceeded concurrently, and were intended to be completed contemporaneously, presuming AstraZeneca decided to proceed with licenses in all regions available.

Promised services that were not distinct have been combined with other promised services to form a distinct bundle of promised services, with revenue being recognized on the bundle of services rather than the individual promised services. There are no right-of-return provisions for the delivered items in the AstraZeneca agreements.

U.S./RoW Agreement:

The promised services that were analyzed, along with their general timing of satisfaction and recognition as revenue, are as follows:

(1)

(2)

(3)	Manufacturing of clinical supplies of products. This promise is satisfied as supplies for clinical product are delivered for use in the Company’s clinical trial programs during the development period, or pre-commercialization period.

(4)	Information sharing and committee service. These promises are satisfied throughout the course of the agreement as services are provided.

(5)

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the drug product revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgment. The Company reviews new information that may affect its variable consideration estimate at every reporting period and records an adjustment to revenue, if certain and material. Actual amounts of consideration ultimately received in the future may differ from the Company’s estimates, for which the Company will adjust these estimates and affect the drug product revenue in the period such variances become known.

China Agreement:

•

Product Revenue, Net

	Years Ended December 31,
	2020			2019
Gross revenue	$	89,027		$	2,803
Price adjustment		—			(936	)
Non-key account hospital listing award		(9,325	)		—
Contractual sales rebate		(6,189	)		(149	)
Other discounts and rebates		(923	)		(18	)
Sales return		(92	)		—
Product revenue, net	$	72,498		$	1,700

For the year ended December 31, 2019, a $0.9 million of price adjustment was recorded based on government-listed price guidance and estimated channel inventory levels.

Balance at

December 31, 2019

Additions

Deduction

Currency

Translation

and Other

Gross

Contract

Liabilities

Balance

Presented Net

Against

Accounts

Receivable

Balance at

December 31, 2020

Product revenue - Contract liabilities

(1,102

)

(16,497

)

2,184

(270

)

(15,685

)

548

(15,137

)

Drug Product Revenue

Drug product revenue was as follows (in thousands):

	Years Ended December 31,
	2020		2019			2018
Astellas	$	4,281	$	(36,324	)	$	64,776
AstraZeneca		4,625		—			—
Drug product revenue	$	8,906	$	(36,324	)	$	64,776

Balance at

December 31, 2019

Additions

Balance at

December 31, 2020

Drug product revenue - Astellas - contract liabilities

—

(5,984

)

(5,984

)

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for each of the three years ended December 31, 2020.

Deferred Revenue

Fair Value Measurements

Level 1: Quoted prices in active markets for identical assets or liabilities.

Level 2: Observable inputs other than quoted prices in active markets for identical assets or liabilities.

Level 3: Unobservable inputs.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Significant Balance of Accounts Receivable

The Company has not experienced any loss on its deposits of cash and cash equivalents. Included in current assets are significant balances of accounts receivable as follows:

	December 31,
	2020			2019
Astellas Pharma Inc. (“Astellas”)—Related party		10	%		17	%
AstraZeneca AB (“AstraZeneca”)		26	%		81	%

Acquisition and Variable Interest Entity (Tables)

12 Months Ended

Dec. 31, 2020

Acquisition And Variable Interest Entity [Abstract]

Summary of Equity Method Investment

The Company’s equity method investment in Falikang was as follows for the year ended December 31, 2020 (in thousands):

Entity

Ownership Percentage

Balance at

December 31, 2019

Additions

Share of Net Loss

Currency

Translation

Balance at

December 31, 2020

Falikang

51.1

—

2,825

(202

)

105

2,728

Collaboration Agreements and Revenues (Tables)

12 Months Ended

Dec. 31, 2020

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

Product revenue, net was as follows (in thousands):

	Years Ended December 31,
	2020			2019
Gross revenue	$	89,027		$	2,803
Price adjustment		—			(936	)
Non-key account hospital listing award		(9,325	)		—
Contractual sales rebate		(6,189	)		(149	)
Other discounts and rebates		(923	)		(18	)
Sales return		(92	)		—
Product revenue, net	$	72,498		$	1,700

Roll-forward of Related Contract Liabilities

. The following table includes a roll-forward of the related contract liabilities (in thousands):

Balance at

December 31, 2019

Additions

Deduction

Currency

Translation

and Other

Gross

Contract

Liabilities

Balance

Presented Net

Against

Accounts

Receivable

Balance at

December 31, 2020

Product revenue - Contract liabilities

(1,102

)

(16,497

)

2,184

(270

)

(15,685

)

548

(15,137

)

Schedule of Drug Product Revenue

Drug product revenue was as follows (in thousands):

	Years Ended December 31,
	2020		2019			2018
Astellas	$	4,281	$	(36,324	)	$	64,776
AstraZeneca		4,625		—			—
Drug product revenue	$	8,906	$	(36,324	)	$	64,776

Drug Product Revenue [Member]

Roll-forward of Related Contract Liabilities

The following table includes a roll-forward of the related contract liabilities (in thousands):

Balance at

December 31, 2019

Additions

Balance at

December 31, 2020

Drug product revenue - Astellas - contract liabilities

—

(5,984

)

(5,984

)

Japan [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement

Amounts recognized as license revenue and development revenue under the Japan Agreement with Astellas were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020		2019		2018
Japan	License revenue	$	14,323	$	11,935	$	14,323
	Development revenue	$	1,220	$	1,222	$	2,400

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

Japan Agreement	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020		Total Consideration Through December 31, 2020
License	$	100,347	$	—	$	100,347
Development revenue		16,350		130		16,480
Total license and development revenue	$	116,697	$	130	$	116,827

Europe [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement

Amounts recognized as license revenue and development revenue under the Europe Agreement with Astellas were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020		2019		2018
Europe	License revenue	$	—	$	117,470	$	—
	Development revenue	$	17,954	$	28,172	$	18,503

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

Europe Agreement	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020		Total Consideration Through December 31, 2020
License	$	487,951	$	—	$	487,951
Development revenue		248,962		1,429		250,391
Total license and development revenue	$	736,913	$	1,429	$	738,342

U.S./RoW and China [Member]

Summary of License Revenue and Development Revenue Recognized under Agreement

Amounts recognized as license revenue and development revenue under the U.S./RoW and China Agreements with AstraZeneca were as follows (in thousands):

		Years Ended December 31,
Agreement	Performance Obligation	2020			2019		2018
U.S. / RoW and China	License revenue	$	—		$	47,681	$	7,946
	Development revenue		61,508			84,629		104,970
	China performance obligation	$	(90	)	$	90	$	—

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue and Product Revenue Net

U.S. / RoW and China Agreements	Cumulative Revenue Through December 31, 2020		Deferred Revenue at December 31, 2020			Total Consideration Through December 31, 2020
License	$	341,844	$	—		$	341,844
Co-development, information sharing & committee services		554,775		2,276			557,051
China performance obligation		—		137,338			137,338
Total license and development revenue	$	896,619	$	139,614	*	$	1,036,233

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Values of Financial Assets Measured on Recurring Basis

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Bond and mutual funds	$	—	$	8,144	$	—	$	8,144
Equity investments		244		—		—		244
Money market funds		590,347		—		—		590,347
Total	$	590,591	$	8,144	$	—	$	598,735

	December 31, 2019
	Level 1		Level 2		Level 3		Total
U.S. treasury notes and bills	$	347,383	$	80,123	$	—	$	427,506
Bond and mutual funds		10,816		—		—		10,816
Equity investments		255		—		—		255
Money market funds		85,551		—		—		85,551
Certificate of deposit		—		30,032		—		30,032
Total	$	444,005	$	110,155	$	—	$	554,160

Fair Values of Financial Liabilities Carried at Historical Cost

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,141	$	1,141

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,544	$	1,544

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Schedule of Lease Assets and Related Lease Liabilities

The Company’s lease assets and related lease liabilities were as follows (in thousands):

		December 31,
	Balance Sheet Line Item	2020			2019
Assets
Finance:
Right-of-use assets - cost		$	50,477		$	49,909
Accumulated amortization			(20,871	)		(10,307	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		29,606			39,602
Operating:
Right-of-use assets - cost			3,934			2,736
Accumulated amortization			(1,891	)		(805	)
Operating lease right-of-use assets, net	Other assets		2,043			1,931
Total lease assets		$	31,649		$	41,533

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,330		$	12,351
Operating lease liabilities	Accrued and other current liabilities		1,188			983
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		25,391			37,610
Operating lease liabilities	Other long-term liabilities		853			942
Total lease liabilities		$	39,762		$	51,886

Components of Lease Expense

The components of lease expense were as follows (in thousands):

		Years Ended December 31,
	Statement of Operations Line Item	2020			2019
Finance lease cost:
Amortization of right-of-use assets	Cost of goods sold; Research and development; Selling, general and administrative expenses	$	10,369		$	10,307
Interest on lease liabilities	Interest expense		1,932			2,373
Operating lease cost	Cost of goods sold; Research and development; Selling, general and administrative expenses		1,151			891
Sublease income	Selling, general and administrative expenses		(1,201	)		(1,385	)
Total lease cost		$	12,251		$	12,186

Schedule of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases were as follows (in thousands):

	Years Ended December 31,
	2020		2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	951	$	914
Operating cash flows from finance leases		1,896		2,196
Financing cash flows from finance leases		12,620		11,925
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		662		49,909
Operating leases	$	1,072	$	2,736

Schedule of Lease Term and Discount Rate

Lease term and discount rate were as follows:

	December 31,
	2020			2019
Weighted-average remaining lease term (years):
Finance leases		2.9			3.6
Operating leases		1.8			2.1
Weighted-average discount rate:
Finance leases		4.39	%		4.42	%
Operating leases		4.74	%		4.75	%

Schedule of Maturities of Finance and Operating Leases Liabilities

Maturities of lease liabilities as of December 31, 2020 are as follows (in thousands):

Year Ending December 31,	Finance Leases			Operating Leases
2021	$	13,689		$	1,142
2022		13,886			839
2023		12,526			143
Total future lease payments		40,101			2,124
Less: Interest		(2,380	)		(83	)
Present value of lease liabilities	$	37,721		$	2,041

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	December 31,
	2020		2019
Cash	$	88,046	$	40,715
Money market funds		590,347		85,551
Total cash and cash equivalents	$	678,393	$	126,266

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments

	December 31, 2020
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Bond and mutual funds	$	8,147	$	—	$	(3	)	$	8,144
Equity investments		125		119		—			244
Total investments	$	8,272	$	119	$	(3	)	$	8,388

	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. treasury notes and bills	$	426,995	$	536	$	(25	)	$	427,506
Certificates of deposit		30,000		32		—			30,032
Bond and mutual funds		10,730		86		—			10,816
Equity investments		125		130		—			255
Total investments	$	467,850	$	784	$	(25	)	$	468,609

Summary of Contractual Maturities of Available-for-Sale Investments

The contractual maturities of the available-for-sale investments were as follows (in thousands):

	December 31, 2020
Within one year - Bond and mutual funds	$	8,144
Equity investments		244
Total investments	$	8,388

Schedule of Inventory

Inventories consisted of the following (in thousands):

	December 31,
	2020		2019
Raw materials	$	2,303	$	325
Work-in-progress		8,114		2,264
Finished goods		6,113		4,298
Total inventories	$	16,530	$	6,887

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	December 31,
	2020			2019
Unbilled contract assets	$	2,147		$	180,000
Deferred revenues from associated contracts		(2,147	)		(54,790	)
Net unbilled contract assets		—			125,210
Prepaid assets		8,353			6,464
Other current assets		1,807			1,717
Total prepaid expenses and other current assets	$	10,160		$	133,391

Schedule of Property and Equipment

Property and equipment consisted of the following (in thousands):

	December 31,
	2020			2019
Leasehold improvements	$	102,006		$	101,548
Laboratory equipment		18,143			17,329
Machinery		8,312			8,217
Computer equipment		9,545			8,399
Furniture and fixtures		6,128			5,822
Construction in progress		760			1,792
Total property and equipment	$	144,894		$	143,107
Less: accumulated depreciation		(111,247	)		(100,364	)
Property and equipment, net	$	33,647		$	42,743

Schedule of Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Preclinical and clinical trial accruals	$	44,113	$	16,279
API product price adjustment		—		36,324
Payroll and related accruals		22,800		19,784
Contract liabilities to pharmaceutical distributors		15,137		—
Accrued co-promotion expenses - current		11,537		—
Roxadustat profit share to AstraZeneca		7,007		—
Property taxes and other		5,970		2,044
Professional services		4,869		4,842
Other		8,088		4,543
Total accrued and other current liabilities	$	119,521	$	83,816

Schedule of Other Long-term Liabilities

Other long-term liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued long-term co-promotion expenses	$	27,424	$	53,071
Other long-term tax liabilities		8,675		8,913
Operating lease liabilities, non-current		853		942
Other		2,690		2,481
Total other long-term liabilities	$	39,642	$	65,407

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Summary of Unconditional Purchase Obligations

The unconditional purchase obligations consisted of the following (in thousands):

	Purchase Obligations Due In The Year Ending December 31,
	2021		2022		Total
	(in thousands)
Manufacture and supply of roxadustat	$	14,114	$	10,951	$	25,065
Manufacture and supply of pamrevlumab		24,480		33,063		57,543
Other purchases		3,418		—		3,418
Total purchase obligations	$	42,012	$	44,014	$	86,026

Equity and Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Common Stock Reserved for Future Issuance

	December 31,
	2020		2019
Common stock outstanding		91,441		87,657
Stock options outstanding		9,290		10,018
RSUs outstanding		1,893		1,483
Shares reserved for future stock options and RSUs grant		7,910		7,725
Shares reserved for future ESPP offering		4,070		3,337
Total shares of common stock reserved		114,604		110,220

Summary of Stock Option Transactions

Stock option transactions, including forfeited options granted under the 2014 Plan as well as prior plans, are summarized below:

	Shares (In thousands)			Weighted Average Exercise per Share		Weighted Average Remaining Contractual Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2019		10,018		$	26.63
Granted		2,692			31.55
Exercised		(3,113	)		10.73
Expired		(73	)		39.92
Forfeited		(234	)		40.11
Outstanding at December 31, 2020		9,290			32.94		6.60	$	86,013
Vested and expected to vest, December 31, 2020		8,929			32.76		6.50		84,125
Exercisable at December 31, 2020		5,576		$	29.50		5.10	$	66,943

Summary of RSU Activity

The following table summarizes RSU activity:

	Shares (In thousands)			Fair Value at Grant
Unvested at December 31, 2019		1,483		$	49.05
Granted		1,354			29.99
Vested		(813	)		45.55
Forfeited		(131	)		39.25
Unvested at December 31, 2020		1,893		$	37.60

Schedule of Recorded Stock-Based Compensation Expense

	Years Ended December 31,
	2020		2019		2018
Research and development	$	46,229	$	41,015	$	30,491
Selling, general and administrative		26,491		25,252		21,651
Total stock-based compensation expense	$	72,720	$	66,267	$	52,142

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Employee Stock Purchase Plans

The assumptions used to estimate the fair value of stock options granted and ESPPs using the Black-Scholes option valuation model were as follows:

	Years Ended December 31,
	2020			2019			2018
Stock Options
Expected term (in years)		5.7			5.3			5.4
Expected volatility		67.1	%		68.0	%		67.9	%
Risk-free interest rate		0.8	%		2.4	%		2.7	%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	18.36		$	31.98		$	32.12

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	47.5 - 77.1		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	0.1 - 2.9		%	1.3 - 2.9		%	0.8 - 2.9		%
Expected dividend yield		—			—			—
Weighted average estimated fair value	$	17.53		$	19.27		$	16.27

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share

	Years Ended December 31,
	2020		2019		2018
Employee stock options		6,694		7,602		7,815
RSUs		564		1,187		820
ESPP		306		260		195
Warrants		—		1		4
		7,564		9,050		8,834

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Loss Before Income Taxes

The components of loss before income taxes are as follows (in thousands):

	Years Ended December 31,
	2020			2019			2018
Domestic	$	(195,617	)	$	2,538		$	(38,472	)
Foreign		6,686			(79,180	)		(47,644	)
Loss before provision for income taxes	$	(188,931	)	$	(76,642	)	$	(86,116	)

Schedule of Components of Provision For Income Taxes

The provision for income taxes consists of the following (in thousands):

	Years Ended December 31,
	2020		2019		2018
Current:
Federal	$	—	$	—	$	—
State		—		—		2
Foreign		360		328		302
Total current		360		328		304
Deferred:
Federal		—		—		—
State		—		—		—
Foreign		—		—		—
Total deferred		—		—		—
Total provision for income taxes	$	360	$	328	$	304

Schedule of Reconciliation Between Statutory Federal Income Tax Rate and Effective Tax Rate

The following is the reconciliation between the statutory federal income tax rate and the Company’s effective tax rate:

	Years Ended December 31,
	2020			2019			2018
Tax at statutory federal rate		21.0	%		21.0	%		21.0	%
State tax		—	%		—	%		—	%
Stock-based compensation expense		2.4	%		6.3	%		14.5	%
Benefit due to intercompany transfer of assets		41.7	%		—	%		—	%
Valuation allowance on intercompany transfer of assets		(41.7	)%		—	%		—	%
Net operating losses not benefitted		(23.2	)%		(2.9	)%		(23.2	)%
Foreign net operating losses not benefitted		0.7	%		(21.7	)%		(11.6	)%
Deduction limitation on executive compensation		(0.8	)%		(2.5	)%		(0.5	)%
Other		(0.3	)%		(0.6	)%		(0.6	)%
Total		(0.2	)%		(0.4	)%		(0.4	)%

Schedule of Significant Components of Deferred Tax Assets

Significant components of the Company’s deferred tax assets are as follows (in thousands):

	December 31,
	2020			2019
Federal and state net operating loss carryforwards	$	134,033		$	91,267
Tax credit carryforwards		62,465			52,243
Foreign net operating loss carryforwards		32,417			37,786
Stock-based compensation		10,399			11,159
Lease obligations		8,243			10,698
Reserves and accruals		5,875			5,353
Deferred revenue		13,550			13,323
Intangible assets		75,915			—
Other		—			284
Subtotal		342,897			222,113
Less: Valuation allowance		(337,824	)		(213,847	)
Net deferred tax assets		5,073			8,266

Fixed assets		(5,073	)		(8,266	)
Other		—			—
Net deferred tax liabilities		(5,073	)		(8,266	)
Total net deferred tax assets	$	—		$	—

Schedule of Reconciliation of the Beginning and Ending Amounts of Unrecognized Income Tax Benefits

A reconciliation of the beginning and ending amounts of unrecognized income tax benefits during the three years ended December 31, 2020 is as follows (in thousands):

	Federal and State
Balance as of December 31, 2017	$	23,361
Increase due to prior positions		379
Increase due to current year position		4,216
Balance as of December 31, 2018		27,956
Decrease due to prior positions		(111	)
Increase due to current year position		4,418
Balance as of December 31, 2019		32,263
Decrease due to prior positions		(137	)
Increase due to current year position		16,448
Balance as of December 31, 2020	$	48,574

Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of Revenue by Geographic Area

Geographic revenues, which are based on the bill-to region, are as follows (in thousands):

	Years Ended December 31,
	2020		2019		2018
Europe	$	67,161	$	132,400	$	112,916
Japan		36,660		122,475		100,002
China		72,498		1,700		—
All other		—		2		40
Total revenue	$	176,319	$	256,577	$	212,958

Schedule of Inventory by Geographic Area

Inventory by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	4,715	$	—
China		11,815		6,887
Total inventory	$	16,530	$	6,887

Schedule of Long Lived Assets by Geographic Area

Property and equipment, net by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	20,673	$	27,325
China		12,974		15,418
Total property and equipment	$	33,647	$	42,743

Summary of Finance and Operating Lease Right of Use Assets by Geographical Location

Finance lease right-of-use assets and operating lease right-of-use assets, net by geographic location are as follows (in thousands):

	December 31,
	2020		2019
United States	$	29,551	$	39,237
China		55		365
Total finance lease right-of-use assets	$	29,606	$	39,602

United States	$	47	$	75
China		1,996		1,856
Total operating lease right-of-use assets	$	2,043	$	1,931

Schedule of Customer Concentration by Collaboration Partners

The Company’s revenues to date have been generated from the following collaboration partners that respectively accounted for 10% or more of the Company’s total revenue and accounts receivable:

	Percentage of Revenue									Percentage of Accounts Receivable
	Years Ended December 31,									December 31,
	2020			2019			2018			2020			2019
Astellas—Related party		21	%		48	%		47	%		10	%		17	%
AstraZeneca		37	%		52	%		53	%		26	%		81	%

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($) Segment	Apr. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)
Accounting Policy [Line Items]
Number of operating segment \| Segment	1
Currency translation adjustment		$ 1,300,000
Highly liquid investment maturity period	three months or less
Restricted time deposits	$ 2,072,000		$ 2,072,000
Cash and cash equivalents	$ 678,393,000		126,266,000
Short term investments maturity	12 months
Long term Investments Maturity	12 months
Impairment of long-lived assets	$ 0
Description of payment term	The period between the transfer of control of the promised goods and when the Company receives payment is based on a general 60-day payment term.
Description of sales return	Distributors can request to return product to the Company only due to quality issues or for product purchased within one year prior to the product’s expiration date
Accumulated deficit	$ (974,011,000)		(784,720,000)
Accumulated other comprehensive loss	(4,499,000)		(747,000)
ASU 2018-02 [Member] \| Impact of change in accounting principle upon adoption of ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated deficit				$ 600,000
Accumulated other comprehensive loss				(600,000)
ASU 2016-01 [Member] \| Impact of change in accounting principle upon adoption of ASU 2016-01 [Member]
Accounting Policy [Line Items]
Accumulated deficit					$ (1,300,000)
Accumulated other comprehensive loss					$ 1,300,000
Cumulative Effect, Period of Adoption, Adjustment [Member] \| ASU 2016-02 [Member]
Accounting Policy [Line Items]
Accumulated deficit				$ (8,700,000)
Europe [Member] \| Astellas Agreement [Member]
Accounting Policy [Line Items]
Amount constrained related to drug product shipment	$ 6,000,000.0
Minimum [Member] \| Computer Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	3 years
Minimum [Member] \| Laboratory Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	3 years
Minimum [Member] \| Machinery [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	3 years
Minimum [Member] \| Furniture and Fixtures [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	3 years
Maximum [Member] \| Computer Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	5 years
Maximum [Member] \| Laboratory Equipment [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	5 years
Maximum [Member] \| Machinery [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	5 years
Maximum [Member] \| Furniture and Fixtures [Member]
Accounting Policy [Line Items]
Property and equipment estimated useful life	5 years
Foreign subsidiaries [Member]
Accounting Policy [Line Items]
Cash and cash equivalents	$ 66,000,000.0		$ 11,900,000
Accounts Receivable from Distributors [Member] \| Credit Concentration Risk [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	64.00%

Summary of Significant Accounting Policies - Schedule of Significant Balance of Accounts Receivable (Detail) - Accounts Receivable [Member] - Credit Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Astellas Agreement [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	10.00%	17.00%
AstraZeneca Agreements [Member]
Accounting Policy [Line Items]
Concentration risk, percentage	26.00%	81.00%

Acquisition and Variable Interest Entity - Additional Information (Detail) $ in Thousands, ¥ in Millions			1 Months Ended		12 Months Ended
	Sep. 15, 2020 USD ($)	Sep. 15, 2020 CNY (¥)	Jul. 31, 2020 USD ($)	Jul. 31, 2020 CNY (¥)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 CNY (¥)
Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares owned					51.10%	51.10%
Investment \| $					$ 2,825
Beijing Falikang Pharmaceutical Co. Ltd [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Acquisition And Variable Interest Entity [Line Items]
Investment					2,800	¥ 19.2
FibroGen Beijing [Member] \| Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares acquired						48.90%
Cash consideration					$ 1,400	¥ 8.9
Percentage of outstanding shares owned					51.10%	51.10%
Falikang's total registered capital \| ¥						¥ 17.5
Beijing Kangda Yongfu Pharmaceutical Co., LTD [Member] \| FibroGen Beijing [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares acquired				100.00%
Cash consideration			$ 2,100	¥ 15.0
Transaction costs \| ¥				5.0
Acquisition costs			400	¥ 2.5
Beijing Kangda Yongfu Pharmaceutical Co., LTD [Member] \| FibroGen Beijing [Member] \| Acquired License [Member]
Acquisition And Variable Interest Entity [Line Items]
Entire purchase price \| $			$ 2,500
Beijing Kangda Yongfu Pharmaceutical Co., LTD [Member] \| FibroGen Beijing [Member] \| AstraZeneca AB [Member] \| Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares sold in exchange for cash consideration	48.90%	48.90%
Cash consideration for exchange of outstanding shares	$ 1,000	¥ 7.3
Percentage of outstanding shares owned	51.10%	51.10%

Acquisition and Variable Interest Entity - Summary of Equity Method Investment (Detail) - Beijing Falikang Pharmaceutical Co. Ltd [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Acquisition And Variable Interest Entity [Line Items]
Ownership Percentage	51.10%
Beginning balance	$ 0
Additions	2,825
Share of Net Loss	(202)
Currency Translation	105
Ending balance	$ 2,728

Collaboration Agreements and Revenues - Astellas Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended		12 Months Ended			35 Months Ended	45 Months Ended
	Dec. 31, 2020	Sep. 30, 2019	Apr. 30, 2006	Jun. 30, 2005	Jun. 30, 2020	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2009	Feb. 28, 2009	Jun. 30, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue							$ 176,319	$ 256,577	$ 212,958
Unbilled contract asset	$ 2,147						2,147	180,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue							$ 8,906	(36,324)	64,776
Japan [Member] \| Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue					$ 8,200				64,800
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset					130,000
Astellas Agreement [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received											$ 40,100
Potential milestone payments	15,000	$ 12,500		$ 132,500
Commercial sales milestone				15,000
Additional consideration based on net sales description							the low 20% range of the list price
Aggregate considerations received excluding drug product revenue	105,100						$ 105,100
Transaction price and allocated to performance obligations	15,000	$ 12,500					15,000
Consideration associated with milestone included in transaction price						$ 15,000
Astellas Agreement [Member] \| Japan [Member] \| Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue							$ 4,300	(36,300)	$ 64,800
Astellas Agreement [Member] \| Japan [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments				22,500
Astellas Agreement [Member] \| Japan [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments				$ 95,000
Astellas Agreement [Member] \| Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received										$ 320,000
Additional consideration based on net sales description							low 20% range
Aggregate considerations received excluding drug product revenue	540,000						$ 540,000
Transaction price and allocated to performance obligations												$ 130,000
Development and regulatory approval milestones			$ 425,000
Percentage of joint development costs committed to fund			50.00%
Revenue during period from performance obligations	$ 800						$ 800	128,800
Unbilled contract asset								$ 130,000
Milestone payment received					$ 130,000
Estimated joint development extended service period							2024
Astellas Agreement [Member] \| Europe [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 90,000
Astellas Agreement [Member] \| Europe [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 335,000

Collaboration Agreements and Revenues - AstraZeneca Agreements - Additional Information 1 (Detail) - USD ($)				3 Months Ended	12 Months Ended
	Dec. 29, 2018	Dec. 17, 2018	Jul. 30, 2013	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2015	Jun. 30, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset				$ 2,147,000	$ 2,147,000	$ 180,000,000
Drug product revenue					176,319,000	256,577,000	$ 212,958,000
Accrued long-term co-promotion expenses				27,424,000	27,424,000	53,071,000
Accrued long term co promotion liability current				11,500,000	11,500,000
Deferred revenue ($2,907 and $249 to a related party)				6,547,000	6,547,000	490,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue					8,906,000	(36,324,000)	64,776,000
AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price and allocated to performance obligations									$ 50,000,000.0
Revenue during period from performance obligations				600,000	$ 600,000	42,400,000
Unbilled contract asset						50,000,000.0
Estimated joint development extended service period					2024
Historical co-promotion costs					$ 0
AstraZeneca Agreements [Member] \| Selling, General and Administrative Expenses [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reversal of accrued co-promotion expenses				84,400,000
Co-promotion expenses					27,200,000
AstraZeneca Agreements [Member] \| Other Noncurrent Liabilities
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accrued long-term co-promotion expenses				27,400,000	27,400,000
AstraZeneca Agreements [Member] \| Accounts Payable [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accrued long term co promotion liability current				16,900,000	16,900,000
AstraZeneca Agreements [Member] \| Accrued Liabilities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accrued long term co promotion liability current				11,500	11,500
AstraZeneca Agreements [Member] \| Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue					4,625,000	0	0
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments			$ 374,000,000.0
Potential milestone payments			875,000,000.0
Commercial sales milestone			325,000,000.0
Aggregate considerations received excluding drug product revenue				439,000,000.0	$ 439,000,000.0
Shared development costs								$ 233,000,000.0
Additional consideration based on net sales description					low 20% range
Unbilled contract asset						50,000,000.0
Drug product revenue					$ 4,600
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| FibroGen, Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shared development costs								$ 116,500,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			65,000,000.0
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			325,000,000.0
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Deferred Approval Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			160,000,000.0
AstraZeneca Agreements [Member] \| China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			348,500,000		22,000,000.0
Drug product revenue					(90,000)	90,000	0
Proceeds from upfront, non-contingent and non-refundable payments			28,200,000
Commercial sales and other events milestone			187,500,000
Aggregate considerations received				77,200,000	77,200,000
Milestone payment received						$ 18,700,000
Milestone payment, revenue recognition	$ 6,000,000.0	$ 6,000,000.0			12,000,000.0		$ 9,900,000
Deferred revenue ($2,907 and $249 to a related party)				7,000,000.0	7,000,000.0
AstraZeneca Agreements [Member] \| China [Member] \| Accrued and Other Current Liabilities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue ($2,907 and $249 to a related party)				$ 7,000,000.0	$ 7,000,000.0
AstraZeneca Agreements [Member] \| China [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			15,000,000.0
AstraZeneca Agreements [Member] \| China [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 146,000,000.0

Collaboration Agreements and Revenues - Accounting for the Astellas Agreements - Additional Information 2 (Detail) - Astellas Agreement [Member]	12 Months Ended
	Dec. 31, 2020 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Co-development services, currently estimated continuation year	2024
Minimum [Member] \| Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	17.5
Maximum [Member] \| Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	20.0
Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	$ 40,100,000
Variable consideration related to payments for milestones considered probable of being achieved	65,000,000.0
Variable consideration related to co-development billings	11,700,000
Provision for co-development services	0
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	320,000,000.0
Variable consideration related to payments for milestones considered probable of being achieved	220,000,000.0
Variable consideration related to co-development billings	$ 225,900,000

Collaboration Agreements and Revenues - Accounting for the AstraZeneca Agreements - Additional Information 3 (Detail) - AstraZeneca Agreements [Member] $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty rate against projected net revenues	40.00%
Co-development services, currently estimated continuation year	2024
Measurement Input Discount Rate [Member] \| Discounted Cash Flow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Discount rate applied	17.5
U.S./RoW and China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-contingent upfront payments received	$ 402.2
Variable consideration related to payments for milestones considered probable of being achieved	114.0
Variable consideration related to co-development billings	564.9
Variable consideration related to profit share	$ 7.0

Collaboration Agreements and Revenues - Summary of License Revenue and Development Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 176,319	$ 256,577	$ 212,958
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	14,323	177,086	22,269
Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	80,592	114,115	125,913
Astellas Agreement [Member] \| License Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	14,323	11,935	14,323
Astellas Agreement [Member] \| License Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	117,470	0
Astellas Agreement [Member] \| Development Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	1,220	1,222	2,400
Astellas Agreement [Member] \| Development Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	17,954	28,172	18,503
AstraZeneca Agreements [Member] \| China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	(90)	90	0
AstraZeneca Agreements [Member] \| License Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	47,681	7,946
AstraZeneca Agreements [Member] \| Development Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 61,508	$ 84,629	$ 104,970

Collaboration Agreements and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	$ 2,147	$ 54,790
Astellas Agreement [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	116,697
Deferred Revenue	130
Total Consideration	116,827
Astellas Agreement [Member] \| Japan [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	100,347
Deferred Revenue	0
Total Consideration	100,347
Astellas Agreement [Member] \| Japan [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	16,350
Deferred Revenue	130
Total Consideration	16,480
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	736,913
Deferred Revenue	1,429
Total Consideration	738,342
Astellas Agreement [Member] \| Europe [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	487,951
Deferred Revenue	0
Total Consideration	487,951
Astellas Agreement [Member] \| Europe [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	248,962
Deferred Revenue	1,429
Total Consideration	250,391
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	896,619
Deferred Revenue	139,614
Total Consideration	1,036,233
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	341,844
Deferred Revenue	0
Total Consideration	341,844
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| Co-development, information sharing & committee services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	554,775
Deferred Revenue	2,276
Total Consideration	557,051
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| China performance obligation [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	0
Deferred Revenue	137,338
Total Consideration	$ 137,338

Collaboration Agreements and Revenues - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($)
Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	$ 0
Japan [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	15,100,000
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	27,600,000
Europe [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	1,500,000
U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	37,900,000
U.S./RoW and China [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	$ (2,900,000)

Collaboration Agreements and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred revenue	$ 138,474	$ 99,449
Deferred revenue	2,147	54,790
Net unbilled co-development revenue	0	$ 125,210
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred revenue	137,500
Deferred revenue	139,600
Net unbilled co-development revenue	$ 2,100

Collaboration Agreements and Revenues - Summary of Product Revenue, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 176,319	$ 256,577	$ 212,958
Price Adjustment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	900
Non-key Account Hospital Listing Award [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	9,300
Contractual Sales Rebate [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	6,200	100
Product [Member]
Disaggregation Of Revenue [Line Items]
Gross revenue	89,027	2,803
Total revenue	72,498	1,700	$ 0
Product [Member] \| Price Adjustment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0	(936)
Product [Member] \| Non-key Account Hospital Listing Award [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(9,325)	0
Product [Member] \| Contractual Sales Rebate [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(6,189)	(149)
Product [Member] \| Other Discounts and Rebates [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(923)	(18)
Product [Member] \| Sales Return [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ (92)	$ 0

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Collaboration Agreements and Revenues - Product Revenue, Net - Additional Information 1 (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 176,319	$ 256,577	$ 212,958
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	72,498	1,700	$ 0
Reductions to gross accounts receivable	800	1,100
Non-key Account Hospital Listing Award [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	9,300
Non-key Account Hospital Listing Award [Member] \| Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	(9,325)	0
Contractual Sales Rebate [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	6,200	100
Contractual Sales Rebate [Member] \| Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	(6,189)	(149)
Price Adjustment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	900
Price Adjustment [Member] \| Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	0	(936)
Rebates and Discounts [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		0
Rebates and Discounts [Member] \| Gross Accounts Receivable [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	500	0
Rebates and Discounts [Member] \| Contract Liabilities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 15,100	$ 0

Collaboration Agreements and Revenues - Roll-forward of Related Contract Liabilities (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Contract with Customer Liability [Line Items]
Balance at December 31, 2019	$ (54,790)
Balance at December 31, 2020	(2,147)
Product [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2019	(1,102)
Additions	(16,497)
Deduction	2,184
Currency Translation and Other	(270)
Gross Contract Liabilities Balance	(15,685)
Balance Presented Net Against Accounts Receivable	548
Balance at December 31, 2020	(15,137)
Drug Product Revenue [Member] \| Astellas Agreement [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2019	0
Additions	(5,984)
Balance at December 31, 2020	$ (5,984)

Collaboration Agreements and Revenues - Drug Product Revenue - Summary of Drug Product Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue	$ 176,319	$ 256,577	$ 212,958
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue	8,906	(36,324)	64,776
Drug Product Revenue [Member] \| Astellas Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue	4,281	(36,324)	64,776
Drug Product Revenue [Member] \| AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue	$ 4,625	$ 0	$ 0

- Definition

+ References

+ Details

Collaboration Agreements and Revenues - Drug Product Revenue - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		$ 176,319,000	$ 256,577,000	$ 212,958,000
Deferred revenue ($2,907 and $249 to a related party)		6,547,000	490,000
Deferred revenue		138,474,000	99,449,000
U.S./RoW [Member] \| AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		4,600
Deferred revenue		137,500,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		8,906,000	(36,324,000)	64,776,000
Estimated variable consideration transaction price			36,300,000
Drug Product Revenue [Member] \| AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		4,625,000	0	0
Drug Product Revenue [Member] \| API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		4,000,000.0
Drug Product Revenue [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 8,200,000			64,800,000
Drug Product Revenue [Member] \| Japan [Member] \| Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		4,300,000	$ (36,300,000)	$ 64,800,000
Drug Product Revenue [Member] \| Europe [Member] \| Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue ($2,907 and $249 to a related party)		1,400,000
Deferred revenue		$ 4,600,000

Collaboration Agreements and Revenues - Deferred Revenue - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 2,147	$ 54,790
AstraZeneca Agreements [Member] \| China [Member]
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 3,500

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Transfers of assets from level 1 to 2	$ 0	$ 29,800,000	$ 0
Transfers of assets from level 2 to 1	0		0
Transfers of assets into level 3	0		0
Transfers of assets out of level 3	0		0
Transfers of liabilities from level 1 to 2	0	0	0
Transfers of liabilities from level 2 to 1	0	0	0
Transfers of liabilities into level 3	0	0	0
Transfers of liabilities out of level 3	$ 0	$ 0	$ 0

Fair Value Measurements - Fair Values of Financial Liabilities Carried at Historical Cost (Detail) - Lease obligations [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,141	$ 1,544
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,141	$ 1,544

Leases - Additional Information (Detail) - Lease	12 Months Ended
Leases - Additional Information (Detail) - Lease	Dec. 31, 2020	Dec. 31, 2013	Dec. 31, 2006
Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	3 years
Shorenstein Properties LLC [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term			15 years
Lessee, finance lease, expiration period			2023
Lessee, finance lease, option to extend the additional lease term			10 years
Lessee, finance lease, additional lease expiration period			2033
Percentage increases on each anniversary of rent commencement date			2.00%
Lessee, finance lease, existence of option to extend			true
Lessee, finance lease, option to extend	The Company has an option to extend the lease for an additional 10 years through 2033.
Beijing Economic-Technological Development Area [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term		8 years
Lessee, finance lease, expiration period		2021
Lessee, finance lease, existence of option to extend		false
Building [Member]
Lessee Lease Description [Line Items]
Number of finance leases	2
Office Spaces [Member]
Lessee Lease Description [Line Items]
Number of operating leases	6
Lessee, operating lease, expiration period	2023
Office Equipment [Member] \| Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Office Equipment [Member] \| Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	4 years

Leases - Schedule of Lease Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Right-of-use assets - cost	$ 50,477	$ 49,909
Accumulated amortization	(20,871)	(10,307)
Finance lease right-of-use assets, net	29,606	39,602
Right-of-use assets - cost	3,934	2,736
Accumulated amortization	(1,891)	(805)
Operating lease right-of-use assets, net	2,043	1,931
Total lease assets	31,649	41,533
Finance lease liabilities	12,330	12,351
Operating lease liabilities	$ 1,188	$ 983
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	fgen:AccruedAndOtherCurrentLiabilitiesMember	fgen:AccruedAndOtherCurrentLiabilitiesMember
Finance lease liabilities	$ 25,391	$ 37,610
Operating lease liabilities	$ 853	$ 942
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherNoncurrentLiabilitiesMember	us-gaap:OtherNoncurrentLiabilitiesMember
Total lease liabilities	$ 39,762	$ 51,886

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finance lease cost:
Amortization of right-of-use assets	$ 10,369	$ 10,307	$ 0
Interest on lease liabilities	1,932	2,373
Operating lease cost	1,151	891
Sublease income	(1,201)	(1,385)
Total lease cost	$ 12,251	$ 12,186

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 951	$ 914
Operating cash flows from finance leases	1,896	2,196
Financing cash flows from finance leases	12,620	11,925	$ 0
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases	662	49,909
Operating leases	$ 1,072	$ 2,736

Leases - Schedule of Lease Term and Discount Rate (Detail)	Dec. 31, 2020	Dec. 31, 2019
Weighted-average remaining lease term (years):
Finance leases	2 years 10 months 24 days	3 years 7 months 6 days
Operating leases	1 year 9 months 18 days	2 years 1 month 6 days
Weighted-average discount rate:
Finance leases	4.39%	4.42%
Operating leases	4.74%	4.75%

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
Finance Leases
2021	$ 13,689
2022	13,886
2023	12,526
Total future lease payments	40,101
Less: Interest	(2,380)
Present value of lease liabilities	37,721
Operating Leases
2021	1,142
2022	839
2023	143
Total future lease payments	2,124
Less: Interest	(83)
Present value of lease liabilities	$ 2,041

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Cash	$ 88,046	$ 40,715
Money market funds	590,347	85,551
Total cash and cash equivalents	$ 678,393	$ 126,266

Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,272	$ 467,850
Gross Unrealized Holding Gains	119	784
Gross Unrealized Holding Losses	(3)	(25)
Fair Value	8,388	468,609
U.S. treasury notes and bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		426,995
Gross Unrealized Holding Gains		536
Gross Unrealized Holding Losses		(25)
Fair Value		427,506
Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		30,000
Gross Unrealized Holding Gains		32
Gross Unrealized Holding Losses		0
Fair Value		30,032
Bond and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,147	10,730
Gross Unrealized Holding Gains	0	86
Gross Unrealized Holding Losses	(3)	0
Fair Value	8,144	10,816
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	125	125
Gross Unrealized Holding Gains	119	130
Gross Unrealized Holding Losses	0	0
Fair Value	$ 244	$ 255

Balance Sheet Components - Summary of Contractual Maturities of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Available For Sale Securities Debt Maturities [Abstract]
Within one year - Bond and mutual funds	$ 8,144
Equity investments	244
Total investments	$ 8,388	$ 468,609

Balance Sheet Components - Additional Information (Detail)	3 Months Ended	12 Months Ended			36 Months Ended
	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) Milestone	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporary impairment loss					$ 0
Percentage of pre-launch inventory capitalized of aggregate inventory balance		29.00%			29.00%
Number of regulatory milestones \| Milestone			2
Unbilled contract assets		$ 2,147,000	$ 180,000,000		$ 2,147,000
Depreciation expense		11,678,000	11,147,000	$ 6,562,000
API product price change in estimated variable consideration		0	36,324,000		0
Accrued long term co promotion liability current		11,500,000			11,500,000
Profit share liability		6,547,000	490,000		6,547,000
Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets						$ 130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets			130,000,000.0
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets			50,000,000.0
Accrued long-term co-promotional expenses			53,100,000
Reversal of previously accrued long-term co-promotion expenses	$ 84,400,000
AstraZeneca Agreements [Member] \| Other Noncurrent Liabilities
Schedule of Available-for-sale Securities [Line Items]
Accrued long-term co-promotional expenses		27,400,000			27,400,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets			$ 50,000,000.0
AstraZeneca Agreements [Member] \| China [Member]
Schedule of Available-for-sale Securities [Line Items]
Profit share liability		$ 7,000,000.0			$ 7,000,000.0

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Investments [Abstract]
Raw materials	$ 2,303	$ 325
Work-in-progress	8,114	2,264
Finished goods	6,113	4,298
Total inventories	$ 16,530	$ 6,887

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Current [Abstract]
Unbilled contract assets	$ 2,147	$ 180,000
Deferred revenues from associated contracts	(2,147)	(54,790)
Net unbilled contract assets	0	125,210
Prepaid assets	8,353	6,464
Other current assets	1,807	1,717
Total prepaid expenses and other current assets	$ 10,160	$ 133,391

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 144,894	$ 143,107
Less: accumulated depreciation	(111,247)	(100,364)
Property and equipment, net	33,647	42,743
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	102,006	101,548
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	18,143	17,329
Machinery [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,312	8,217
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,545	8,399
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,128	5,822
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 760	$ 1,792

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Preclinical and clinical trial accruals	$ 44,113	$ 16,279
API product price adjustment	0	36,324
Payroll and related accruals	22,800	19,784
Contract liabilities to pharmaceutical distributors	15,137	0
Accrued co-promotion expenses - current	11,537	0
Roxadustat profit share to AstraZeneca	7,007	0
Property taxes and other	5,970	2,044
Professional services	4,869	4,842
Other	8,088	4,543
Total accrued and other current liabilities	$ 119,521	$ 83,816

Balance Sheet Components - Schedule of Other Long-term Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Noncurrent [Abstract]
Accrued long-term co-promotion expenses	$ 27,424	$ 53,071
Other long-term tax liabilities	8,675	8,913
Operating lease liabilities, non-current	853	942
Other	2,690	2,481
Total other long-term liabilities	$ 39,642	$ 65,407

Product Development Obligations - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) DevelopmentObligation	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Number of product development obligations \| DevelopmentObligation	11
Accrued product development costs excluding interest	$ 11.6	$ 10.6
Accrued Interest	$ 7.1	$ 6.2
Bank of Finland Interest Rate [Member]
Debt Instrument [Line Items]
Percentage points deducted to reference rate to compute effective interest rate	1.00%
Minimum [Member]
Debt Instrument [Line Items]
Interest rate on product development advances	3.00%

Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Outstanding non-cancelable contract obligations	$ 86.0
Research and Pre-Clinical Stage Development Programs [Member]
Commitments And Contingencies [Line Items]
Maximum future milestone payments	$ 10.9

Commitments and Contingencies - Summary of Unconditional Purchase Obligations (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2021	$ 42,012
Purchase obligations due 2022	44,014
Total purchase obligations	86,026
Manufacture and Supply of Roxadustat [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2021	14,114
Purchase obligations due 2022	10,951
Total purchase obligations	25,065
Manufacture and Supply of Pamrevlumab [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2021	24,480
Purchase obligations due 2022	33,063
Total purchase obligations	57,543
Other Purchases [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations due 2021	3,418
Purchase obligations due 2022	0
Total purchase obligations	$ 3,418

Equity and Stock-based Compensation - Subsidiary Stock and Non-Controlling Interests - Additional information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Nov. 19, 2014
Class Of Stock [Line Items]
Preferred stock, shares outstanding	0	0
IPO [Member]
Class Of Stock [Line Items]
Conversion rights, shares issued upon conversion of each preferred share			958,996
FibroGen Europe [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	42,619,022	42,619,022
Preferred stock redemption percentage	Redemption Right — If a Preferred Share can be redeemed by a majority shareholder owning more than ninety percent (90%) of the shares of FibroGen Europe in accordance with the provisions of the Finnish Limited Liability Companies Act, the minority holders of Preferred Shares have the right to request redemption of their shares.
Minimum percentage of shareholder's approval to call for redemption of preferred shares	90.00%
Preferred stock, voting rights	one vote
Conversion rights, shares issued upon conversion of each preferred share	1
FibroGen Europe [Member] \| Series A [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,700,845	1,700,845
FibroGen Europe [Member] \| Series B [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,875,000	1,875,000
FibroGen Europe [Member] \| Series C [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,599,503	1,599,503
FibroGen Europe [Member] \| Series D [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	1,520,141	1,520,141
FibroGen Europe [Member] \| Series E [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	459,565	459,565
FibroGen Europe [Member] \| Series F [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	5,714,332	5,714,332
FibroGen Europe [Member] \| Series G [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	9,927,500	9,927,500
FibroGen Europe [Member] \| Series H [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	19,822,136	19,822,136
FibroGen Cayman [Member]
Class Of Stock [Line Items]
Conversion rights, shares issued upon conversion of each preferred share	1
FibroGen Cayman [Member] \| Series A [Member]
Class Of Stock [Line Items]
Preferred stock, shares outstanding	6,758,000	6,758,000
Preferred shares issued, price per share	$ 1.00
Cash dividend percentage	6.00%

Equity and Stock-based Compensation - Common Stock - Additional information (Detail)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Common stock voting rights	one vote

Equity and Stock-based Compensation - Summary of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Common stock outstanding	91,441	87,657
Stock options outstanding	9,290	10,018
RSUs outstanding	1,893	1,483
Shares reserved for future stock options and RSUs grant	7,910	7,725
Total shares of common stock reserved	114,604	110,220
ESPP [Member]
Class Of Stock [Line Items]
Shares reserved for future ESPP offering	4,070	3,337

Equity and Stock-based Compensation - Stock Plans - Additional information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total intrinsic value of options exercised		$ 66,943
RSUs released and issued net of shares withheld for taxes		526,055
Weighted-average fair value of awards granted		$ 29.99	$ 54.74	$ 53.69
2005 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options		4 years
2005 Stock Plan \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period of stock options		10 years
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options		5 years
Expiration period of stock options		10 years
Termination date of equity incentive plan		Nov. 12, 2024
Option vesting term		Option vesting schedules are determined by the Company at the time of issuance and generally have a four year vesting schedule (25% vesting on the first anniversary of the vesting base date and quarterly thereafter over the next 3 years).
Number of common stock reserved for issuance		7,909,854
Common stock reserved for future issuance, Description		Shares reserved for issuance increases on January 1 of each year commencing on January 1, 2016 and ending on January 1, 2024 by the lesser of (i) the amount equal to 4% of the number of shares issued and outstanding on December 31 immediately prior to the date of increase or (ii) such lower number of shares as may be determined by the board of directors. As of December 31, 2020, the Company has reserved 7,909,854 shares of its common stock that remains unissued for issuance under the 2014 Plan.
Percentage of common stock reserved for future issuance	4.00%
Number of common stock repurchased		0	0
Total intrinsic value of options exercised		$ 89,600	$ 59,200	$ 97,500
2014 Equity Incentive Plan \| First Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of vesting rights		25.00%
2014 Equity Incentive Plan \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair value exercise price grant date		100.00%

Equity and Stock-based Compensation - Stock Plans - Summary of Stock Option Transactions (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Beginning Balance, Shares \| shares	10,018
Granted, Shares \| shares	2,692
Exercised, Shares \| shares	(3,113)
Expired, Shares \| shares	(73)
Forfeited, Shares \| shares	(234)
Outstanding, Ending Balance, Shares \| shares	9,290
Vested and expected to vest, Shares \| shares	8,929
Exercisable, Shares \| shares	5,576
Outstanding, Beginning Balance, Weighted Average Exercise per Share \| $ / shares	$ 26.63
Granted, Weighted Average Exercise per Share \| $ / shares	31.55
Exercised, Weighted Average Exercise per Share \| $ / shares	10.73
Expired, Weighted Average Exercise per Share \| $ / shares	39.92
Forfeited, Weighted Average Exercise per Share \| $ / shares	40.11
Outstanding, Ending Balance, Weighted Average Exercise per Share \| $ / shares	32.94
Vested and expected to vest, Weighted Average Exercise per Share \| $ / shares	32.76
Exercisable, Weighted Average Exercise per Share \| $ / shares	$ 29.50
Outstanding, Weighted Average Remaining Contractual Life	6 years 7 months 6 days
Vested and expected to vest, Weighted Average Remaining Contractual Life	6 years 6 months
Exercisable, Weighted Average Remaining Contractual Life	5 years 1 month 6 days
Outstanding, Aggregate Intrinsic Value \| $	$ 86,013
Vested and expected to vest, Aggregate Intrinsic Value \| $	84,125
Exercisable, Aggregate Intrinsic Value \| $	$ 66,943

Equity and Stock-based Compensation - Summary of RSU Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested, Shares, Beginning Balance	1,483
Unvested, Shares, Ending Balance	1,893	1,483
Granted, Fair value at Grant	$ 29.99	$ 54.74	$ 53.69
Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested, Shares, Beginning Balance	1,483
Granted, Shares	1,354
Vested, Shares	(813)
Forfeited, Shares	(131)
Unvested, Shares, Ending Balance	1,893	1,483
Unvested, Fair value at Grant, Beginning Balance	$ 49.05
Granted, Fair value at Grant	29.99
Vested, Fair value at Grant	45.55
Forfeited, Fair value at Grant	39.25
Unvested, Fair value at Grant, Ending Balance	$ 37.60	$ 49.05

Equity and Stock-based Compensation - Employee Stock Purchase Plan - Additional information (Detail) - 2014 ESPP [Member] - shares	1 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of common stock shares at discount	15.00%
Percentage of fair value exercise price grant date	85.00%
Number of common stock reserved for issuance	1,600,000
Common stock reserved for future issuance, Description		The Company has reserved 1,600,000 shares of its common stock for issuance under the 2014 ESPP and shares reserved for issuance increases January 1 of each year commencing January 1, 2016 by the lesser of (i) a number of shares equal to 1% of the total number of outstanding shares of common stock on December 31 immediately prior to the date of increase; (ii) 1,200,000 shares or (iii) such number of shares as may be determined by the board of directors.
Percentage of common stock reserved for future issuance	1.00%
Increase in number of shares of common stock reserved for future issuance, shares	1,200,000
Shares purchased by employees		143,876	135,115	230,317

Equity and Stock-based Compensation - Schedule of Recorded Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 72,720	$ 66,267	$ 52,142
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	46,229	41,015	30,491
Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 26,491	$ 25,252	$ 21,651

Equity and Stock-based Compensation - Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Employee Stock Purchase Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 8 months 12 days	5 years 3 months 18 days	5 years 4 months 24 days
Expected volatility	67.10%	68.00%	67.90%
Risk-free interest rate	0.80%	2.40%	2.70%
Expected dividend yield	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 18.36	$ 31.98	$ 32.12
Employee stock purchase plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	47.50%	48.10%	47.30%
Expected volatility, maximum	77.10%	62.10%	75.30%
Risk-free interest rate, minimum	0.10%	1.30%	0.80%
Risk-free interest rate, maximum	2.90%	2.90%	2.90%
Expected dividend yield	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 17.53	$ 19.27	$ 16.27
Employee stock purchase plans [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
Employee stock purchase plans [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years	2 years	2 years

Equity and Stock-based Compensation - Stock-Based Compensation - Additional information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Stock Option Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs	$ 63.9
Non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period	2 years 7 months 2 days
Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested stock option awards granted that will be recognized on a straight-line basis over the weighted-average period	2 years 8 months 23 days
Unrecognized compensation costs	$ 55.5

Equity and Stock-based Compensation - Warrants - Additional information (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020
Shareholders Equity And Stock Based Compensation [Abstract]
Warrants to purchase common stock exercised	4,430
Warrants to purchase common stock outstanding	0	0

Net Loss Per Share - Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	7,564	9,050	8,834
Employee stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	6,694	7,602	7,815
RSUs [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	564	1,187	820
ESPP [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	306	260	195
Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	0	1	4

FibroGen, Inc. 401(k) Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Defined contribution plan, maximum annual contributions per employee, percent	60.00%
Defined contribution plan, employer matching contributions	$ 3.2	$ 3.0	$ 2.9

Income Taxes - Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components Of Income Tax Expense Benefit Continuing Operations [Abstract]
Domestic	$ (195,617)	$ 2,538	$ (38,472)
Foreign	6,686	(79,180)	(47,644)
Loss before income taxes	$ (188,931)	$ (76,642)	$ (86,116)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68072869&loc=d3e41242-110953

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(8))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Income Taxes - Schedule of Components of Provision For Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0	$ 0	$ 0
State	0	0	2
Foreign	360	328	302
Total current	360	328	304
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred	0	0	0
Total provision for income taxes	$ 360	$ 328	$ 304

Income Taxes - Schedule of Reconciliation Between Statutory Federal Income Tax Rate and Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Tax at statutory federal rate	21.00%	21.00%	21.00%
State tax	0.00%	0.00%	0.00%
Stock-based compensation expense	2.40%	6.30%	14.50%
Benefit due to intercompany transfer of assets	41.70%	0.00%	0.00%
Valuation allowance on intercompany transfer of assets	(41.70%)	0.00%	0.00%
Net operating losses not benefitted	(23.20%)	(2.90%)	(23.20%)
Foreign net operating losses not benefitted	0.70%	(21.70%)	(11.60%)
Deduction limitation on executive compensation	(0.80%)	(2.50%)	(0.50%)
Other	(0.30%)	(0.60%)	(0.60%)
Total	(0.20%)	(0.40%)	(0.40%)

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Components Of Deferred Tax Assets And Liabilities [Abstract]
Federal and state net operating loss carryforwards	$ 134,033	$ 91,267
Tax credit carryforwards	62,465	52,243
Foreign net operating loss carryforwards	32,417	37,786
Stock-based compensation	10,399	11,159
Lease obligations	8,243	10,698
Reserves and accruals	5,875	5,353
Deferred revenue	13,550	13,323
Intangible assets	75,915	0
Other	0	284
Subtotal	342,897	222,113
Less: Valuation allowance	(337,824)	(213,847)
Net deferred tax assets	5,073	8,266
Fixed assets	(5,073)	(8,266)
Other	0	0
Net deferred tax liabilities	(5,073)	(8,266)
Total net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Increase in valuation allowance	$ 124,000,000.0	$ 19,900,000	$ 34,400,000
Deferred tax asset for temporary difference	78,700,000
Federal and state net operating loss carryforwards	134,033,000	91,267,000
Foreign net operating loss carryforwards	$ 32,417,000	$ 37,786,000
Percentage of ownership changes	0.00%
Unrecognized tax benefits	$ 48,600,000
Accrued interest, unrecognized tax benefits	0		$ 0
Unrecognized tax benefits that would affect effective tax rate	$ 500,000
Unrecognized tax benefits description	The Company does not anticipate a material change to its unrecognized tax benefits over the next twelve months that would affect the Company’s effective tax rate.
Earliest Tax Year [Member]
Income Taxes [Line Items]
Foreign statute of limitation generally remains open in the year	2011
Latest Tax Year [Member]
Income Taxes [Line Items]
Foreign statute of limitation generally remains open in the year	2020
Foreign net operating loss [Member]
Income Taxes [Line Items]
Foreign net operating loss carryforwards	$ 172,900,000
Foreign net operating loss [Member] \| Minimum [Member]
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2021
Foreign net operating loss [Member] \| Maximum [Member]
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2030
Federal [Member]
Income Taxes [Line Items]
Federal and state net operating loss carryforwards	$ 606,800,000
Operating loss carryforwards expiration year	2026
Other tax credit carryforwards	$ 66,900,000
Other tax credit carryforwards expiration year	2021
State [Member]
Income Taxes [Line Items]
Federal and state net operating loss carryforwards	$ 133,600,000
Operating loss carryforwards expiration year	2021
State [Member] \| California [Member]
Income Taxes [Line Items]
Other tax credit carryforwards	$ 32,900,000

Income Taxes - Reconciliation of the Beginning and Ending Amounts of Unrecognized Income Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Ending Balance	$ 48,600
Federal and State [Member]
Income Tax Contingency [Line Items]
Beginning balance	32,263	$ 27,956	$ 23,361
Increase due to prior positions			379
Decrease due to prior positions	(137)	(111)
Increase due to current year position	16,448	4,418	4,216
Ending Balance	$ 48,574	$ 32,263	$ 27,956

Related Party Transactions - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020
Related Party Transaction [Line Items]
Accounts receivable from related party		$ 4,127,000	$ 4,845,000
Deferred revenue		2,147,000	54,790,000
Unbilled contract asset		2,147,000	180,000,000
Net unbilled contract asset		0	125,210,000
Accrued liabilities and accounts payable to related party		24,000	36,883,000
Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset					$ 130,000,000.0
Astellas [Member]
Related Party Transaction [Line Items]
Drug product revenue from a related party		4,300,000	(36,300,000)	$ 64,800,000
Accrued liabilities and accounts payable to related party		1,100,000	36,900,000
Astellas [Member] \| Japan [Member]
Related Party Transaction [Line Items]
Drug product revenue from a related party		8,200,000
Astellas [Member] \| Europe [Member]
Related Party Transaction [Line Items]
Deferred revenue			4,800,000
Unbilled contract asset			130,000,000.0
Net unbilled contract asset		0	125,200,000
Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Expense related to collaboration agreements		500,000	2,800,000	1,500,000
Accounts receivable from related party		4,100,000	4,800,000
Deferred revenue		7,500,000	400,000
Falikang [Member]
Related Party Transaction [Line Items]
Investment	$ 2,800,000
Percentage of outstanding shares owned	51.10%
Equity method investments		2,700,000
Miscellaneous receivables		900,000
API Shipment [Member]
Related Party Transaction [Line Items]
License and development revenue related to collaboration agreements			36,300,000
API Shipment [Member] \| Astellas [Member] \| Japan [Member]
Related Party Transaction [Line Items]
License and development revenue related to collaboration agreements		(4,000,000.0)	(36,300,000)	64,800,000
License and Development [Member] \| Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
License and development revenue related to collaboration agreements		33,500,000	158,800,000	$ 35,200,000
Product [Member]
Related Party Transaction [Line Items]
Deferred revenue		$ 15,137,000	$ 1,102,000

Segment and Geographic Information - Additional information (Detail)	12 Months Ended
	Dec. 31, 2020 Segment
Number of operating segment	1
Customer Concentration Risk [Member] \| Percentage of Revenue [Member]
Concentration risk, percentage	42.00%
Customer Concentration Risk [Member] \| Percentage of Accounts Receivable [Member]
Concentration risk, percentage	64.00%

Segment and Geographic Information - Schedule of Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenue recognized	$ 176,319	$ 256,577	$ 212,958
Europe [Member]
Segment Reporting Information [Line Items]
Revenue recognized	67,161	132,400	112,916
Japan [Member]
Segment Reporting Information [Line Items]
Revenue recognized	36,660	122,475	100,002
China [Member]
Segment Reporting Information [Line Items]
Revenue recognized	72,498	1,700	0
All other [Member]
Segment Reporting Information [Line Items]
Revenue recognized	$ 0	$ 2	$ 40

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

Segment and Geographic Information - Schedule of Inventory by Geographic Area (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total inventory	$ 16,530	$ 6,887
United States [Member]
Segment Reporting Information [Line Items]
Total inventory	4,715	0
China [Member]
Segment Reporting Information [Line Items]
Total inventory	$ 11,815	$ 6,887

Segment and Geographic Information - Schedule of Long Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 33,647	$ 42,743
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	20,673	27,325
China [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 12,974	$ 15,418

Segment and Geographic Information - Summary of Finance and Operating Lease Right of Use Assets by Geographical Location (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Total finance lease right-of-use assets	$ 29,606	$ 39,602
Total operating lease right-of-use assets	2,043	1,931
United States [Member]
Total finance lease right-of-use assets	29,551	39,237
Total operating lease right-of-use assets	47	75
China [Member]
Total finance lease right-of-use assets	55	365
Total operating lease right-of-use assets	$ 1,996	$ 1,856

Segment and Geographic Information - Schedule of Customer Concentration by Collaboration Partners (Detail) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Percentage of Revenue [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	42.00%
Percentage of Revenue [Member] \| Astellas-Related party [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	21.00%	48.00%	47.00%
Percentage of Revenue [Member] \| AstraZeneca [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	37.00%	52.00%	53.00%
Percentage of Accounts Receivable [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	64.00%
Percentage of Accounts Receivable [Member] \| Astellas-Related party [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	10.00%	17.00%
Percentage of Accounts Receivable [Member] \| AstraZeneca [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk, percentage	26.00%	81.00%

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowances for Deferred Tax Assets [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 213,847	$ 193,987	$ 159,540
Charged (Credited) to Statement of Operation	123,977	19,860	34,447
Charged to Other Accounts - Liabilities and Equity	0	0	0
Deductions, Net	0	0	0
Balance at End of Year	337,824	213,847	193,987
Valuation Allowance for Rebates and Discounts [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	1,102	0
Charged (Credited) to Statement of Operation	16,497	1,102
Charged to Other Accounts - Liabilities and Equity	(14,867)	0
Deductions, Net	(2,184)	0
Balance at End of Year	$ 548	$ 1,102	$ 0