FibroGen (FGEN) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN INC
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		86,221,978

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 81,673	$ 89,258
Short-term investments	483,726	532,144
Accounts receivable ($3,898 and $47,210 from a related party)	6,023	63,684
Prepaid expenses and other current assets	7,578	4,929
Total current assets	579,000	690,015
Restricted time deposits	4,145	4,145
Long-term investments	132,203	55,820
Property and equipment, net	45,828	127,198
Finance lease right-of-use assets	47,029	0
Other assets	4,192	3,420
Total assets	812,397	880,598
Current liabilities:
Accounts payable	3,772	9,139
Accrued and other current liabilities ($519 and $444 to a related party)	66,278	66,123
Deferred revenue	12,104	13,771
Finance lease liabilities, current	11,766	0
Total current liabilities	93,920	89,033
Long-term portion of lease obligations	1,443	97,157
Product development obligations	16,545	16,798
Deferred rent	0	3,038
Deferred revenue, net of current	135,196	136,109
Finance lease liabilities, non-current	46,818	0
Other long-term liabilities	9,981	9,993
Total liabilities	303,903	352,128
Commitments and Contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at March 31, 2019 and December 31, 2018	0	0
Common stock, $0.01 par value; 225,000 shares authorized at March 31, 2019 and December 31, 2018; 86,130 and 85,432 shares issued and outstanding at March 31, 2019 and December 31, 2018	861	854
Additional paid-in capital	1,242,460	1,226,453
Accumulated other comprehensive loss	(937)	(2,281)
Accumulated deficit	(753,161)	(715,827)
Total stockholders’ equity	489,223	509,199
Non-controlling interests	19,271	19,271
Total equity	508,494	528,470
Total liabilities, stockholders’ equity and non-controlling interests	$ 812,397	$ 880,598

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Accounts receivable from related party	$ 3,898	$ 47,210
Accrued and other current liabilities to related party	$ 519	$ 444
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	86,130,000	85,432,000
Common stock, shares outstanding	86,130,000	85,432,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue:
Total revenue	$ 23,863	$ 31,925
Operating expenses:
Research and development	50,496	56,974
Selling, general and administrative	22,210	15,550
Total operating expenses	72,706	72,524
Loss from operations	(48,843)	(40,599)
Interest and other, net
Interest expense	(770)	(2,769)
Interest income and other, net	4,177	2,071
Total interest and other, net	3,407	(698)
Loss before income taxes	(45,436)	(41,297)
Provision for (benefit from) income taxes	(25)	99
Net loss	$ (45,411)	$ (41,396)
Net loss per share - basic and diluted	$ (0.53)	$ (0.50)
Weighted average number of common shares used to calculate net loss per share - basic and diluted	85,704	82,863
License Revenue [Member]
Revenue:
Total revenue	$ 0	$ 0
Development and Other Revenue [Member]
Revenue:
Total revenue	$ 23,863	$ 31,925

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Astellas Agreement [Member]
Collaboration services and other revenue from a related party	$ 4,859	$ 5,172

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (45,411)	$ (41,396)
Other comprehensive income (loss):
Foreign currency translation adjustments	291	(527)
Available-for-sale investments:
Unrealized gain (loss) on investments, net of tax effect	442	(50)
Net change in unrealized gain on available-for-sale investments	442	(50)
Other comprehensive income (loss), net of taxes	733	(577)
Comprehensive loss	$ (44,678)	$ (41,973)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2017	$ 547,738	$ 825	$ 1,160,094	$ (1,795)	$ (630,657)	$ 19,271
Balance, Shares at Dec. 31, 2017		82,498,128
Impact of change in accounting principle upon adoption | ASU 2016-01 [Member]	0	$ 0	0	(1,250)	1,250	0
Net loss	(41,396)	0	0	0	(41,396)	0
Change in unrealized gain or loss on investments	(50)	0	0	(50)	0	0
Foreign currency translation adjustments	(527)	0	0	(527)	0	0
Shares issued from stock plans, net of payroll taxes paid	2,146	$ 9	2,137	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		922,497
Stock-based compensation	10,878	$ 0	10,878	0	0	0
Balance at Mar. 31, 2018	518,789	$ 834	1,173,109	(3,622)	(670,803)	19,271
Balance, Shares at Mar. 31, 2018		83,420,625
Balance at Dec. 31, 2018	528,470	$ 854	1,226,453	(2,281)	(715,827)	19,271
Balance, Shares at Dec. 31, 2018		85,432,102
Impact of change in accounting principle upon adoption | ASU 2016-02 [Member]	8,688	$ 0	0	0	8,688	0
Impact of change in accounting principle upon adoption | ASU 2018-02 [Member]	0	0	0	611	(611)	0
Net loss	(45,411)	0	0	0	(45,411)	0
Change in unrealized gain or loss on investments	442	0	0	442	0	0
Foreign currency translation adjustments	291	0	0	291	0	0
Shares issued from stock plans, net of payroll taxes paid	(416)	$ 7	(423)	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		697,462
Stock-based compensation	16,430	$ 0	16,430	0	0	0
Balance at Mar. 31, 2019	$ 508,494	$ 861	$ 1,242,460	$ (937)	$ (753,161)	$ 19,271
Balance, Shares at Mar. 31, 2019		86,129,564

Condensed Consolidated Statem_5

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (45,411)	$ (41,396)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	2,744	1,519
Amortization of finance lease right-of-use assets	2,569	0
Net amortization of premium and discount on investments	(1,350)	277
Unrealized gain on cash equivalents and short-term equity investments	(51)	(165)
Gain on disposal of property and equipment	(10)	0
Stock-based compensation	16,430	10,878
Tax benefit on unrealized gain on available-for-sale securities	(118)	0
Changes in operating assets and liabilities:
Accounts receivable	57,661	(1,523)
Prepaid expenses and other current assets	(2,785)	1,380
Other assets	(51)	(364)
Accounts payable	(5,367)	(1,960)
Accrued and other liabilities	736	(1,066)
Deferred revenue	(2,580)	(5)
Lease obligations	0	14
Accrued interest for finance lease liabilities	219	0
Other long-term liabilities	(156)	448
Net cash provided by (used in) operating activities	22,480	(31,963)
Investing activities
Purchases of property and equipment	(483)	(1,837)
Purchases of available-for-sale securities and term deposit	(76,004)	(44)
Proceeds from maturities of investments	50,000	17,180
Net cash provided by (used in) investing activities	(26,487)	15,299
Financing activities
Repayments of finance lease liabilities	(3,017)	0
Repayments of lease obligations	(101)	(101)
Cash paid for payroll taxes on restricted stock unit releases	(5,988)	(6,813)
Proceeds from issuance of common stock	5,572	8,959
Net cash provided by (used in) financing activities	(3,534)	2,045
Effect of exchange rate change on cash and cash equivalents	(44)	(32)
Net decrease in cash and cash equivalents	(7,585)	(14,651)
Total cash and cash equivalents at beginning of period	89,258	673,658
Total cash and cash equivalents at end of period	$ 81,673	$ 659,007

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	1. Significant Accounting Policies Description of Operations FibroGen, Inc. (“FibroGen” or the “Company”) was incorporated in 1993 in Delaware and is a leading biopharmaceutical company discovering and developing a pipeline of first-in-class therapeutics. The Company has applied its pioneering expertise in hypoxia-inducible factor (“HIF”) and connective tissue growth factor (“CTGF”) biology to develop innovative medicines for the treatment of anemia, fibrotic disease, and cancer. Roxadustat (FG-4592), the Company’s most advanced product candidate, is an oral small molecule inhibitor of HIF prolyl hydroxylase (“HIF-PH”) activity. Roxadustat has received approval of its New Drug Application (“NDA”) in anemia associated with chronic kidney disease (“CKD”) in dialysis-dependent patients from the National Medical Products Administration (“NMPA”) of the People’s Republic of China (“China”). In conjunction with our collaboration partners, we have completed the Phase 3 trials of roxadustat intended to support B Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements include the accounts of FibroGen, its wholly owned subsidiaries and its majority-owned subsidiaries, FibroGen Europe Oy and FibroGen China Anemia Holdings, Ltd. (“FibroGen China”). All inter-company transactions and balances have been eliminated in consolidation. The Company operates in one segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs. The unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) applicable to interim financial reporting and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the United States Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and footnote disclosures normally included in the annual consolidated financial statements. The financial information included herein should be read in conjunction with the consolidated financial statements and related notes in the Company’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2018 (“2018 Form 10-K”). The accounting policies used by the Company in its presentation of interim financial results are consistent with those presented in Note 2 to the consolidated financial statements included in the 2018 Form 10-K, except for the following: Leases The Company determines if an arrangement is 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 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 will reassess the incremental borrowing rate periodically for application to any new leases or lease modifications or if any company-specific or general business conditions warrant. 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. 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, estimates of accruals related to clinical trial costs, valuation allowances for deferred tax assets, and valuation and recognition of stock-based compensation. 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. In the Company’s opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of its financial position, results of operations and cash flows for the interim periods presented. Recently Issued and Adopted Accounting Guidance ASC 842 In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) Leases (Topic 842): Targeted Improvements In addition, the Company elected the package of transitional practical expedients permitted under the transition guidance under ASC 842, which among other things allows the Company to carry forward its historical lease classification, and not to reassess initial direct costs for any existing leases. Meanwhile, the Company did not elect the hindsight practical expedient because it has limited number of leases, lease terms are straightforward, and most of its lease renewals are undefined until negotiated. In addition, the Company has elected the short term accounting policy practical expedient and does not apply the balance sheet recognition requirements for short-term leases (excluding expenses relating to leases with a lease term of one month or less), by class of underlying asset to which the right of use relates. The Company has not elected the non-lease components practical expedient, and therefore accounts for each lease component separately from the non-lease components. Upon adoption of ASC 842, the Company classified its existing building leases that were previously accounted for as build-to-suit arrangements as finance leases, and applied the transition guidance. Accordingly, the Company derecognized the assets and liabilities previously recognized under ASC 840 build-to-suit guidance. In addition, as a result of applying the transition guidance, the Company also recorded an adjustment to the accumulated depreciation of related leasehold improvements to reflect a change in estimated useful life from the building life to the shorter of the building life and remaining lease term. Differences between the assets and liabilities derecognized were recorded to the opening balance of retained earnings. The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands): Balance Sheet Line Item Nature of Adjustment New Lease Guidance Adoption Adjustment Assets Property and equipment, net Derecognition - build-to-suit lease assets - building shell, cost $ (53,880 ) Derecognition - build-to-suit lease assets - building shell, accumulated depreciation 13,476 Change of useful life - leasehold improvements, accumulated depreciation (38,877 ) Finance lease right-of-use assets Recognition - finance lease ROU assets 49,597 Other assets Recognition - operating lease ROU assets 730 Liabilities Accrued and other current liabilities Derecognition - deferred rent, current (619 ) Derecognition - build-to-suit lease liabilities, current (545 ) Recognition - operating lease liabilities, current 404 Finance lease liabilities, current Recognition - finance lease liabilities, current 11,499 Long-term portion of lease obligations Derecognition - build-to-suit lease liabilities, non-current (95,613 ) Deferred rent Derecognition - deferred rent, non-current (3,038 ) Finance lease liabilities, non-current Recognition - finance lease liabilities, non-current 49,884 Other long-term liabilities Recognition - operating lease liabilities, non-current 250 Stockholders’ equity Accumulated deficit Cumulative decrease to accumulated deficit $ 8,688 The adoption of this guidance did not have a material impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the three months ended March 31, 2019. ASU 2018-02 In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income Accumulated Other Comprehensive Loss Accumulated Deficit Balance at December 31, 2018 $ (2,281 ) $ (715,827 ) Impact of change in accounting principle upon adoption of ASU 2018-02 611 (611 ) Opening balance as of January 1, 2019 $ (1,670 ) $ (716,438 ) The adoption of this guidance had no impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the three months ended March 31, 2019. “Disclosure Update and Simplification,” ASU 2018-07 In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. Recently Issued Accounting Guidance Not Yet Adopted 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. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

Collaboration Agreements

Collaboration Agreements	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Agreements	2. Collaboration Agreements 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. 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). Under the Europe Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $425.0 million in potential milestone payments, 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. 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 AstraZeneca and Astellas. 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 end of 2023 to allow for development of this indication. 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, $15.0 million of which was received in 2015 as a result of the finalization of its two audited pre-clinical carcinogenicity study reports, (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. 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 paid upfront, non-contingent and non-refundable payments 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) 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. As mentioned above, 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 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 AstraZeneca and Astellas. In addition to CIA, in December 2018, anemia of chronic inflammation (“ACI”) and multiple myeloma (“MM”) have been 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, ACI and MM under the AstraZeneca agreements is estimated to continue through the end of 2024, to allow for development of these additional indications. On December 17, 2018, FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), received marketing authorization from the NMPA for roxadustat, a first-in-class hypoxia-inducible factor 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 . 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 condensed consolidated statements of operations. All other elements identified below are included in the “Development and other revenue” line item in the condensed consolidated statements of operations. Amounts recognized as revenue under the Japan Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 Japan License revenue $ — $ — Development revenue $ 246 $ 449 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 March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 74,089 $ — $ 74,089 Development revenue 14,154 207 14,361 Total license and development revenue $ 88,243 $ 207 $ 88,450 The revenue recognized under the Japan Agreement for the three months ended March 31, 2019 included an immaterial amount resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the Japan Agreement includes $0.9 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 revenue under the Europe Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 Europe License revenue $ — $ — Development revenue $ 4,613 $ 4,723 The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Europe Agreement, along with any associated deferred revenue as follows (in thousands): Europe Agreement Cumulative Revenue Through March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 370,481 $ — $ 370,481 Development revenue 207,450 2,334 209,784 Total license and development revenue $ 577,931 $ 2,334 $ 580,265 The revenue recognized under the Europe Agreement for the three months ended March 31, 2019 included an increase in revenue of $0.1 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the Europe Agreement includes $12.7 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 revenue under the U.S./RoW Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 U.S. / RoW and China License revenue $ — $ — Development revenue 19,004 26,723 China performance obligation $ — $ — 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 March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 294,163 $ — $ 294,163 Co-development, information sharing & committee services 427,641 16,787 444,428 China performance obligation — 127,972 127,972 Total license and development revenue $ 721,804 $ 144,759 $ 866,563 The revenue recognized under the U.S./RoW Agreement for the three months ended March 31, 2019 included an increase in revenue of $0.9 million resulting from changes to estimated variable consideration in the current period 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 $172.3 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period, except for amounts allocated to the China performance obligation, which are expected to be recognized in a pattern consistent with estimated deliveries of the commercial drug product. Other Revenues Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented. Deferred Revenue Deferred revenue represents amounts 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. The long term portion of deferred revenue also includes amounts allocated to the China unit of accounting under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China, which is not expected to occur within the next year.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands): March 31, 2019 Level 1 Level 2 Level 3 Total US treasury notes and bills $ 344,728 $ 150,368 $ — $ 495,096 Bond and mutual funds 10,591 — — 10,591 Equity investments 246 — — 246 Money market funds 9,395 — — 9,395 Term deposit — 80,000 — 80,000 Certificate of deposit — 29,996 — 29,996 Total $ 364,960 $ 260,364 $ — $ 625,324 December 31, 2018 Level 1 Level 2 Level 3 Total US treasury notes and bills $ 292,317 $ 224,953 $ — $ 517,270 Bond and mutual funds 10,484 — — 10,484 Equity investments 234 — — 234 Money market funds 541 — — 541 Term deposit — 80,000 — 80,000 Certificate of deposit — 29,910 — 29,910 Total $ 303,576 $ 334,863 $ — $ 638,439 Our 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. The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands): March 31, 2019 Level 1 Level 2 Level 3 Total Lease obligations $ — $ — $ 1,846 $ 1,846 December 31, 2018 Level 1 Level 2 Level 3 Total Lease obligations $ — $ — $ 98,105 $ 98,105 The fair values 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. As of December 31, 2018, the Company had $96.2 million in lease obligations related to its building leases under build-to-suit arrangements. Upon the adoption of ASC 842 as of January 1, 2019, using the modified retrospective transition method, the Company derecognized these liabilities previously recognized under ASC 840 build-to-suit designation. Refer to Note 1 for details. The remaining balance of $1.8 million as of March 31, 2019 under lease obligations is related to an expansion option in the Company’s long-term property lease with Shorenstein Properties LLC (“Alexandria” or “landlord”). This expansion option allowed the Company to occupy part of an adjacent building within 31 months of the lease commencement date in 2008. In 2012, the Company gave notice to its landlord that it would not exercise this expansion option, which resulted in a $5.0 million payment liability to the landlord that is financed over the remaining lease term to 2023. There were no transfers of assets or liabilities between levels for any of the periods presented.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	4. 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 (“BYBP”) 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 four additional real estate leases for space within a building, which are treated as operating leases. These leases have lease terms ranging from two to four years. 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 office equipment leases for printers and copiers, with contracted lease terms ranging from three to five years. These lease contracts provide for fixed monthly rent payments, and are scheduled to automatically renew for an additional term upon lease expiration, unless purchased or returned. The Company does not anticipate exercising the additional lease terms and instead plans to return the equipment upon lease expiration. Additionally, the Company has one lease of an automobile in Cangzhou, China, with initial lease term of two years. The lease contract provides for fixed monthly rent payments, with no option to renew the lease. The Company’s lease assets and related lease liabilities were as follows (in thousands): Balance Sheet Line Item March 31, 2019 Assets Finance: Right-of-use assets - cost $ 49,598 Accumulated amortization (2,569 ) Finance lease right-of-use assets, net Finance lease right-of-use assets 47,029 Operating: Right-of-use assets - cost 730 Accumulated amortization (122 ) Operating lease right-of-use assets, net Other assets 608 Total lease assets $ 47,637 Liabilities Current: Finance lease liabilities Finance lease liabilities, current $ 11,766 Operating lease liabilities Accrued and other current liabilities 436 Non-current: Finance lease liabilities Finance lease liabilities, non-current 46,818 Operating lease liabilities Other long-term liabilities 129 Total lease liabilities $ 59,149 The components of lease expense were as follows (in thousands): Statement of Operations Line Item Three Months Ended March 31, 2019 Finance lease cost: Amortization of right-of-use assets Selling, general and administrative expenses $ 2,569 Interest on lease liabilities Interest expense 640 Operating lease cost Research and development, Selling, general and administrative expenses 126 Sublease income Selling, general and administrative expenses (588 ) Total lease cost $ 2,747 Supplemental cash flow information related to leases were as follows (in thousands): Three Months Ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 99 Operating cash flows from finance leases 435 Financing cash flows from finance leases 3,017 Right-of-use assets obtained in exchange for new lease liabilities: Finance leases 49,597 Operating leases $ 730 Lease term and discount rate were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (years): Finance leases 4.3 Operating leases 1.2 Weighted-average discount rate: Finance leases 4.43 % Operating leases 4.74 % Maturities of lease liabilities are as follows: Year Ending Finance Leases Operating Leases 2019 (Remaining nine month period) $ 10,326 $ 326 2020 14,106 217 2021 13,679 25 2022 13,879 16 2023 12,523 — Total future lease payments 64,513 584 Less: Interest (5,929 ) (19 ) Present value of lease liabilities $ 58,584 $ 565 The following information was previously disclosed under ASC 840 as of December 31, 2018: Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands): Year Ending Operating Leases 2019 $ 444 2020 232 2021 25 2022 16 2023 — Total minimum payments $ 717 Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands): Year Ending Lease financing obligations 2019 $ 14,379 2020 14,664 2021 14,179 2022 14,335 2023 12,872 Total minimum payments $ 70,429

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components Cash and Cash Equivalents Cash and cash equivalents consisted of the following (in thousands): March 31, 2019 December 31, 2018 Cash $ 72,278 $ 38,783 US treasury notes and bills — 49,934 Money market funds 9,395 541 Total cash and cash equivalents $ 81,673 $ 89,258 At March 31, 2019 and December 31, 2018, a total of $31.5 million and $21.9 million, respectively, of the Company’s cash and cash equivalents were held outside of the U.S. in its foreign subsidiaries to be used primarily for its China operations. Investments The Company’s investments consist of available-for-sale debt investments, marketable equity investments, a term deposit and a certificate of deposit. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale investments by major investments type are summarized in the tables below (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value US treasury notes and bills $ 494,580 $ 516 $ — $ 495,096 Term deposit 80,000 — — 80,000 Certificates of deposit 30,000 — (4 ) 29,996 Bond and mutual funds 10,533 58 — 10,591 Equity investments 125 121 — 246 Total investments $ 615,238 $ 695 $ (4 ) $ 615,929 December 31, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value US treasury notes and bills $ 467,296 $ 109 $ (69 ) $ 467,336 Term deposit 80,000 — — 80,000 Certificates of deposit 30,000 — (90 ) 29,910 Bond and mutual funds 10,464 20 — 10,484 Equity investments 125 109 — 234 Total investments $ 587,885 $ 238 $ (159 ) $ 587,964 At March 31, 2019, all of the available-for-sale investments had contractual maturities within two years. 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 months ended March 31, 2019 and 2018, the Company did not recognize any other-than-temporary impairment loss. Property and Equipment Property and equipment consisted of the following (in thousands): March 31, 2019 December 31, 2018 Leasehold improvements $ 101,229 $ 101,200 Building shell — 53,880 Laboratory equipment 16,480 16,405 Machinery 8,396 8,382 Computer equipment 6,650 6,473 Furniture and fixtures 5,643 5,690 Construction in progress 607 367 Total property and equipment $ 139,005 $ 192,397 Less: accumulated depreciation (93,177 ) (65,199 ) Property and equipment, net $ 45,828 $ 127,198 As of December 31, 2018, the Company had $53.9 million building shell cost and $13.5 million accumulated depreciation related to its building leases under build-to-suit arrangements. Upon the adoption of ASC 842 as of January 1, 2019, using the modified retrospective transition method, the Company derecognized these assets previously recognized under ASC 840 build-to-suit designation. Up to December 31, 2018, the leasehold improvements related to these building leases were depreciated over the life of the building under ASC 840. Upon the adoption of ASC 842, these leasehold improvements should have a useful life based on the lease term. As a result, at the adoption date, the Company recorded a cumulative adjustment of $38.9 million to the accumulated depreciation for these leasehold improvements so that their net balance equals the undepreciated amount had the useful life of the leasehold improvements always been equal to the lease terms. Refer to Note 1 for details. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): March 31, 2019 December 31, 2018 Preclinical and clinical trial accruals $ 41,964 $ 35,413 Payroll and related accruals 12,368 21,430 Property taxes and other 2,969 1,095 Professional services 3,547 2,648 Other 5,430 5,537 Total accrued liabilities $ 66,278 $ 66,123

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	6. Stock-Based Compensation Stock-based compensation expense was allocated to research and development and general and administrative expense as follows (in thousands): Three Months Ended March 31, 2019 2018 Research and development $ 9,578 $ 6,370 Selling, general and administrative 6,852 4,508 Total stock-based compensation expense $ 16,430 $ 10,878 The assumptions used to estimate the fair value of stock options granted and purchases under the Company’s 2014 Employee Share Purchase Plan (“ESPP”) using the Black-Scholes option valuation model were as follows: Three Months Ended March 31, 2019 2018 Stock Options Expected term (in years) 5.3 5.4 Expected volatility 67.9 % 67.9 % Risk-free interest rate 2.6 % 2.7 % Expected dividend yield — — Weighted average estimated fair value $ 34.14 $ 32.18 ESPPs Expected term (in years) 0.5 - 2.0 0.5 - 2.0 Expected volatility 48.1 - 62.1 % 54.9 - 75.3 % Risk-free interest rate 1.3 - 2.9 % 0.8 - 1.6 % Expected dividend yield — — Weighted average estimated fair value $ 20.57 $ 10.93

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	7. Income Taxes The benefit for the three months ended March 31, 2019 was primarily due to the tax effect arising from other comprehensive income related to available-for-sale securities, partially offset by foreign taxes. The provision for income taxes for the three months ended March 31, 2018 was due to foreign taxes. Based upon the weight of available evidence, which includes its historical operating performance, reported cumulative net losses since inception and expected continuing net loss, the Company has established and continues to maintain a full valuation allowance against its deferred tax assets as it does not currently believe that realization of those assets is more likely than not.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	8. Related Party Transactions Astellas is an equity investor in the Company and considered a related party. The Company recorded revenue related to collaboration agreements with Astellas of $4.9 million and $5.2 million during the three months ended March 31, 2019 and 2018, respectively. The Company recorded expense related to collaboration agreements with Astellas of $0.5 million and $0.6 million during the three months ended March 31, 2019 and 2018, respectively. As of March 31, 2019 and December 31, 2018, accounts receivable from Astellas were $3.9 million and $47.2 million, respectively, and amounts due to Astellas were $0.5 million and $0.4 million, respectively. The accounts receivable from Astellas as of December 31, 2018 included $43.8 million related to the delivery of roxadustat API to Astellas during the fourth quarter of 2018, pursuant to an amendment to the Japan Agreement that will allow Astellas to manufacture roxadustat drug product for commercialization in Japan. This amount was received during the first quarter of 2019.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Description of Operations	Description of Operations FibroGen, Inc. (“FibroGen” or the “Company”) was incorporated in 1993 in Delaware and is a leading biopharmaceutical company discovering and developing a pipeline of first-in-class therapeutics. The Company has applied its pioneering expertise in hypoxia-inducible factor (“HIF”) and connective tissue growth factor (“CTGF”) biology to develop innovative medicines for the treatment of anemia, fibrotic disease, and cancer. Roxadustat (FG-4592), the Company’s most advanced product candidate, is an oral small molecule inhibitor of HIF prolyl hydroxylase (“HIF-PH”) activity. Roxadustat has received approval of its New Drug Application (“NDA”) in anemia associated with chronic kidney disease (“CKD”) in dialysis-dependent patients from the National Medical Products Administration (“NMPA”) of the People’s Republic of China (“China”). In conjunction with our collaboration partners, we have completed the Phase 3 trials of roxadustat intended to support B
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements include the accounts of FibroGen, its wholly owned subsidiaries and its majority-owned subsidiaries, FibroGen Europe Oy and FibroGen China Anemia Holdings, Ltd. (“FibroGen China”). All inter-company transactions and balances have been eliminated in consolidation. The Company operates in one segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs. The unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) applicable to interim financial reporting and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the United States Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and footnote disclosures normally included in the annual consolidated financial statements. The financial information included herein should be read in conjunction with the consolidated financial statements and related notes in the Company’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2018 (“2018 Form 10-K”). The accounting policies used by the Company in its presentation of interim financial results are consistent with those presented in Note 2 to the consolidated financial statements included in the 2018 Form 10-K, except for the following:
Leases	Leases The Company determines if an arrangement is 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 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 will reassess the incremental borrowing rate periodically for application to any new leases or lease modifications or if any company-specific or general business conditions warrant. 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.
Use of Estimates	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, estimates of accruals related to clinical trial costs, valuation allowances for deferred tax assets, and valuation and recognition of stock-based compensation. 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. In the Company’s opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of its financial position, results of operations and cash flows for the interim periods presented.
Recently Issued and Adopted Accounting Guidance	Recently Issued and Adopted Accounting Guidance ASC 842 In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) Leases (Topic 842): Targeted Improvements In addition, the Company elected the package of transitional practical expedients permitted under the transition guidance under ASC 842, which among other things allows the Company to carry forward its historical lease classification, and not to reassess initial direct costs for any existing leases. Meanwhile, the Company did not elect the hindsight practical expedient because it has limited number of leases, lease terms are straightforward, and most of its lease renewals are undefined until negotiated. In addition, the Company has elected the short term accounting policy practical expedient and does not apply the balance sheet recognition requirements for short-term leases (excluding expenses relating to leases with a lease term of one month or less), by class of underlying asset to which the right of use relates. The Company has not elected the non-lease components practical expedient, and therefore accounts for each lease component separately from the non-lease components. Upon adoption of ASC 842, the Company classified its existing building leases that were previously accounted for as build-to-suit arrangements as finance leases, and applied the transition guidance. Accordingly, the Company derecognized the assets and liabilities previously recognized under ASC 840 build-to-suit guidance. In addition, as a result of applying the transition guidance, the Company also recorded an adjustment to the accumulated depreciation of related leasehold improvements to reflect a change in estimated useful life from the building life to the shorter of the building life and remaining lease term. Differences between the assets and liabilities derecognized were recorded to the opening balance of retained earnings. The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands): Balance Sheet Line Item Nature of Adjustment New Lease Guidance Adoption Adjustment Assets Property and equipment, net Derecognition - build-to-suit lease assets - building shell, cost $ (53,880 ) Derecognition - build-to-suit lease assets - building shell, accumulated depreciation 13,476 Change of useful life - leasehold improvements, accumulated depreciation (38,877 ) Finance lease right-of-use assets Recognition - finance lease ROU assets 49,597 Other assets Recognition - operating lease ROU assets 730 Liabilities Accrued and other current liabilities Derecognition - deferred rent, current (619 ) Derecognition - build-to-suit lease liabilities, current (545 ) Recognition - operating lease liabilities, current 404 Finance lease liabilities, current Recognition - finance lease liabilities, current 11,499 Long-term portion of lease obligations Derecognition - build-to-suit lease liabilities, non-current (95,613 ) Deferred rent Derecognition - deferred rent, non-current (3,038 ) Finance lease liabilities, non-current Recognition - finance lease liabilities, non-current 49,884 Other long-term liabilities Recognition - operating lease liabilities, non-current 250 Stockholders’ equity Accumulated deficit Cumulative decrease to accumulated deficit $ 8,688 The adoption of this guidance did not have a material impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the three months ended March 31, 2019. ASU 2018-02 In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income Accumulated Other Comprehensive Loss Accumulated Deficit Balance at December 31, 2018 $ (2,281 ) $ (715,827 ) Impact of change in accounting principle upon adoption of ASU 2018-02 611 (611 ) Opening balance as of January 1, 2019 $ (1,670 ) $ (716,438 ) The adoption of this guidance had no impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the three months ended March 31, 2019. “Disclosure Update and Simplification,” ASU 2018-07 In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting.
Recently Issued Accounting Guidance Not Yet Adopted	Recently Issued Accounting Guidance Not Yet Adopted 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. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments
Collaboration Arrangements	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. 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). Under the Europe Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $425.0 million in potential milestone payments, 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. 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 AstraZeneca and Astellas. 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 end of 2023 to allow for development of this indication. 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, $15.0 million of which was received in 2015 as a result of the finalization of its two audited pre-clinical carcinogenicity study reports, (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. 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 paid upfront, non-contingent and non-refundable payments 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) 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. As mentioned above, 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 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 AstraZeneca and Astellas. In addition to CIA, in December 2018, anemia of chronic inflammation (“ACI”) and multiple myeloma (“MM”) have been 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, ACI and MM under the AstraZeneca agreements is estimated to continue through the end of 2024, to allow for development of these additional indications. On December 17, 2018, FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), received marketing authorization from the NMPA for roxadustat, a first-in-class hypoxia-inducible factor 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 .
Other Revenues	Other Revenues Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented.
Deferred Revenue	Deferred Revenue Deferred revenue represents amounts 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. The long term portion of deferred revenue also includes amounts allocated to the China unit of accounting under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China, which is not expected to occur within the next year.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
ASU 2016-02 [Member]
Schedule of Impacts Upon Adoption of New Guidance	The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands): Balance Sheet Line Item Nature of Adjustment New Lease Guidance Adoption Adjustment Assets Property and equipment, net Derecognition - build-to-suit lease assets - building shell, cost $ (53,880 ) Derecognition - build-to-suit lease assets - building shell, accumulated depreciation 13,476 Change of useful life - leasehold improvements, accumulated depreciation (38,877 ) Finance lease right-of-use assets Recognition - finance lease ROU assets 49,597 Other assets Recognition - operating lease ROU assets 730 Liabilities Accrued and other current liabilities Derecognition - deferred rent, current (619 ) Derecognition - build-to-suit lease liabilities, current (545 ) Recognition - operating lease liabilities, current 404 Finance lease liabilities, current Recognition - finance lease liabilities, current 11,499 Long-term portion of lease obligations Derecognition - build-to-suit lease liabilities, non-current (95,613 ) Deferred rent Derecognition - deferred rent, non-current (3,038 ) Finance lease liabilities, non-current Recognition - finance lease liabilities, non-current 49,884 Other long-term liabilities Recognition - operating lease liabilities, non-current 250 Stockholders’ equity Accumulated deficit Cumulative decrease to accumulated deficit $ 8,688
ASU 2018-02 [Member]
Schedule of Impacts Upon Adoption of New Guidance	The impacts, based on the aggregate portfolio approach, to the Company’s accumulated other comprehensive loss and accumulated deficit upon adoption of this guidance are as follows (in thousands): Accumulated Other Comprehensive Loss Accumulated Deficit Balance at December 31, 2018 $ (2,281 ) $ (715,827 ) Impact of change in accounting principle upon adoption of ASU 2018-02 611 (611 ) Opening balance as of January 1, 2019 $ (1,670 ) $ (716,438 )

Collaboration Agreements (Table

Collaboration Agreements (Tables)	3 Months Ended
	Mar. 31, 2019
Japan [Member]
Summary of Revenue Recognized under Agreement	Amounts recognized as revenue under the Japan Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 Japan License revenue $ — $ — Development revenue $ 246 $ 449
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue	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 March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 74,089 $ — $ 74,089 Development revenue 14,154 207 14,361 Total license and development revenue $ 88,243 $ 207 $ 88,450
Europe [Member]
Summary of Revenue Recognized under Agreement	Amounts recognized as revenue under the Europe Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 Europe License revenue $ — $ — Development revenue $ 4,613 $ 4,723
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue	The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Europe Agreement, along with any associated deferred revenue as follows (in thousands): Europe Agreement Cumulative Revenue Through March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 370,481 $ — $ 370,481 Development revenue 207,450 2,334 209,784 Total license and development revenue $ 577,931 $ 2,334 $ 580,265
U.S./RoW and China [Member]
Summary of Revenue Recognized under Agreement	Amounts recognized as revenue under the U.S./RoW Agreement were as follows (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2019 2018 U.S. / RoW and China License revenue $ — $ — Development revenue 19,004 26,723 China performance obligation $ — $ —
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue	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 March 31, 2019 Deferred Revenue at March 31, 2019 Total Consideration Through March 31, 2019 License $ 294,163 $ — $ 294,163 Co-development, information sharing & committee services 427,641 16,787 444,428 China performance obligation — 127,972 127,972 Total license and development revenue $ 721,804 $ 144,759 $ 866,563

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
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): March 31, 2019 Level 1 Level 2 Level 3 Total US treasury notes and bills $ 344,728 $ 150,368 $ — $ 495,096 Bond and mutual funds 10,591 — — 10,591 Equity investments 246 — — 246 Money market funds 9,395 — — 9,395 Term deposit — 80,000 — 80,000 Certificate of deposit — 29,996 — 29,996 Total $ 364,960 $ 260,364 $ — $ 625,324 December 31, 2018 Level 1 Level 2 Level 3 Total US treasury notes and bills $ 292,317 $ 224,953 $ — $ 517,270 Bond and mutual funds 10,484 — — 10,484 Equity investments 234 — — 234 Money market funds 541 — — 541 Term deposit — 80,000 — 80,000 Certificate of deposit — 29,910 — 29,910 Total $ 303,576 $ 334,863 $ — $ 638,439
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): March 31, 2019 Level 1 Level 2 Level 3 Total Lease obligations $ — $ — $ 1,846 $ 1,846 December 31, 2018 Level 1 Level 2 Level 3 Total Lease obligations $ — $ — $ 98,105 $ 98,105

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of Lease Assets and Related Lease Liabilities	The Company’s lease assets and related lease liabilities were as follows (in thousands): Balance Sheet Line Item March 31, 2019 Assets Finance: Right-of-use assets - cost $ 49,598 Accumulated amortization (2,569 ) Finance lease right-of-use assets, net Finance lease right-of-use assets 47,029 Operating: Right-of-use assets - cost 730 Accumulated amortization (122 ) Operating lease right-of-use assets, net Other assets 608 Total lease assets $ 47,637 Liabilities Current: Finance lease liabilities Finance lease liabilities, current $ 11,766 Operating lease liabilities Accrued and other current liabilities 436 Non-current: Finance lease liabilities Finance lease liabilities, non-current 46,818 Operating lease liabilities Other long-term liabilities 129 Total lease liabilities $ 59,149
Components of Lease Expense	The components of lease expense were as follows (in thousands): Statement of Operations Line Item Three Months Ended March 31, 2019 Finance lease cost: Amortization of right-of-use assets Selling, general and administrative expenses $ 2,569 Interest on lease liabilities Interest expense 640 Operating lease cost Research and development, Selling, general and administrative expenses 126 Sublease income Selling, general and administrative expenses (588 ) Total lease cost $ 2,747
Schedule of Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases were as follows (in thousands): Three Months Ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 99 Operating cash flows from finance leases 435 Financing cash flows from finance leases 3,017 Right-of-use assets obtained in exchange for new lease liabilities: Finance leases 49,597 Operating leases $ 730
Schedule of Lease Term and Discount Rate	Lease term and discount rate were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (years): Finance leases 4.3 Operating leases 1.2 Weighted-average discount rate: Finance leases 4.43 % Operating leases 4.74 %
Schedule of Maturities of Finance and Operating Leases Liabilities	Maturities of lease liabilities are as follows: Year Ending Finance Leases Operating Leases 2019 (Remaining nine month period) $ 10,326 $ 326 2020 14,106 217 2021 13,679 25 2022 13,879 16 2023 12,523 — Total future lease payments 64,513 584 Less: Interest (5,929 ) (19 ) Present value of lease liabilities $ 58,584 $ 565
Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations	Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands): Year Ending Operating Leases 2019 $ 444 2020 232 2021 25 2022 16 2023 — Total minimum payments $ 717
Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations	Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands): Year Ending Lease financing obligations 2019 $ 14,379 2020 14,664 2021 14,179 2022 14,335 2023 12,872 Total minimum payments $ 70,429

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents	Cash and cash equivalents consisted of the following (in thousands): March 31, 2019 December 31, 2018 Cash $ 72,278 $ 38,783 US treasury notes and bills — 49,934 Money market funds 9,395 541 Total cash and cash equivalents $ 81,673 $ 89,258
Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments	The Company’s investments consist of available-for-sale debt investments, marketable equity investments, a term deposit and a certificate of deposit. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale investments by major investments type are summarized in the tables below (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value US treasury notes and bills $ 494,580 $ 516 $ — $ 495,096 Term deposit 80,000 — — 80,000 Certificates of deposit 30,000 — (4 ) 29,996 Bond and mutual funds 10,533 58 — 10,591 Equity investments 125 121 — 246 Total investments $ 615,238 $ 695 $ (4 ) $ 615,929 December 31, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value US treasury notes and bills $ 467,296 $ 109 $ (69 ) $ 467,336 Term deposit 80,000 — — 80,000 Certificates of deposit 30,000 — (90 ) 29,910 Bond and mutual funds 10,464 20 — 10,484 Equity investments 125 109 — 234 Total investments $ 587,885 $ 238 $ (159 ) $ 587,964
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): March 31, 2019 December 31, 2018 Leasehold improvements $ 101,229 $ 101,200 Building shell — 53,880 Laboratory equipment 16,480 16,405 Machinery 8,396 8,382 Computer equipment 6,650 6,473 Furniture and fixtures 5,643 5,690 Construction in progress 607 367 Total property and equipment $ 139,005 $ 192,397 Less: accumulated depreciation (93,177 ) (65,199 ) Property and equipment, net $ 45,828 $ 127,198
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): March 31, 2019 December 31, 2018 Preclinical and clinical trial accruals $ 41,964 $ 35,413 Payroll and related accruals 12,368 21,430 Property taxes and other 2,969 1,095 Professional services 3,547 2,648 Other 5,430 5,537 Total accrued liabilities $ 66,278 $ 66,123

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Allocated Stock-Based Compensation Expense	Stock-based compensation expense was allocated to research and development and general and administrative expense as follows (in thousands): Three Months Ended March 31, 2019 2018 Research and development $ 9,578 $ 6,370 Selling, general and administrative 6,852 4,508 Total stock-based compensation expense $ 16,430 $ 10,878
Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan	The assumptions used to estimate the fair value of stock options granted and purchases under the Company’s 2014 Employee Share Purchase Plan (“ESPP”) using the Black-Scholes option valuation model were as follows: Three Months Ended March 31, 2019 2018 Stock Options Expected term (in years) 5.3 5.4 Expected volatility 67.9 % 67.9 % Risk-free interest rate 2.6 % 2.7 % Expected dividend yield — — Weighted average estimated fair value $ 34.14 $ 32.18 ESPPs Expected term (in years) 0.5 - 2.0 0.5 - 2.0 Expected volatility 48.1 - 62.1 % 54.9 - 75.3 % Risk-free interest rate 1.3 - 2.9 % 0.8 - 1.6 % Expected dividend yield — — Weighted average estimated fair value $ 20.57 $ 10.93

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail) - Segment	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2017
Accounting Policies [Abstract]
Number of operating segment	1
Short term investments maturity	12 months
U.S. federal statutory income tax rate	21.00%	35.00%

Summary of Significant Accounti

Summary of Significant Accounting Policies - Schedule of Impacts to Condensed Consolidated Balance Sheet Upon Adoption of 842 Guidance (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Property and equipment, net	$ 45,828	$ 127,198
Finance lease right-of-use assets	47,029	0
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	11,766	0
Deferred rent	0	3,038
Finance lease liabilities, non-current	46,818	0
Accumulated deficit	(753,161)	$ (715,827)
Derecognition Build to Suit Lease Assets [Member] | Building Shell [Member]
Assets
Property and equipment, net	(53,880)
Derecognition Build to Suit Lease Assets Accumulated Depreciation [Member] | Building Shell [Member]
Assets
Property and equipment, net	13,476
Leasehold Improvements Accumulated Depreciation [Member]
Assets
Property and equipment, net	(38,877)
Recognition Finance Lease Assets [Member]
Assets
Finance lease right-of-use assets	49,597
Recognition Operating Lease Assets [Member]
Assets
Other assets	730
Derecognition Deferred Rent Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(619)
Derecognition Build to Suit Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(545)
Recognition Operating Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	404
Recognition Finance Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	11,499
Derecognition Build to Suit Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Long-term portion of lease obligations	(95,613)
Derecognition Deferred Rent Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Deferred rent	(3,038)
Recognition Finance Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, non-current	49,884
Recognition Operating Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Other long-term liabilities	250
Cumulative Decrease to Accumulated Deficit [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accumulated deficit	$ 8,688

Summary of Significant Accoun_2

Summary of Significant Accounting Policies - Schedule of Impacts to Accumulated Other Comprehensive Loss and Accumulated Deficit Upon Adoption of Guidance (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Accounting Policy [Line Items]
Accumulated other comprehensive loss	$ (937)		$ (2,281)
Accumulated deficit	$ (753,161)		$ (715,827)
ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		$ (1,670)
Accumulated deficit		(716,438)
Impact of change in accounting principle upon adoption of ASU 2018-02 [Member] | ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		611
Accumulated deficit		$ (611)

Collaboration Agreements - Aste

Collaboration Agreements - Astellas Agreements - Additional Information (Detail) - Astellas Agreement [Member] - USD ($) $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended	35 Months Ended	45 Months Ended
	Apr. 30, 2006	Jun. 30, 2005	Mar. 31, 2019	Dec. 31, 2018	Feb. 28, 2009	Feb. 28, 2009
Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received						$ 40.1
Potential milestone payments		$ 132.5
Commercial sales milestone		15
Japan [Member] | Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		22.5
Japan [Member] | Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 95
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received					$ 320
Potential milestone payments	$ 425
Percentage of joint development costs committed to fund	50.00%
Additional consideration based on net sales description			Low 20% range
Estimated joint development extended service period				2023
Europe [Member] | Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 90
Europe [Member] | Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 335

Collaboration Agreements - Astr

Collaboration Agreements - AstraZeneca Agreements - Additional Information 1 (Detail) - AstraZeneca Agreements [Member] - USD ($) $ in Millions	Dec. 29, 2018	Dec. 17, 2018	Jul. 30, 2013	Mar. 31, 2019	Dec. 31, 2015
U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments			$ 374
Potential milestone payments			875
Commercial sales milestone			325
U.S./RoW [Member] | Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			65
U.S./RoW [Member] | Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			325
U.S./RoW [Member] | Deferred Approval Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			160
U.S./RoW [Member] | Development Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Receipt of development milestone payment					$ 15
China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			348.5
Proceeds from upfront, non-contingent and non-refundable payments			28.2
Commercial sales and other events milestone			187.5
Estimated joint development extended service period				2024
Milestone payment, revenue recognition	$ 6	$ 6
China [Member] | Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			15
China [Member] | Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 146

Collaboration Agreements - Summ

Collaboration Agreements - Summary of Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 23,863	$ 31,925
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	23,863	31,925
Astellas Agreement [Member] | License Revenue [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
Astellas Agreement [Member] | License Revenue [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
Astellas Agreement [Member] | Development Revenue [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	246	449
Astellas Agreement [Member] | Development Revenue [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	4,613	4,723
AstraZeneca Agreements [Member] | China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
AstraZeneca Agreements [Member] | License Revenue [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
AstraZeneca Agreements [Member] | Development Revenue [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 19,004	$ 26,723

Collaboration Agreements - Tran

Collaboration Agreements - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) $ in Thousands	Mar. 31, 2019USD ($)
Astellas Agreement [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	$ 88,243
Deferred Revenue	207
Total Consideration	88,450
Astellas Agreement [Member] | Japan [Member] | Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	14,154
Deferred Revenue	207
Total Consideration	14,361
Astellas Agreement [Member] | Japan [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	74,089
Deferred Revenue	0
Total Consideration	74,089
Astellas Agreement [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	577,931
Deferred Revenue	2,334
Total Consideration	580,265
Astellas Agreement [Member] | Europe [Member] | Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	207,450
Deferred Revenue	2,334
Total Consideration	209,784
Astellas Agreement [Member] | Europe [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	370,481
Deferred Revenue	0
Total Consideration	370,481
AstraZeneca Agreements [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	721,804
Deferred Revenue	144,759
Total Consideration	866,563
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	294,163
Deferred Revenue	0
Total Consideration	294,163
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	427,641
Deferred Revenue	16,787
Total Consideration	444,428
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	127,972
Total Consideration	$ 127,972

Collaboration Agreements - Su_2

Collaboration Agreements - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	$ 0.9
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	12.7
Europe [Member] | Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	0.1
U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	172.3
U.S./RoW and China [Member] | AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	$ 0.9

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 615,929	$ 587,964
US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	495,096	467,336
Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,591	10,484
Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	246	234
Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	80,000	80,000
Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	29,996	29,910
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	625,324	638,439
Fair Value, Measurements, Recurring [Member] | US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	495,096	517,270
Fair Value, Measurements, Recurring [Member] | Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,591	10,484
Fair Value, Measurements, Recurring [Member] | Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	246	234
Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	9,395	541
Fair Value, Measurements, Recurring [Member] | Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	80,000	80,000
Fair Value, Measurements, Recurring [Member] | Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	29,996	29,910
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	364,960	303,576
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	344,728	292,317
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,591	10,484
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	246	234
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	9,395	541
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	260,364	334,863
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	150,368	224,953
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	80,000	80,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	29,996	29,910
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 0	$ 0

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Values of Financial Liabilities Carried at Historical Cost (Detail) - Lease obligations [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,846	$ 98,105
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	$ 1,846	$ 98,105

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease payment liability	$ 58,584,000
Transfers of assets from level 1 to 2	0	$ 0
Transfers of assets from level 2 to 1	0	0
Transfers of liabilities from level 1 to 2	0	0
Transfers of liabilities 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 into level 3	0	0
Transfers of liabilities out of level 3	$ 0	0
Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease commencement date	2008
Lease payment liability	$ 5,000,000
Remaining lease term	2023
Building [Member] | Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease maximum expansion period	31 months
Lease obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,846,000	98,105,000
Lease obligations [Member] | Long-term property lease [Member] | Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,800,000
Lease obligations [Member] | Building [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure		$ 96,200,000

Leases - Additional Information

Leases - Additional Information (Detail) - Lease	3 Months Ended	12 Months Ended
	Mar. 31, 2019	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	4 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
Number of operating leases	4
Office Equipment [Member] | Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	3 years
Office Equipment [Member] | Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	5 years
Automobile [Member]
Lessee Lease Description [Line Items]
Number of operating leases		1
Lessee, operating lease, lease term		2 years
Lessee, operating lease, existence of option to extend		false

Leases - Schedule of Lease Asse

Leases - Schedule of Lease Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets - cost	$ 49,598
Accumulated amortization	(2,569)
Finance lease right-of-use assets, net	47,029	$ 0
Right-of-use assets - cost	730
Accumulated amortization	(122)
Operating lease right-of-use assets, net	608
Total lease assets	47,637
Finance lease liabilities	11,766	0
Operating lease liabilities	436
Finance lease liabilities	46,818	$ 0
Operating lease liabilities	129
Total lease liabilities	$ 59,149

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Finance lease cost:
Amortization of right-of-use assets	$ 2,569	$ 0
Interest on lease liabilities	640
Operating lease cost	126
Sublease income	(588)
Total lease cost	$ 2,747

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 99
Operating cash flows from finance leases	435
Financing cash flows from finance leases	3,017	$ 0
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases	49,597
Operating leases	$ 730

Leases - Schedule of Lease Term

Leases - Schedule of Lease Term and Discount Rate (Detail)	Mar. 31, 2019
Weighted-average remaining lease term (years):
Finance leases	4 years 3 months 18 days
Operating leases	1 year 2 months 12 days
Weighted-average discount rate:
Finance leases	4.43%
Operating leases	4.74%

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Mar. 31, 2019USD ($)
Finance Leases
2019 (Remaining nine month period)	$ 10,326
2020	14,106
2021	13,679
2022	13,879
2023	12,523
Total future lease payments	64,513
Less: Interest	(5,929)
Present value of lease liabilities	58,584
Operating Leases
2019 (Remaining nine month period)	326
2020	217
2021	25
2022	16
2023	0
Total future lease payments	584
Less: Interest	(19)
Present value of lease liabilities	$ 565

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 444
2020	232
2021	25
2022	16
2023	0
Total minimum payments	$ 717

Leases - Schedule of Future M_2

Leases - Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 14,379
2020	14,664
2021	14,179
2022	14,335
2023	12,872
Total minimum payments	$ 70,429

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash	$ 72,278	$ 38,783
US treasury notes and bills	0	49,934
Money market funds	9,395	541
Total cash and cash equivalents	$ 81,673	$ 89,258

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($)	Mar. 31, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 81,673,000	$ 81,673,000		$ 89,258,000
Contractual maturities of available-for-sale investments	2 years
Other-than-temporary impairment loss		0	$ 0
Building shell cost	$ 139,005,000	139,005,000		192,397,000
Accumulated depreciation	93,177,000	93,177,000		65,199,000
Building shell [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	0	0		53,880,000
Building [Member] | Build to suit arrangements [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation				13,500,000
Leasehold improvements [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	101,229,000	101,229,000		101,200,000
Leasehold improvements [Member] | Accounting standards update 2016-02 [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation	38,900,000	38,900,000
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 31,500,000	$ 31,500,000		$ 21,900,000

Balance Sheet Components - Summ

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	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 615,238	$ 587,885
Gross Unrealized Holding Gains	695	238
Gross Unrealized Holding Losses	(4)	(159)
Fair Value	615,929	587,964
US treasury notes and bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	494,580	467,296
Gross Unrealized Holding Gains	516	109
Gross Unrealized Holding Losses	0	(69)
Fair Value	495,096	467,336
Term deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	80,000	80,000
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	80,000	80,000
Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,000	30,000
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(4)	(90)
Fair Value	29,996	29,910
Bond and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,533	10,464
Gross Unrealized Holding Gains	58	20
Gross Unrealized Holding Losses	0	0
Fair Value	10,591	10,484
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	125	125
Gross Unrealized Holding Gains	121	109
Gross Unrealized Holding Losses	0	0
Fair Value	$ 246	$ 234

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 139,005	$ 192,397
Less: accumulated depreciation	(93,177)	(65,199)
Property and equipment, net	45,828	127,198
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	101,229	101,200
Building shell [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	0	53,880
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,480	16,405
Machinery [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,396	8,382
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,650	6,473
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,643	5,690
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 607	$ 367

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Preclinical and clinical trial accruals	$ 41,964	$ 35,413
Payroll and related accruals	12,368	21,430
Property taxes and other	2,969	1,095
Professional services	3,547	2,648
Other	5,430	5,537
Total accrued liabilities	$ 66,278	$ 66,123

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Allocated Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 16,430	$ 10,878
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	9,578	6,370
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 6,852	$ 4,508

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Employee stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 19 days	5 years 4 months 24 days
Expected volatility	67.90%	67.90%
Risk-free interest rate	2.60%	2.70%
Expected dividend yield	0.00%	0.00%
Weighted average estimated fair value	$ 34.14	$ 32.18
2014 Employee Share Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	48.10%	54.90%
Expected volatility, maximum	62.10%	75.30%
Risk-free interest rate, minimum	1.30%	0.80%
Risk-free interest rate, maximum	2.90%	1.60%
Expected dividend yield	0.00%	0.00%
Weighted average estimated fair value	$ 20.57	$ 10.93
2014 Employee Share Purchase Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months
2014 Employee Share Purchase Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years	2 years

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Accounts receivable from related party	$ 3,898		$ 47,210
Accrued liabilities to related party	519		444
Astellas [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	4,900	$ 5,200
Expense related to collaboration agreements	500	$ 600
Accounts receivable from related party	3,900		47,200
Accrued liabilities to related party	$ 500		400
Astellas [Member] | Astellas Agreement [Member] | API Shipment [Member]
Related Party Transaction [Line Items]
Accrued liabilities to related party			$ 43,800