Sage Therapeutics (SAGE) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 29, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	SAGE
Entity Registrant Name	Sage Therapeutics, Inc.
Entity Central Index Key	0001597553
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		52,044,663
Entity Shell Company	false
Entity File Number	001-36544
Entity Tax Identification Number	27-4486580
Entity Address, Address Line One	215 First Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	299-8380
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 184,270	$ 126,705
Marketable securities	484,267	881,688
Prepaid expenses and other current assets	30,347	26,700
Total current assets	698,884	1,035,093
Property and equipment, net	7,404	9,126
Restricted cash	2,367	2,367
Right-of-use operating asset	26,546	33,771
Other long-term assets	3,427	3,793
Total assets	738,628	1,084,150
Current liabilities:
Accounts payable	4,289	15,266
Accrued expenses	46,756	86,618
Operating lease liability, current portion	8,620	10,244
Total current liabilities	59,665	112,128
Operating lease liability, net of current portion	21,069	26,848
Other liabilities	313	519
Total liabilities	81,047	139,495
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, $0.0001 par value per share; 5,000,000 shares authorized at September 30, 2020 and December 31, 2019; no shares issued or outstanding at September 30, 2020 and December 31, 2019
Common stock, $0.0001 par value per share; 120,000,000 shares authorized at September 30, 2020 and December 31, 2019; 52,025,862 and 51,880,227 shares issued at September 30, 2020 and December 31, 2019; 52,022,829 and 51,877,194 shares outstanding at September 30, 2020 and December 31, 2019	5	5
Treasury stock, at cost, 3,033 shares at September 30, 2020 and December 31, 2019	(400)	(400)
Additional paid-in capital	2,669,419	2,587,322
Accumulated deficit	(2,012,389)	(1,643,567)
Accumulated other comprehensive gain	946	1,295
Total stockholders’ equity	657,581	944,655
Total liabilities and stockholders’ equity	$ 738,628	$ 1,084,150

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	52,025,862	51,880,227
Common stock, shares outstanding	52,022,829	51,877,194
Treasury stock, shares	3,033	3,033

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total revenue	$ 1,639	$ 3,570	$ 5,014	$ 4,908
Type of Revenue [Extensible List]	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember
Operating costs and expenses:
Cost of goods sold	$ 149	$ 137	$ 429	$ 181
Research and development	74,078	102,108	211,008	277,565
Selling, general and administrative	35,099	88,502	143,454	260,648
Restructuring	(529)		27,873
Total operating costs and expenses	108,797	190,747	382,764	538,394
Loss from operations	(107,158)	(187,177)	(377,750)	(533,486)
Interest income, net	1,347	7,227	8,763	21,889
Other income (expense), net	76	(8)	165	12
Net loss	$ (105,735)	$ (179,958)	$ (368,822)	$ (511,585)
Net loss per share—basic and diluted	$ (2.03)	$ (3.48)	$ (7.10)	$ (10.13)
Weighted average number of common shares outstanding—basic and diluted	51,981,468	51,704,687	51,938,923	50,496,489
Comprehensive loss:
Net loss	$ (105,735)	$ (179,958)	$ (368,822)	$ (511,585)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	(763)	202	(349)	2,292
Total other comprehensive gain (loss)	(763)	202	(349)	2,292
Total comprehensive loss	(106,498)	(179,756)	(369,171)	(509,293)
Product Revenue [Member]
Total revenue	$ 1,639	1,478	$ 5,014	1,997
Collaboration Revenue [Member]
Total revenue		$ 2,092		$ 2,911

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (368,822)	$ (511,585)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	75,250	122,552
Premium on marketable securities	(1,066)	(2,652)
Amortization of premium (discount) on marketable securities	628	(6,429)
Depreciation	1,981	1,618
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,647)	(8,494)
Other long-term assets	366	(3,818)
Right-of-use operating asset	4,914	6,424
Operating lease liabilities, current	(6)	116
Operating lease liabilities, non-current	(5,194)	(6,249)
Accounts payable	(10,913)	(28,955)
Accrued expenses and other liabilities	(40,182)	25,492
Net cash used in operating activities	(346,691)	(411,980)
Cash flows from investing activities
Proceeds from sales and maturities of marketable securities	766,339	957,840
Purchases of marketable securities	(368,829)	(1,077,702)
Purchases of property and equipment	(345)	(5,378)
Net cash provided by (used in) investing activities	397,165	(125,240)
Cash flows from financing activities
Proceeds from stock option exercises and employee stock purchase plan issuances	7,091	46,684
Payment of employee tax obligations related to vesting of restricted stock units		(2,175)
Payments of offering costs		(328)
Proceeds from public offerings of common stock, net of commissions and underwriting discounts		561,277
Net cash provided by financing activities	7,091	605,458
Net increase in cash, cash equivalents and restricted cash	57,565	68,238
Cash, cash equivalents and restricted cash at beginning of period	129,072	193,310
Cash, cash equivalents and restricted cash at end of period	186,637	261,548
Supplemental disclosure of non-cash operating and investing activities
Purchases of property and equipment included in accounts payable		11
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 872
Lease asset de-recognized upon lease cancellation	$ 2,310

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balances at Dec. 31, 2018	$ 862,971	$ 5	$ (211)	$ 1,827,021	$ (515)	$ (963,329)
Balances, Shares at Dec. 31, 2018		46,888,263	3,033
Issuance of common stock from exercises of stock options, Amount	14,072			14,072
Issuance of common stock from exercises of stock options, Shares		287,659
Issuance of common stock under the employee stock purchase plan	1,799			1,799
Issuance of common stock under the employee stock purchase plan, Shares		16,398
Purchase of treasury stock, Amount	(189)		$ (189)
Stock-based compensation expense	43,622			43,622
Public offering of common stock, net of offering costs, Amount	560,948			560,948
Public offering of common stock, net of offering costs, Shares		3,833,334
Unrealized gain (loss) on available-for-sale securities	409				409
Vesting of restricted stock units, net of employee tax obligations	(692)			(692)
Vesting of restricted stock units, net of employee tax obligations, Shares		8,518
Net loss	(163,406)					(163,406)
Balances at Mar. 31, 2019	1,319,534	$ 5	$ (400)	2,446,770	(106)	(1,126,735)
Balances, Shares at Mar. 31, 2019		51,034,172	3,033
Balances at Dec. 31, 2018	862,971	$ 5	$ (211)	1,827,021	(515)	(963,329)
Balances, Shares at Dec. 31, 2018		46,888,263	3,033
Net loss	(511,585)
Balances at Sep. 30, 2019	1,081,071	$ 5	$ (400)	2,554,603	1,777	(1,474,914)
Balances, Shares at Sep. 30, 2019		51,815,992	3,033
Balances at Mar. 31, 2019	1,319,534	$ 5	$ (400)	2,446,770	(106)	(1,126,735)
Balances, Shares at Mar. 31, 2019		51,034,172	3,033
Issuance of common stock from exercises of stock options, Amount	15,601			15,601
Issuance of common stock from exercises of stock options, Shares		434,932
Stock-based compensation expense	34,280			34,280
Unrealized gain (loss) on available-for-sale securities	1,681				1,681
Net loss	(168,221)					(168,221)
Balances at Jun. 30, 2019	1,202,875	$ 5	$ (400)	2,496,651	1,575	(1,294,956)
Balances, Shares at Jun. 30, 2019		51,469,104	3,033
Issuance of common stock from exercises of stock options, Amount	12,436			12,436
Issuance of common stock from exercises of stock options, Shares		248,196
Issuance of common stock under the employee stock purchase plan	3,946			3,946
Issuance of common stock under the employee stock purchase plan, Shares		39,006
Stock-based compensation expense	43,053			43,053
Unrealized gain (loss) on available-for-sale securities	202				202
Vesting of restricted stock units, net of employee tax obligations	(1,483)			(1,483)
Vesting of restricted stock units, net of employee tax obligations, Shares		59,686
Net loss	(179,958)					(179,958)
Balances at Sep. 30, 2019	1,081,071	$ 5	$ (400)	2,554,603	1,777	(1,474,914)
Balances, Shares at Sep. 30, 2019		51,815,992	3,033
Balances at Dec. 31, 2019	944,655	$ 5	$ (400)	2,587,322	1,295	(1,643,567)
Balances, Shares at Dec. 31, 2019		51,877,194	3,033
Issuance of common stock from exercises of stock options, Amount	367			367
Issuance of common stock from exercises of stock options, Shares		7,196
Issuance of common stock under the employee stock purchase plan	2,793			2,793
Issuance of common stock under the employee stock purchase plan, Shares		33,429
Stock-based compensation expense	30,218			30,218
Unrealized gain (loss) on available-for-sale securities	(2,087)				(2,087)
Net loss	(126,740)					(126,740)
Balances at Mar. 31, 2020	849,206	$ 5	$ (400)	2,620,700	(792)	(1,770,307)
Balances, Shares at Mar. 31, 2020		51,917,819	3,033
Balances at Dec. 31, 2019	944,655	$ 5	$ (400)	2,587,322	1,295	(1,643,567)
Balances, Shares at Dec. 31, 2019		51,877,194	3,033
Net loss	(368,822)
Balances at Sep. 30, 2020	657,581	$ 5	$ (400)	2,669,419	946	(2,012,389)
Balances, Shares at Sep. 30, 2020		52,022,829	3,033
Balances at Mar. 31, 2020	849,206	$ 5	$ (400)	2,620,700	(792)	(1,770,307)
Balances, Shares at Mar. 31, 2020		51,917,819	3,033
Issuance of common stock from exercises of stock options, Amount	387			387
Issuance of common stock from exercises of stock options, Shares		17,160
Stock-based compensation expense	24,168			24,168
Unrealized gain (loss) on available-for-sale securities	2,501				2,501
Net loss	(136,347)					(136,347)
Balances at Jun. 30, 2020	739,915	$ 5	$ (400)	2,645,255	1,709	(1,906,654)
Balances, Shares at Jun. 30, 2020		51,934,979	3,033
Issuance of common stock from exercises of stock options, Amount	2,157			2,157
Issuance of common stock from exercises of stock options, Shares		48,560
Issuance of common stock under the employee stock purchase plan	2,144			2,144
Issuance of common stock under the employee stock purchase plan, Shares		39,290
Stock-based compensation expense	19,863			19,863
Unrealized gain (loss) on available-for-sale securities	(763)				(763)
Net loss	(105,735)					(105,735)
Balances at Sep. 30, 2020	$ 657,581	$ 5	$ (400)	$ 2,669,419	$ 946	$ (2,012,389)
Balances, Shares at Sep. 30, 2020		52,022,829	3,033

Nature of the Business

Nature of the Business	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business Sage Therapeutics, Inc. (“Sage” or the “Company”) is a biopharmaceutical company committed to developing and commercializing novel medicines with the potential to transform the lives of people with debilitating disorders of the brain. The Company’s first product, ZULRESSO® (brexanolone) CIV injection, was approved by the U.S. Food and Drug Administration (“FDA”) in March 2019 for the treatment of postpartum depression (“PPD”) in adults, and was made commercially available in the U.S. beginning on June 24, 2019, after completion of controlled substance scheduling of brexanolone by the U.S. Drug Enforcement Administration and incorporation of the scheduling into the FDA-approved label and other product information. The Company has a portfolio of other product candidates with a current focus on modulating two critical central nervous system (“CNS”) receptor systems, GABA and NMDA. The GABA receptor family, which is recognized as the major inhibitory neurotransmitter in the CNS, mediates downstream neurologic and bodily function via activation of GABA A The Company was incorporated under the laws of the State of Delaware on April 16, 2010, and commenced operations on January 19, 2011 as Sterogen Biopharma, Inc. On September 13, 2011, the Company changed its name to Sage Therapeutics, Inc. The Company is subject to risks and uncertainties common to companies in the biotechnology and pharmaceutical industries, including, but not limited to, the risks associated with developing product candidates at each stage of non-clinical and clinical development; the challenges associated with gaining regulatory approval of such product candidates; the risks associated with the marketing and sale of pharmaceutical products; the potential for development by third parties of new technological innovations that may compete with the Company’s products and product candidates; the dependence on key personnel; the challenges of protecting proprietary technology; the need to comply with government regulations; the high costs of drug development; the impact of the COVID-19 pandemic on its operations and financial condition; and the uncertainty of being able to secure additional capital when needed to fund operations. Under Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern Until such time, if ever, as the Company can generate substantial product revenue and achieve profitability, the Company expects to finance its cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other sources of funding. If the Company is unable to raise additional funds through equity or debt financings or other sources of funding when needed, the Company may be required to delay, limit, reduce or terminate product development or future commercialization efforts or grant rights to develop and market products or product candidates that the Company would otherwise prefer to develop and market itself. The Company expects that, based on its current operating plans, the Company’s existing cash, cash equivalents and marketable securities will be sufficient to fund its current planned operations for at least the next twelve months from the issuance of these unaudited interim condensed consolidated financial statements (“condensed consolidated financial statements”). COVID-1 9 The ongoing COVID-19 pandemic has caused and may continue to cause major disruptions to businesses and financial markets worldwide. The rapid spread of COVID-19 in the U.S. has resulted in a significant reduction in patient demand for ZULRESSO and in the number of sites available to administer ZULRESSO. This has had a negative impact on the Company’s revenue from sales of ZULRESSO. While there have been no material disruptions to date, any prolonged material disruptions to the work of the Company’s employees, suppliers, contract manufacturers, or vendors as a result of the COVID-19 pandemic could negatively impact the Company’s activities, availability of supplies, or operating results. Similarly, any material disruption to the Company’s development activities as a result of the COVID-19 pandemic may cause delays, increase the Company’s costs and impact the Company’s operating results. In addition, the COVID-19 pandemic has caused major volatility in capital markets and a significant global economic downturn, and the Company’s ability to access the capital markets in the future could be negatively impacted if volatility in the capital markets and the economic downturn continue.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The following is a summary of significant accounting policies followed in the preparation of these condensed consolidated financial statements. Basis of Presentation The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. The condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of the Company’s management, the accompanying condensed consolidated financial statements contain all adjustments, consisting of only normal recurring adjustments, necessary for a fair statement of its financial position as of September 30, 2020, its results of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, its cash flows for the nine months ended September 30, 2020 and 2019, and its statements of changes in stockholders’ equity for the three and nine months ended September 30, 2020 and 2019. The consolidated balance sheet at December 31, 2019 was derived from audited financial statements, but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results for the year ending December 31, 2020, or for any future period. Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, within the “Notes to Consolidated Financial Statements” accompanying its Annual Report on Form 10-K for the fiscal year ended December 31, 2019. Intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including sales, expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including developments related to the scope and duration of the pandemic; the timing, extent and frequency of surges in the number of cases of COVID-19; new information that may emerge concerning COVID-19; and the actions taken to contain the COVID-19 pandemic. The Company has made estimates of the impact of the COVID-19 pandemic within its consolidated financial statements, and there may be changes to those estimates in future periods. Research and Development Costs and Accruals Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, depreciation, contract services and other related costs. Research and development costs are expensed to operations as the related obligation is incurred. The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the U.S. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of the end of the reporting period Stock-Based Compensation The Company recognizes compensation expense for stock-based awards, including grants of stock options and restricted stock units, made to employees and non-employee directors based on the estimated fair value on the date of grant, over the requisite service period. The Company recognizes stock-based compensation expense for only the portion of awards that are expected to vest. For awards that vest upon achievement of a performance condition, the Company recognizes compensation expense when achievement of the performance condition is met or during the period from which meeting the condition is deemed probable until the expected date of meeting the performance condition. The fair value of each option grant is estimated using the Black-Scholes option-pricing model. Through December 31, 2015, the Company lacked sufficient Company-specific historical and implied volatility information, and as a result, the Company used the volatility of a group of publicly-traded peer companies in the Black-Scholes calculations. Beginning in 2016, the Company estimated its expected volatility using a weighted average of the historical volatility of publicly-traded peer companies and the volatility of its common stock and expected to continue to do so until such time as it has adequate historical data regarding the volatility of its common stock price for the duration of the expected term. Effective January 1, 2020, the Company began using the historical volatility of only its common stock, as there is adequate historical data for the duration of the expected term. The expected term of the options granted to employees and non-employee directors by the Company has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. Through December 31, 2018, the expected term of the options granted to non-employee consultants was determined based on the contractual term of the options, and since January 1, 2019, the “simplified” method has been used. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The Company also applies a forfeiture rate in order to calculate stock-based compensation expense. Expected forfeitures are based on the historical experience of the Company and management’s expectations of future forfeitures. To the extent actual forfeitures differ from the estimates, the difference is recorded as a cumulative adjustment in the period in which the estimates are revised. Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the date of purchase to be cash equivalents. As of September 30, 2020, cash equivalents were comprised of money market funds. As of December 31, 2019, cash equivalents were comprised of commercial paper and money market funds. Marketable securities Marketable securities consist of investments with original maturities greater than 90 days. The Company has classified its investments with maturities beyond one year as short-term, based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. The Company considers its investment portfolio of marketable securities to be available-for-sale. Accordingly, these investments are recorded at fair value, which is based on quoted market prices. Unrealized gains and losses are reported as the accumulated other comprehensive items in stockholders’ equity. When the fair value is below the amortized cost of the asset, an estimate of expected credit losses is made. The credit-related impairment amount is recognized in net income; the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in net income. Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories: Level 1 — Quoted market prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s cash equivalents and marketable securities at September 30, 2020 and December 31, 2019 were carried at fair value, determined according to the fair value hierarchy; see Note 3, Fair Value Measurements. The carrying amounts reflected in the condensed consolidated balance sheets for accounts payable and accrued expenses approximate their fair values due to their short-term maturities at September 30, 2020 and December 31, 2019, respectively. Revenue Recognition The Company received approval of ZULRESSO from the FDA in March 2019 and subsequently began to record revenues from product sales in June 2019. Prior to the second quarter of 2019, all of the revenues of the Company were derived from the Company’s collaboration agreement and supply agreement with Shionogi & Co., Ltd. (“Shionogi”). The terms of the Company’s collaboration agreement include consideration such as non-refundable license fees, reimbursement of any development costs the Company incurs on behalf of Shionogi, payments due upon the achievement, if any, of clinical and pre-clinical performance-based development milestones, regulatory milestones, and sales-based milestones and royalties on product sales, if development is successful in the Shionogi territory, as well as payments for the supply of active pharmaceutical ingredient (“API”) and drug product for clinical trials. To date, revenue from the Company’s collaboration agreement with Shionogi has come from an initial, upfront license fee upon execution of the agreement and from the supply of API for Shionogi’s clinical trials. Under Accounting Standards Codification (“ASC”) Topic 606, “ Revenue from Contracts with Customers Product revenue The Company recognizes product revenues, net of variable consideration related to certain allowances and accruals that are determined using the expected value method, in its condensed consolidated financial statements at the point in time when control transfers to the customer, which is typically when the product has been delivered to the customer’s location. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. The Company’s only performance obligation identified for ZULRESSO is to deliver the product to the location specified by the customer’s order. The Company records shipping and handling costs associated with delivery of product to its customers within selling, general and administrative expenses on its condensed consolidated statements of operations and comprehensive loss. The Company expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset would be less than one year. If the Company were to incur incremental costs with an amortization period greater than a year, such costs would be capitalized as contract assets, as they are expected to be recovered, and would be expensed by amortizing on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. The Company did not have any contract assets (unbilled receivables) at September 30, 2020, as customer invoicing generally occurs before or at the time of revenue recognition. The Company did not have any contract liabilities at September 30, 2020, as the Company did not receive any payments in advance of satisfying its performance obligations to its customers. Amounts billed or invoiced are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. The Company records reserves, based on contractual terms, for components of variable consideration related to product sold during the reporting period, as well as its estimate of product that remains in the distribution channel inventory of its customers at the end of the reporting period. On a quarterly basis, the Company updates its estimates and records any necessary material adjustments in the period they are identified. Inventory Inventory is stated at the lower of cost or estimated net realizable value with cost determined on a first-in, first-out basis. Inventory costs include raw materials, third-party contract manufacturing, third-party packaging services, and freight. Raw and intermediate materials that may be utilized for either research and development or commercial purposes are identical and, as a result, are both classified as inventory. Amounts in inventory associated with research and development are charged to research and development expense when the product enters the research and development process and can no longer be used for commercial purposes and, therefore, does not have an “alternative future use” as defined in authoritative guidance. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period and writes down any excess and obsolete inventory to its estimated net realizable value in the period it is identified. If they occur, such impairment charges are recorded as a component of cost of goods sold in the condensed consolidated statements of operations and comprehensive loss. Inventory is included in prepaid expenses and other current assets on the condensed consolidated balance sheets and the amount was not significant as of September 30, 2020. Prior to the initial date regulatory approval is received, costs related to the production of inventory are recorded as research and development expense on the Company’s condensed consolidated statements of operations and comprehensive loss in the period incurred. The Company received FDA approval for ZULRESSO on March 19, 2019 and subsequently began capitalizing costs related to inventory manufacturing. Cost of Goods Sold Cost of goods sold includes direct and indirect costs related to the manufacturing and distribution of ZULRESSO, including third-party manufacturing costs, packaging services, freight, third-party royalties payable on the Company’s net product revenues and amortization of intangible assets associated with ZULRESSO. Cost of goods sold may also include period costs related to certain inventory manufacturing services, inventory adjustment charges, as well as manufacturing variances. In connection with the FDA approval of ZULRESSO on March 19, 2019, the Company subsequently began capitalizing inventory manufactured or purchased after this date. As a result, certain manufacturing costs associated with product shipments of ZULRESSO were expensed prior to FDA approval and, therefore, are not included in cost of goods sold during the three and nine months ended September 30, 2020 and 2019. Accounts Receivable The Company’s trade accounts receivable consist of amounts due from specialty distributors, specialty pharmacies and medically-supervised healthcare settings that have been certified under a Risk Evaluation and Mitigation Strategy (“REMS”) program in the U.S. related to sales of ZULRESSO and have standard payment terms that generally require payment within 30 to 90 days from the invoice date. The Company monitors the financial performance and creditworthiness of customers so that it can properly assess and respond to changes in their credit profile. The Company reserves against trade accounts receivable for estimated losses that may arise from a customer’s inability to pay and any amounts determined to be uncollectible are written off against the reserve when it is probable that the receivable will not be collected. Trade accounts receivable are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. As of September 30, 2020, the Company has not provided any allowance for bad debts against the trade accounts receivable, and the amount of trade accounts receivable was not significant. Leases The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term, and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit interest rate when readily determinable and uses the Company’s incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The lease payments used to determine the Company’s operating lease assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation, when determinable, and are recognized in the Company’s operating lease assets in the Company’s condensed consolidated balance sheets. In addition, the Company’s contracts contain lease and non-lease components. The Company combines lease and non-lease components, which are accounted for together as lease components. The Company’s operating leases are reflected in the right-of-use operating asset; operating lease liability, current portion; and operating lease liability, net of current portion in the Company’s condensed consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Short-term leases, defined as leases that have a lease term of 12 months or less at the commencement date, are excluded from this treatment and are recognized on a straight-line basis over the term of the lease. Variable lease payments are the amounts owed by the Company to a lessor that are not fixed, such as reimbursement for common area maintenance and utilities costs for facility leases and maintenance and tolls for leased vehicles. Variable lease payments are expensed when incurred. Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (Topic 842) Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements Narrow-Scope Improvement for Lessors Leases (Topic 842): Codification Improvements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . This standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. For available-for-sale debt securities, entities are required to recognize an allowance for credit losses rather than a reduction in carrying value of the asset. Entities are no longer permitted to consider the length of time that fair value has been less than amortized cost when evaluating when credit losses should be recognized. The Company adopted the standard on the required effective date of January 1, 2020, on a prospective basis. This guidance did not have a significant impact on the Company’s condensed consolidated financial statements and related disclosures . In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement The Company adopted the standard on the required effective date of January 1, 2020. This guidance did not have a significant impact on the Company’s condensed consolidated financial statements and related disclosures In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company’s cash equivalents are classified within Level 1 and Level 2 of the fair value hierarchy. The Company’s investments in marketable securities are classified within Level 2 of the fair value hierarchy. The fair values of the Company’s marketable securities are based on prices obtained from independent pricing sources. Consistent with the fair value hierarchy described in Note 2, Summary of Significant Accounting Policies, securities with validated quotes from pricing services are reflected within Level 2, as they are primarily based on observable pricing for similar assets or other market observable inputs. Typical inputs used by these pricing services include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers or estimates of cash flow, prepayment spreads and default rates. The following tables summarize the Company’s cash equivalents and marketable securities as of September 30, 2020 and December 31, 2019. September 30, 2020 Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (in thousands) Cash equivalents: Cash equivalents $ 184,270 $ 184,270 $ — $ — Total cash equivalents 184,270 184,270 — — Marketable securities: U.S. government securities 172,742 — 172,742 — U.S. corporate bonds 174,964 — 174,964 — International corporate bonds 65,682 — 65,682 — U.S. commercial paper 40,947 — 40,947 — International commercial paper 29,932 — 29,932 — Total marketable securities 484,267 — 484,267 — $ 668,537 $ 184,270 $ 484,267 $ — December 31, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (in thousands) Cash equivalents: Cash equivalents $ 126,705 $ 65,414 $ 61,291 $ — Total cash equivalents 126,705 65,414 61,291 — Marketable securities: U.S. government securities 205,328 — 205,328 — U.S. corporate bonds 429,845 — 429,845 — International corporate bonds 142,998 — 142,998 — U.S. commercial paper 52,261 — 52,261 — International commercial paper 51,256 — 51,256 — Total marketable securities 881,688 — 881,688 — $ 1,008,393 $ 65,414 $ 942,979 $ — During the nine months ended September 30, 2020 and 2019, there were no transfers among the Level 1, Level 2 and Level 3 categories. The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of September 30, 2020 and December 31, 2019: September 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Credit Losses Fair Value (in thousands) Assets: U.S. government securities $ 172,685 $ 72 $ (15 ) $ — $ 172,742 U.S. corporate bonds 174,465 514 (15 ) — 174,964 International corporate bonds 65,291 391 — — 65,682 U.S. commercial paper 40,948 1 (2 ) — 40,947 International commercial paper 29,932 — — — 29,932 $ 483,321 $ 978 $ (32 ) $ — $ 484,267 December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Assets: U.S. government securities $ 205,172 $ 176 $ (20 ) $ 205,328 U.S. corporate bonds 429,148 797 (100 ) 429,845 International corporate bonds 142,568 457 (27 ) 142,998 U.S. commercial paper 52,252 14 (5 ) 52,261 International commercial paper 51,253 5 (2 ) 51,256 $ 880,393 $ 1,449 $ (154 ) $ 881,688 As of September 30, 2020, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for corporate bonds with a fair value of $18.9 million, that had maturities of one to two years. As of December 31, 2019, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for corporate bonds with a fair value of $137.1 million, that had maturities of one to two years. As of September 30, 2020 , the marketable securities in a loss position had a maturity of less than one year, except for corporate bonds with a fair value of $4.0 million, that had maturities of one to two years. As of December 31, 2019, the marketable securities in a loss position had a maturity of less than one year. There have been no impairments of the Company’s assets measured and carried at fair value during the nine months ended September 30, 2020 and the year ended December 31, 2019.

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, net Property and equipment, net, consists of the following: September 30, December 31, 2020 2019 (in thousands) Computer hardware and software $ 2,758 $ 2,830 Furniture and equipment 1,865 1,828 Leasehold improvements 9,220 8,967 13,843 13,625 Less: Accumulated depreciation (6,439 ) (4,499 ) $ 7,404 $ 9,126 Depreciation expense for the three months ended September 30, 2020 and 2019 was $0.7 million and $0.7 million, respectively. Depreciation expense for the nine months ended September 30, 2020 and 2019 was $2.0 million and $1.6 million, respectively. The useful life for computer hardware and software is three years, furniture and equipment is five years and leasehold improvements is the lesser of the useful life or the term of the respective lease. Accrued Expenses Accrued expenses consist of the following: September 30, December 31, 2020 2019 (in thousands) Accrued research and development costs $ 29,233 $ 46,940 Restructuring 1,356 - Employee-related 9,147 22,011 Professional services 6,045 16,720 Other 975 947 $ 46,756 $ 86,618

Leases, Commitments and Conting

Leases, Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Leases, Commitments and Contingencies	5. Leases, Commitments and Contingencies Operating Leases The Company has leases for office space, vehicles, and certain equipment. All of the leases recorded on the condensed consolidated balance sheets are operating leases. The Company’s leases have remaining lease terms ranging from less than one year to approximately six years. Some of the leases include options to extend the leases for up to five years. These options were not included for the purpose of determining the right-of-use assets and associated lease liabilities as the Company determined that the renewal of these leases is not reasonably certain so only the original lease term was taken into consideration. The leases do not include any restrictions or covenants that had to be accounted for under the lease guidance. From June 2018 to January 2019, the Company entered into leases for vehicles for field-based employees. These leases were determined to be operating leases and a right-of-use operating asset in the amount of $5.3 million was recorded on the balance sheet upon implementation of the new lease standard on January 1, 2019. The leases were for a term of three years and were to expire on various dates through January 31, 2022. During the three months ended June 30, 2020, these leases were terminated as part of the restructuring (see Note 10, Restructuring), and the remaining asset of $2.3 million and the liabilities related to these leases were de-recognized upon termination of the leases. As of January 1, 2019, the Company leased office space in two multi-tenant buildings in Cambridge, Massachusetts, consisting of 58,442 square feet in the first building under an operating lease that will expire on August 15, 2024, 40,419 square feet in the second building under an operating lease that will expire on August 31, 2024; and in a multi-tenant building in Raleigh, North Carolina, consisting of 15,525 square feet under an operating lease that will expire on November 30, 2024. In December 2018, the Company entered into a lease for office space in a third multi-tenant building in Cambridge, Massachusetts. The amount of square feet of office space is 15,975 square feet and the lease period began on March 1, 2019. The term for this lease will expire on February 29, 2024. In March 2019, the Company entered into the Eighth Amendment to the lease for office space in the first multi-tenant building and thereby increased the amount of square feet of office space from 58,442 square feet to 63,017 square feet. The increase of 4,575 square feet began on June 1, 2019. The term for this additional space will expire on August 31, 2024. License Agreements CyDex License Agreement In September 2015, the Company and CyDex Pharmaceuticals, Inc. (“CyDex”), a wholly owned subsidiary of Ligand Pharmaceuticals, Inc., amended and restated their existing commercial license agreement. Under the terms of the commercial license agreement as amended and restated, CyDex has granted to the Company an exclusive license to CyDex’s Captisol drug formulation technology and related intellectual property for the manufacture of pharmaceutical products incorporating brexanolone and the Company’s compound known as SAGE-689, and the development and commercialization of the resulting products in the treatment, prevention or diagnosis of any disease or symptom in humans or animals other than (i) the ocular treatment of any disease or condition with a formulation, including a hormone; (ii) topical ocular treatment of inflammatory conditions; (iii) treatment and prophylaxis of fungal infections in humans; and (iv) any ocular treatment for retinal degeneration. The Company is required to pay a royalty to CyDex on sales of brexanolone and will be required to pay a royalty on sales of SAGE-689, if such product candidate is successfully developed in the future Under the amended and restated license agreement with CyDex, the Company agreed to make milestone payments on the achievement of clinical development and regulatory milestones in the amount of up to $0.8 million in clinical milestones and up to $3.8 million in regulatory milestones for each of the first two fields with respect to brexanolone; up to $ 1.3 million in clinical milestones and up to $ 8.5 million in regulatory milestones for each of the third and fourth fields with respect to brexanolone; and up to $ 0.8 million in clinical milestones and up to $ 1.8 million in regulatory milestones for one field with respect to SAGE-689. As of September 30, 2020 , the Company has recorded research and development expense and made cash payments of $ 2.3 million related to these clinical development and regulatory milestones and has recorded an intangible asset and made a cash payment of $3.0 million related to these regulatory milestones . For the three and nine months ended September 30, 2020, and the three months ended September 30, 2019, the Company did not record any expense or intangible asset, or make any milestone payments related to clinical development or regulatory milestones for the brexanolone program or SAGE-689 under the license agreement with CyDex. For the nine months ended September 30, 2019, the Company recorded an intangible asset of $3.0 million related to a regulatory milestone for the brexanolone program under the license agreement with CyDex. As of September 30, 2020, the Company has made no milestone payments related to clinical development or regulatory milestones for SAGE-689 under the license agreement with CyDex. University of California License Agreements In October 2013, the Company entered into a non-exclusive license agreement with The Regents of the University of California under which the Company was granted a non-exclusive license to certain clinical data and clinical material related to brexanolone for use in the development and commercialization of biopharmaceutical products in the licensed field, including status epilepticus and postpartum depression. In May 2014, the license agreement was amended to add the treatment of essential tremor to the licensed field of use, materials and milestone fee provisions of the agreement. The Company paid to The Regents of the University of California clinical development milestones of $0.1 million, prior to December 31, 2015; no other milestones are outstanding under this non-exclusive license agreement. The Company is required to pay royalties of less than 1% on net sales for a period of fifteen years following the sale of the first product developed using the data and materials. The license will terminate on the earlier to occur of (i) 27 years after the effective date or (ii) 15 years after the last-derived product is first commercially sold. In June 2015, the Company entered into an exclusive license agreement with The Regents of the University of California whereby the Company was granted an exclusive license to certain patent rights related to the use of allopregnanolone to treat various diseases. In exchange for such license, the Company paid an upfront payment of $50,000 and will make payments of $15,000 for annual maintenance fees until the calendar year following the first sale, if any, of a licensed product. The Company is obligated to make milestone payments following the achievement of specified regulatory and sales milestones of up to $0.7 million and $2.0 million in the aggregate, respectively. Following the first sale of a licensed product, the Company is required to pay royalties at a low single digit percentage of net sales of licensed products, subject to specified minimum annual royalty amounts. Unless terminated by operation of law or by acts of the parties under the terms of the agreement, the license agreement will terminate when the last-to-expire patents or last-to-be abandoned patent applications expire, whichever is later. As of September 30, 2020, the Company has recorded research and development expense and made cash payments of $0.3 million related to these regulatory and sales milestones; and has recorded an intangible asset and made a cash payment of $0.5 million related to these regulatory and sales milestones. For the three and nine months ended September 30, 2020, and the three months ended September 30, 2019, the Company did not record any expense or make any milestone payments under the license agreements with The Regents of the University of California. For the nine months ended September 30, 2019, the Company recorded an intangible asset and made a cash payment of $0.5 million related to a regulatory milestone under the license agreements with The Regents of the University of California. Washington University License Agreement In November 2013, the Company entered into a license agreement with Washington University whereby the Company was granted exclusive, worldwide rights to develop and commercialize a novel set of neuroactive steroids developed by Washington University. In exchange for development and commercialization rights, the Company paid an upfront, non-refundable payment of $50,000 and is required to pay an annual license maintenance fee of $15,000 on each subsequent anniversary date, until the first Phase 2 clinical trial for a licensed product is initiated. The Company is obligated to make milestone payments to Washington University based on achievement of clinical development and regulatory milestones of up to $0.7 million and $0.5 million, respectively. Additionally, the Company fulfilled its obligation to issue to Washington University 47,619 shares of common stock on December 13, 2013. The fair value of these shares of $ 0.1 million was recorded as research and development expense in 2013 . As of September 30, 2020 , the Company has recorded research and development expense and made a cash payment of $ 50,000 related to these clinical development milestones. The Company is obligated to pay royalties to Washington University at rates in the low single digits on net sales of licensed products covered under patent rights and royalties at rates in the low single digits on net sales of licensed products not covered under patent rights. Additionally, the Company has the right to sublicense and is required to make payments at varying percentages of sublicensing revenue received, initially in the mid-teens and descending to the mid-single digits over time. For the three and nine months ended September 30, 2020 and 2019, the Company did not record any expense or make any milestone payments under the license agreement with Washington University.

Collaboration Agreement

Collaboration Agreement	9 Months Ended
	Sep. 30, 2020
Collaboration Agreement [Abstract]
Collaboration Agreement	6. Collaboration Agreement Effective June 12, 2018, the Company entered into a strategic collaboration with Shionogi for the clinical development and commercialization of zuranolone for the treatment of major depressive disorder (“MDD”) and other potential indications in Japan, Taiwan and South Korea. On October 26, 2018, the Company entered into a supply agreement with Shionogi for zuranolone clinical material. Under the terms of the collaboration agreement, Shionogi will be responsible for all clinical development, regulatory filings and commercialization of zuranolone for MDD, and potentially other indications, in Japan, Taiwan and South Korea. Shionogi was required to make an upfront payment to the Company of $90.0 million, and the Company will be eligible to receive additional payments of up to $485.0 million if certain regulatory and commercial milestones are achieved by Shionogi. The potential future milestone payments include up to $70.0 million for the achievement of specified regulatory milestones, up to $30.0 million for the achievement of specified commercialization milestones, and up to $385.0 million for the achievement of specified net sales milestones. The Company is eligible to receive tiered royalties on sales of zuranolone in Japan, Taiwan and South Korea, if development efforts are successful, with tiers averaging in the low to mid-twenty percent range, subject to other terms of the agreement. Shionogi has also granted to the Company certain rights to co-promote zuranolone in Japan. The Company maintains exclusive rights to develop and commercialize zuranolone outside of Japan, Taiwan and South Korea. The upfront cash payment and any payments for milestones and royalties are non-refundable and non-creditable. Due to the uncertainty of pharmaceutical development and the high historical failure rates generally associated with drug development, the Company may not receive any milestone payments or any royalty payments from Shionogi. The Company concluded that Shionogi meets the definition to be accounted for as a customer because the Company is delivering intellectual property and know-how rights for the zuranolone program in support of territories in which the parties are not jointly sharing the risks and rewards. In addition, the Company determined that the Shionogi collaboration met the requirements to be accounted for as a contract, including that it was probable that the Company will collect the consideration to which the Company was entitled in exchange for the goods or services that will be delivered to Shionogi. In determining the appropriate amount of revenue to be recognized under Topic 606, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measured the transaction price, including the constraint on variable consideration; (iv) allocated the transaction price to the performance obligations; and (v) recognized revenue when (or as) the Company satisfied each performance obligation. The Company determined that the performance obligations in the contract included the license to zuranolone and the supply of certain materials during the clinical development phase, which includes the supply of active pharmaceutical ingredient (“API”). The performance obligation related to the license to zuranolone was determined to be distinct from other performance obligations and therefore was a separate performance obligation for which control was transferred upon signing. The obligation to provide certain clinical materials, including API for use during the development period, was determined to be a separate performance obligation. Given that Shionogi is not obligated to purchase any minimum amount or quantities of commercial API, t he supply of API to Shionogi for commercial use was determined to be an option for Shionogi, rather than a performance obligation of the Company at contract inception and will be accounted for if and when exercised. The Company also determined that there was no separate material right in connection with the supply of API for commercial use as the expected pricing was not at a discount . Given this fact pattern, the Company has concluded the agreement has two performance obligations. Under the clinical supply agreement, the Company will manufacture and supply to Shionogi (i) clinical quantities of API reasonably required by Shionogi for the development of licensed products in the Shionogi territory under the collaboration and license agreement and (ii) quantities of drug product reasonably required for use by Shionogi in Phase 1 studies of zuranolone in the Shionogi territory under the collaboration and license agreement, in the quantities agreed to by the parties. Collaboration revenue from the clinical supply agreement, which excludes the $90.0 million upfront payment, pertains to the clinical material sold under the terms of the clinical supply agreement. The Company records the costs related to the clinical supply agreement in research and development expense on its condensed consolidated statements of operations and comprehensive loss. The Company completed the evaluation of the standalone selling prices of each of the performance obligations and determined that the standalone selling price of the license performance obligation was $90.0 million. The Company recognized the transaction price allocated to the license performance obligation of $90.0 million as revenue during the quarter upon delivery of the license to Shionogi and resulting ability of Shionogi to use and benefit from the license, which was in the three months ended June 30, 2018. The remaining transaction price related to the performance obligation for the supply of certain clinical material is not significant. The potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the probability of achievement. The Company will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, adjust its estimate of the transaction price.

Sale of Equity Securities

Sale of Equity Securities	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Sale of Equity Securities	7. Sale of Equity Securities On February 27, 2019, the Company completed the sale of 3,833,334 shares of its common stock in a follow-on underwritten public offering at a price to the public of $150.00 per share, resulting in net proceeds of $560.9 million after deducting commissions and underwriting discounts and offering costs paid by the Company.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation Equity Plans On July 2, 2014, the stockholders of the Company approved the 2014 Stock Option and Incentive Plan (the “2014 Plan”), which became effective immediately prior to the completion of the Company’s IPO. The 2014 Plan provides for the grant of restricted stock awards, restricted stock units, incentive stock options and non-statutory stock options. The 2014 Plan replaced the Company’s 2011 Stock Option and Grant Plan (the “2011 Plan”). The Company no longer grants stock options or other awards under its 2011 Plan, but any options outstanding under the 2011 Plan remain outstanding and effective in accordance with their terms. The 2014 Plan provides for an annual increase, to be added on the first day of each fiscal year, by up to 4% of the Company’s outstanding shares of common stock as of the last day of the prior year. On January 1, 2020, 2,075,087 shares of common stock, representing 4% of the Company’s outstanding shares of common stock as of December 31, 2019, were added to the 2014 Plan. On December 15, 2016, the Board of Directors of the Company (the “Board”) approved the 2016 Inducement Equity Plan (as amended and restated, the “2016 Plan”). The 2016 Plan provides for the grant of equity awards to individuals who have not previously been an employee or a non-employee director of the Company to induce them to accept employment and to provide them with a proprietary interest in the Company. On September 20, 2018, the Board amended the 2016 Plan to increase the total number of shares reserved for issuance by 1,200,000 shares. As of September 30, 2020, the total number of shares reserved under all equity plans was 12,580,983 and the total number of shares available for future issuance under all equity plans was 4,264,646 shares Restricted Stock Units The table below summarizes activity relating to time-based restricted stock units and performance restricted stock units: Shares Outstanding as of December 31, 2019 333,243 Granted 995,506 Vested — Forfeited (341,753 ) Outstanding as of September 30, 2020 986,996 During the three months ended March 31, 2017, the Company granted 32,500 time-based restricted stock units to certain employees of the Company. The Company did not grant time-based restricted stock units prior to January 1, 2017. These time-based restricted stock units vested ratably over two years, with vesting of 50% at both the one-year and two-year anniversary of the grant date, which was in February 2018 and February 2019, respectively. The fair value of the time-based restricted stock units that vested during the nine months ended September 30, 2019 was $2.0 million. No time-based restricted stock units vested during the three and nine months ended September 30, 2020 and the three months ended September 30, 2019. During the nine months ended September 30, 2020, the Company granted 550,890 time-based restricted stock units to certain employees of the Company. These time-based restricted stock units will vest over two years, with 25% vesting at the one-year anniversary of the grant date and 75% vesting at the two-year anniversary of the grant date, which will be in April 2021 and April 2022, respectively. During the three months ended September 30, 2020, the Company granted no time-based restricted stock units. During the year ended December 31, 2018, the Company granted 37,800 performance restricted stock units that will vest upon the achievement of a certain commercial milestone. During the three months ended September 30, 2020 and 2019, the Company granted to employees of the Company 11,800 and 16,258 performance restricted stock units, respectively; and during the nine months ended September 30, 2020 and 2019, the Company granted 444,616 and 386,714 performance restricted stock units, respectively. These performance restricted stock units are related to the achievement of certain clinical and regulatory development milestones related to product candidates and commercial milestones. Recognition of stock-based compensation expense associated with performance restricted stock units commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones. During the three months ended September 30, 2019, one milestone for a performance restricted stock unit was achieved. This milestone represents 18% of the performance restricted stock units that were granted during the nine months ended September 30, 2019. The fair value of the performance restricted stock units that vested during the three and nine months ended September 30, 2019 was $11.1 million. No performance restricted stock units vested during the three and nine months ended September 30, 2020. At September 30, 2020, 986,996 restricted stock units were both outstanding and unvested, and the total unrecognized stock-based compensation expense related to those awards was $61.4 million. Option Rollforward The table below summarizes activity related to time-based and performance-based stock options: Shares Weighted Average Exercise Price Weighted Average Remaining Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2019 8,163,113 $ 106.30 7.75 $ 87,972 Granted 1,443,795 $ 55.23 Exercised (72,916 ) $ 39.91 Forfeited (2,204,651 ) $ 120.69 Outstanding as of September 30, 2020 7,329,341 $ 92.58 7.14 $ 69,947 Exercisable as of September 30, 2020 4,500,068 $ 88.63 6.25 $ 53,983 At September 30, 2020, the Company had unrecognized stock-based compensation expense related to its unvested service-based stock option awards of $143.3 million, which is expected to be recognized over the remaining weighted average vesting period of 1.83 years. The intrinsic value of stock options exercised during the nine months ended September 30, 2020 and 2019 was $0.9 million and $115.2 million, respectively. Performance-Based Stock Options Since January 1, 2019, the Company granted no options to employees to purchase shares of common stock that contain performance-based vesting criteria. During the three months ended March 31, 2019, the achievement of one unmet commercial milestone that was the criteria for vesting of performance-based stock options was considered probable, and therefore $14.2 million of stock-based compensation expense was recognized related to these awards for the three months ended March 31, 2019. During the three months ended June 30, 2019, this commercial milestone was achieved. Stock options with this milestone were granted during the years ended December 31, 2018 and 2017. This milestone represents 20% and 33% of the performance-based option grants that were made during the years ended December 31, 2018 and 2017, respectively. During the three months ended June 30, 2019, the Company recognized stock-based compensation expense related to this milestone of $2.1 million. During the nine months ended September 30, 2019, the Company recognized stock-based compensation expense related to this milestone of $16.3 million. As of September 30, 2020 and 2019, for performance-based option grants that were outstanding, the achievement of the milestones that had not been met that are the criteria for vesting of performance-based stock options was considered not probable, and therefore no expense has been recognized related to these awards in the nine months ended September 30, 2020 and 2019. As of September 30, 2020, 383,906 performance-based stock options were both outstanding and unvested, and the total unrecognized stock-based compensation expense related to those awards was $29.0 million. Stock-Based Compensation Expense Stock-based compensation expense recognized during the three and nine months ended September 30, 2020 and 2019 was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Research and development $ 9,927 $ 17,111 $ 32,270 $ 51,528 Selling, general and administrative 10,181 26,558 41,192 71,024 Restructuring — — 1,788 — $ 20,108 $ 43,669 $ 75,250 $ 122,552 Stock-based compensation expense recognized during the three and nine months ended September 30, 2020 and 2019 by award type was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Stock options $ 18,797 $ 32,119 $ 72,434 $ 109,963 Restricted stock units 1,066 10,934 1,815 10,992 Employee stock purchase plan 245 616 1,001 1,597 $ 20,108 $ 43,669 $ 75,250 $ 122,552 The stock-based compensation expense recorded for the restructuring in the nine months ended September 30, 2020 is the incremental amount related to modifying the exercise period for outstanding, vested option grants that had been made to employees who were terminated in the restructuring. The weighted average grant date fair value per share of stock options granted under the Company’s stock option plans during the nine months ended September 30, 2020 and 2019 was $37.04 and $99.49, respectively.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	9. Net Loss Per Share Basic and diluted net loss per share was calculated as follows for the three and nine months ended September 30, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Basic net loss per share: Numerator: Net loss (in thousands) $ (105,735 ) $ (179,958 ) $ (368,822 ) $ (511,585 ) Denominator: Weighted average common stock outstanding —basic 51,981,468 51,704,687 51,938,923 50,496,489 Dilutive effect of shares of common stock equivalents resulting from common stock options and restricted stock units — — — — Weighted average common stock outstanding —diluted 51,981,468 51,704,687 51,938,923 50,496,489 Net loss per share—basic and diluted $ (2.03 ) $ (3.48 ) $ (7.10 ) $ (10.13 ) The following common stock equivalents outstanding as of September 30, 2020 and 2019 were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock options 6,945,435 7,085,322 6,945,435 7,085,322 Restricted stock units 489,495 — 489,495 — Employee stock purchase plan 16,396 10,900 16,396 10,900 7,451,326 7,096,222 7,451,326 7,096,222 Stock options and restricted stock units that are outstanding and contain performance-based vesting criteria for which the performance conditions have not been met are excluded from the calculation of common stock equivalents outstanding.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2020
Restructuring And Related Activities [Abstract]
Restructuring	10. Restructuring In April 2020, the Company announced a restructuring plan to enable the Company to advance its corporate strategy and pipeline that included the elimination of approximately 53% of the Company’s workforce. The workforce reduction primarily affected the ZULRESSO commercial operation and related selling, general and administrative support functions. In the nine months ended September 30, 2020, the Company recorded $27.9 million of expense, primarily for one-time termination benefits to the affected employees, primarily for cash payments of severance, healthcare benefits and outplacement assistance. The Company expects that substantially all of the accrued restructuring charges as of September 30, 2020 will be paid in cash by the end of 2020. Restructuring activity during the nine months ended September 30, 2020 was as follows: Restructuring accrual (in thousands) Balance as of January 1, 2020 $ - Restructuring expenses incurred 27,873 Cash paid (24,079 ) Non-cash activity (2,438 ) Balance as of September 30, 2020 $ 1,356

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. The condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of the Company’s management, the accompanying condensed consolidated financial statements contain all adjustments, consisting of only normal recurring adjustments, necessary for a fair statement of its financial position as of September 30, 2020, its results of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, its cash flows for the nine months ended September 30, 2020 and 2019, and its statements of changes in stockholders’ equity for the three and nine months ended September 30, 2020 and 2019. The consolidated balance sheet at December 31, 2019 was derived from audited financial statements, but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results for the year ending December 31, 2020, or for any future period.
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies, within the “Notes to Consolidated Financial Statements” accompanying its Annual Report on Form 10-K for the fiscal year ended December 31, 2019. Intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including sales, expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including developments related to the scope and duration of the pandemic; the timing, extent and frequency of surges in the number of cases of COVID-19; new information that may emerge concerning COVID-19; and the actions taken to contain the COVID-19 pandemic. The Company has made estimates of the impact of the COVID-19 pandemic within its consolidated financial statements, and there may be changes to those estimates in future periods.
Research and Development Costs and Accruals	Research and Development Costs and Accruals Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, depreciation, contract services and other related costs. Research and development costs are expensed to operations as the related obligation is incurred. The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the U.S. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of the end of the reporting period
Stock-Based Compensation	Stock-Based Compensation The Company recognizes compensation expense for stock-based awards, including grants of stock options and restricted stock units, made to employees and non-employee directors based on the estimated fair value on the date of grant, over the requisite service period. The Company recognizes stock-based compensation expense for only the portion of awards that are expected to vest. For awards that vest upon achievement of a performance condition, the Company recognizes compensation expense when achievement of the performance condition is met or during the period from which meeting the condition is deemed probable until the expected date of meeting the performance condition. The fair value of each option grant is estimated using the Black-Scholes option-pricing model. Through December 31, 2015, the Company lacked sufficient Company-specific historical and implied volatility information, and as a result, the Company used the volatility of a group of publicly-traded peer companies in the Black-Scholes calculations. Beginning in 2016, the Company estimated its expected volatility using a weighted average of the historical volatility of publicly-traded peer companies and the volatility of its common stock and expected to continue to do so until such time as it has adequate historical data regarding the volatility of its common stock price for the duration of the expected term. Effective January 1, 2020, the Company began using the historical volatility of only its common stock, as there is adequate historical data for the duration of the expected term. The expected term of the options granted to employees and non-employee directors by the Company has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. Through December 31, 2018, the expected term of the options granted to non-employee consultants was determined based on the contractual term of the options, and since January 1, 2019, the “simplified” method has been used. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The Company also applies a forfeiture rate in order to calculate stock-based compensation expense. Expected forfeitures are based on the historical experience of the Company and management’s expectations of future forfeitures. To the extent actual forfeitures differ from the estimates, the difference is recorded as a cumulative adjustment in the period in which the estimates are revised.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the date of purchase to be cash equivalents. As of September 30, 2020, cash equivalents were comprised of money market funds. As of December 31, 2019, cash equivalents were comprised of commercial paper and money market funds.
Marketable Securities	Marketable securities Marketable securities consist of investments with original maturities greater than 90 days. The Company has classified its investments with maturities beyond one year as short-term, based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. The Company considers its investment portfolio of marketable securities to be available-for-sale. Accordingly, these investments are recorded at fair value, which is based on quoted market prices. Unrealized gains and losses are reported as the accumulated other comprehensive items in stockholders’ equity. When the fair value is below the amortized cost of the asset, an estimate of expected credit losses is made. The credit-related impairment amount is recognized in net income; the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in net income.
Fair Value Measurements	Fair Value Measurements Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three categories: Level 1 — Quoted market prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s cash equivalents and marketable securities at September 30, 2020 and December 31, 2019 were carried at fair value, determined according to the fair value hierarchy; see Note 3, Fair Value Measurements. The carrying amounts reflected in the condensed consolidated balance sheets for accounts payable and accrued expenses approximate their fair values due to their short-term maturities at September 30, 2020 and December 31, 2019, respectively.
Revenue Recognition	Revenue Recognition The Company received approval of ZULRESSO from the FDA in March 2019 and subsequently began to record revenues from product sales in June 2019. Prior to the second quarter of 2019, all of the revenues of the Company were derived from the Company’s collaboration agreement and supply agreement with Shionogi & Co., Ltd. (“Shionogi”). The terms of the Company’s collaboration agreement include consideration such as non-refundable license fees, reimbursement of any development costs the Company incurs on behalf of Shionogi, payments due upon the achievement, if any, of clinical and pre-clinical performance-based development milestones, regulatory milestones, and sales-based milestones and royalties on product sales, if development is successful in the Shionogi territory, as well as payments for the supply of active pharmaceutical ingredient (“API”) and drug product for clinical trials. To date, revenue from the Company’s collaboration agreement with Shionogi has come from an initial, upfront license fee upon execution of the agreement and from the supply of API for Shionogi’s clinical trials. Under Accounting Standards Codification (“ASC”) Topic 606, “ Revenue from Contracts with Customers Product revenue The Company recognizes product revenues, net of variable consideration related to certain allowances and accruals that are determined using the expected value method, in its condensed consolidated financial statements at the point in time when control transfers to the customer, which is typically when the product has been delivered to the customer’s location. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. The Company’s only performance obligation identified for ZULRESSO is to deliver the product to the location specified by the customer’s order. The Company records shipping and handling costs associated with delivery of product to its customers within selling, general and administrative expenses on its condensed consolidated statements of operations and comprehensive loss. The Company expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset would be less than one year. If the Company were to incur incremental costs with an amortization period greater than a year, such costs would be capitalized as contract assets, as they are expected to be recovered, and would be expensed by amortizing on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. The Company did not have any contract assets (unbilled receivables) at September 30, 2020, as customer invoicing generally occurs before or at the time of revenue recognition. The Company did not have any contract liabilities at September 30, 2020, as the Company did not receive any payments in advance of satisfying its performance obligations to its customers. Amounts billed or invoiced are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. The Company records reserves, based on contractual terms, for components of variable consideration related to product sold during the reporting period, as well as its estimate of product that remains in the distribution channel inventory of its customers at the end of the reporting period. On a quarterly basis, the Company updates its estimates and records any necessary material adjustments in the period they are identified.
Inventory	Inventory Inventory is stated at the lower of cost or estimated net realizable value with cost determined on a first-in, first-out basis. Inventory costs include raw materials, third-party contract manufacturing, third-party packaging services, and freight. Raw and intermediate materials that may be utilized for either research and development or commercial purposes are identical and, as a result, are both classified as inventory. Amounts in inventory associated with research and development are charged to research and development expense when the product enters the research and development process and can no longer be used for commercial purposes and, therefore, does not have an “alternative future use” as defined in authoritative guidance. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period and writes down any excess and obsolete inventory to its estimated net realizable value in the period it is identified. If they occur, such impairment charges are recorded as a component of cost of goods sold in the condensed consolidated statements of operations and comprehensive loss. Inventory is included in prepaid expenses and other current assets on the condensed consolidated balance sheets and the amount was not significant as of September 30, 2020. Prior to the initial date regulatory approval is received, costs related to the production of inventory are recorded as research and development expense on the Company’s condensed consolidated statements of operations and comprehensive loss in the period incurred. The Company received FDA approval for ZULRESSO on March 19, 2019 and subsequently began capitalizing costs related to inventory manufacturing.
Cost of Goods Sold	Cost of Goods Sold Cost of goods sold includes direct and indirect costs related to the manufacturing and distribution of ZULRESSO, including third-party manufacturing costs, packaging services, freight, third-party royalties payable on the Company’s net product revenues and amortization of intangible assets associated with ZULRESSO. Cost of goods sold may also include period costs related to certain inventory manufacturing services, inventory adjustment charges, as well as manufacturing variances. In connection with the FDA approval of ZULRESSO on March 19, 2019, the Company subsequently began capitalizing inventory manufactured or purchased after this date. As a result, certain manufacturing costs associated with product shipments of ZULRESSO were expensed prior to FDA approval and, therefore, are not included in cost of goods sold during the three and nine months ended September 30, 2020 and 2019.
Accounts Receivable	Accounts Receivable The Company’s trade accounts receivable consist of amounts due from specialty distributors, specialty pharmacies and medically-supervised healthcare settings that have been certified under a Risk Evaluation and Mitigation Strategy (“REMS”) program in the U.S. related to sales of ZULRESSO and have standard payment terms that generally require payment within 30 to 90 days from the invoice date. The Company monitors the financial performance and creditworthiness of customers so that it can properly assess and respond to changes in their credit profile. The Company reserves against trade accounts receivable for estimated losses that may arise from a customer’s inability to pay and any amounts determined to be uncollectible are written off against the reserve when it is probable that the receivable will not be collected. Trade accounts receivable are included in prepaid expenses and other current assets on the condensed consolidated balance sheets. As of September 30, 2020, the Company has not provided any allowance for bad debts against the trade accounts receivable, and the amount of trade accounts receivable was not significant.
Leases	Leases The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term, and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit interest rate when readily determinable and uses the Company’s incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The lease payments used to determine the Company’s operating lease assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation, when determinable, and are recognized in the Company’s operating lease assets in the Company’s condensed consolidated balance sheets. In addition, the Company’s contracts contain lease and non-lease components. The Company combines lease and non-lease components, which are accounted for together as lease components. The Company’s operating leases are reflected in the right-of-use operating asset; operating lease liability, current portion; and operating lease liability, net of current portion in the Company’s condensed consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Short-term leases, defined as leases that have a lease term of 12 months or less at the commencement date, are excluded from this treatment and are recognized on a straight-line basis over the term of the lease. Variable lease payments are the amounts owed by the Company to a lessor that are not fixed, such as reimbursement for common area maintenance and utilities costs for facility leases and maintenance and tolls for leased vehicles. Variable lease payments are expensed when incurred.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (Topic 842) Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements Narrow-Scope Improvement for Lessors Leases (Topic 842): Codification Improvements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . This standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. For available-for-sale debt securities, entities are required to recognize an allowance for credit losses rather than a reduction in carrying value of the asset. Entities are no longer permitted to consider the length of time that fair value has been less than amortized cost when evaluating when credit losses should be recognized. The Company adopted the standard on the required effective date of January 1, 2020, on a prospective basis. This guidance did not have a significant impact on the Company’s condensed consolidated financial statements and related disclosures . In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement The Company adopted the standard on the required effective date of January 1, 2020. This guidance did not have a significant impact on the Company’s condensed consolidated financial statements and related disclosures In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s condensed consolidated financial statements upon adoption.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Summary of Company's Cash Equivalents and Marketable Securities	The following tables summarize the Company’s cash equivalents and marketable securities as of September 30, 2020 and December 31, 2019. September 30, 2020 Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (in thousands) Cash equivalents: Cash equivalents $ 184,270 $ 184,270 $ — $ — Total cash equivalents 184,270 184,270 — — Marketable securities: U.S. government securities 172,742 — 172,742 — U.S. corporate bonds 174,964 — 174,964 — International corporate bonds 65,682 — 65,682 — U.S. commercial paper 40,947 — 40,947 — International commercial paper 29,932 — 29,932 — Total marketable securities 484,267 — 484,267 — $ 668,537 $ 184,270 $ 484,267 $ — December 31, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (in thousands) Cash equivalents: Cash equivalents $ 126,705 $ 65,414 $ 61,291 $ — Total cash equivalents 126,705 65,414 61,291 — Marketable securities: U.S. government securities 205,328 — 205,328 — U.S. corporate bonds 429,845 — 429,845 — International corporate bonds 142,998 — 142,998 — U.S. commercial paper 52,261 — 52,261 — International commercial paper 51,256 — 51,256 — Total marketable securities 881,688 — 881,688 — $ 1,008,393 $ 65,414 $ 942,979 $ —
Summary of Gross Unrealized Gains and Losses of Marketable Securities	The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of September 30, 2020 and December 31, 2019: September 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Credit Losses Fair Value (in thousands) Assets: U.S. government securities $ 172,685 $ 72 $ (15 ) $ — $ 172,742 U.S. corporate bonds 174,465 514 (15 ) — 174,964 International corporate bonds 65,291 391 — — 65,682 U.S. commercial paper 40,948 1 (2 ) — 40,947 International commercial paper 29,932 — — — 29,932 $ 483,321 $ 978 $ (32 ) $ — $ 484,267 December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) Assets: U.S. government securities $ 205,172 $ 176 $ (20 ) $ 205,328 U.S. corporate bonds 429,148 797 (100 ) 429,845 International corporate bonds 142,568 457 (27 ) 142,998 U.S. commercial paper 52,252 14 (5 ) 52,261 International commercial paper 51,253 5 (2 ) 51,256 $ 880,393 $ 1,449 $ (154 ) $ 881,688

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net, consists of the following: September 30, December 31, 2020 2019 (in thousands) Computer hardware and software $ 2,758 $ 2,830 Furniture and equipment 1,865 1,828 Leasehold improvements 9,220 8,967 13,843 13,625 Less: Accumulated depreciation (6,439 ) (4,499 ) $ 7,404 $ 9,126
Summary of Accrued Expenses	Accrued expenses consist of the following: September 30, December 31, 2020 2019 (in thousands) Accrued research and development costs $ 29,233 $ 46,940 Restructuring 1,356 - Employee-related 9,147 22,011 Professional services 6,045 16,720 Other 975 947 $ 46,756 $ 86,618

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Activity Relating to Restricted Stock Units	The table below summarizes activity relating to time-based restricted stock units and performance restricted stock units: Shares Outstanding as of December 31, 2019 333,243 Granted 995,506 Vested — Forfeited (341,753 ) Outstanding as of September 30, 2020 986,996
Summary of Activity Relating to Time Based and Performance Based Stock Options	The table below summarizes activity related to time-based and performance-based stock options: Shares Weighted Average Exercise Price Weighted Average Remaining Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2019 8,163,113 $ 106.30 7.75 $ 87,972 Granted 1,443,795 $ 55.23 Exercised (72,916 ) $ 39.91 Forfeited (2,204,651 ) $ 120.69 Outstanding as of September 30, 2020 7,329,341 $ 92.58 7.14 $ 69,947 Exercisable as of September 30, 2020 4,500,068 $ 88.63 6.25 $ 53,983
Summary of Stock-Based Compensation Expense Recognized	Stock-based compensation expense recognized during the three and nine months ended September 30, 2020 and 2019 was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Research and development $ 9,927 $ 17,111 $ 32,270 $ 51,528 Selling, general and administrative 10,181 26,558 41,192 71,024 Restructuring — — 1,788 — $ 20,108 $ 43,669 $ 75,250 $ 122,552
Summary of Stock-Based Compensation Expense by Award Type Recognized	Stock-based compensation expense recognized during the three and nine months ended September 30, 2020 and 2019 by award type was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Stock options $ 18,797 $ 32,119 $ 72,434 $ 109,963 Restricted stock units 1,066 10,934 1,815 10,992 Employee stock purchase plan 245 616 1,001 1,597 $ 20,108 $ 43,669 $ 75,250 $ 122,552

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share was calculated as follows for the three and nine months ended September 30, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Basic net loss per share: Numerator: Net loss (in thousands) $ (105,735 ) $ (179,958 ) $ (368,822 ) $ (511,585 ) Denominator: Weighted average common stock outstanding —basic 51,981,468 51,704,687 51,938,923 50,496,489 Dilutive effect of shares of common stock equivalents resulting from common stock options and restricted stock units — — — — Weighted average common stock outstanding —diluted 51,981,468 51,704,687 51,938,923 50,496,489 Net loss per share—basic and diluted $ (2.03 ) $ (3.48 ) $ (7.10 ) $ (10.13 )
Summary of Anti-Dilutive Common Stock Equivalents Outstanding	The following common stock equivalents outstanding as of September 30, 2020 and 2019 were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock options 6,945,435 7,085,322 6,945,435 7,085,322 Restricted stock units 489,495 — 489,495 — Employee stock purchase plan 16,396 10,900 16,396 10,900 7,451,326 7,096,222 7,451,326 7,096,222

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2020
Restructuring And Related Activities [Abstract]
Summary of Restructuring Activity	The Company expects that substantially all of the accrued restructuring charges as of September 30, 2020 will be paid in cash by the end of 2020. Restructuring activity during the nine months ended September 30, 2020 was as follows: Restructuring accrual (in thousands) Balance as of January 1, 2020 $ - Restructuring expenses incurred 27,873 Cash paid (24,079 ) Non-cash activity (2,438 ) Balance as of September 30, 2020 $ 1,356

Nature of the Business - Additi

Nature of the Business - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Nature Of Business [Line Items]
Accumulated deficit	$ 2,012,389	$ 1,643,567
Redeemable Convertible Preferred Stock [Member] | Convertible Notes [Member] | Initial Public Offering [Member]
Nature Of Business [Line Items]
Net proceeds from sale of equity and notes	$ 2,200,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Jan. 01, 2019
ASC Topic 842 [Member]
Summary Of Significant Accounting Policies [Line Items]
Lease liabilities		$ 44.2
Right-of-use assets		$ 41.1
Product Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Incremental costs incurred expected amortization period of asset	true

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Company's Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	$ 184,270	$ 126,705
Total marketable securities	484,267	881,688
Total cash equivalents and marketable securities	668,537	1,008,393
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	184,270	126,705
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	184,270	65,414
Total cash equivalents and marketable securities	184,270	65,414
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	184,270	65,414
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents		61,291
Total marketable securities	484,267	881,688
Total cash equivalents and marketable securities	484,267	942,979
Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents		61,291
U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	172,742	205,328
U.S. Government Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	172,742	205,328
U.S. Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	174,964	429,845
U.S. Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	174,964	429,845
International Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	65,682	142,998
International Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	65,682	142,998
U.S. Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	40,947	52,261
U.S. Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	40,947	52,261
International Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	29,932	51,256
International Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	$ 29,932	$ 51,256

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Debt Instrument Fair Value Carrying Value [Line Items]
Transfers among the Level 1, Level 2 and Level 3 categories	$ 0		$ 0
Marketable securities fair value held to maturity	18,900,000	$ 137,100,000
Impairment of assets	0	$ 0
U.S. Corporate Bonds [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities loss on fair value held to maturity	$ 4,000,000
Maximum [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities, remaining contractual maturities	1 year	1 year
Marketable securities held, matuirity period	2 years	2 years
Minimum [Member]
Debt Instrument Fair Value Carrying Value [Line Items]
Marketable securities held, matuirity period	1 year	1 year

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Gross Unrealized Gains and Losses of Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 483,321	$ 880,393
Gross Unrealized Gains	978	1,449
Gross Unrealized Losses	(32)	(154)
Fair Value	484,267	881,688
U.S. Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	172,685	205,172
Gross Unrealized Gains	72	176
Gross Unrealized Losses	(15)	(20)
Fair Value	172,742	205,328
U.S. Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	174,465	429,148
Gross Unrealized Gains	514	797
Gross Unrealized Losses	(15)	(100)
Fair Value	174,964	429,845
International Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	65,291	142,568
Gross Unrealized Gains	391	457
Gross Unrealized Losses		(27)
Fair Value	65,682	142,998
U.S. Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,948	52,252
Gross Unrealized Gains	1	14
Gross Unrealized Losses	(2)	(5)
Fair Value	40,947	52,261
International Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,932	51,253
Gross Unrealized Gains		5
Gross Unrealized Losses		(2)
Fair Value	$ 29,932	$ 51,256

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 13,843	$ 13,625
Less: Accumulated depreciation	(6,439)	(4,499)
Property and equipment, net	7,404	9,126
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,758	2,830
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,865	1,828
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 9,220	$ 8,967

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 700	$ 700	$ 1,981	$ 1,618
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			3 years
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			5 years

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued research and development costs	$ 29,233	$ 46,940
Restructuring	1,356
Employee-related	9,147	22,011
Professional services	6,045	16,720
Other	975	947
Total accrued expenses	$ 46,756	$ 86,618

Leases, Commitments and Conti_2

Leases, Commitments and Contingencies - Operating Leases - Additional Information (Detail) $ in Thousands	Feb. 28, 2019ft²	Jan. 01, 2019USD ($)ft²	Mar. 31, 2019ft²	Dec. 31, 2018ft²	May 31, 2018ft²	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	May 31, 2020USD ($)
Commitments And Contingencies [Line Items]
Lease expire date							Jan. 31, 2022
Operating lease option to extend						true
Operating lease renewal term						5 years
Right-of-use operating asset | $		$ 5,300				$ 26,546	$ 33,771
Operating lease term of contract							3 years
Remaining operating lease asset | $								$ 2,300
Operating Lease One [Member]
Commitments And Contingencies [Line Items]
Office space rent under operating lease	58,442	58,442	63,017
Lease expire date		Aug. 15, 2024	Aug. 31, 2024
Increased office space rent			4,575
Operating Lease Two [Member]
Commitments And Contingencies [Line Items]
Office space rent under operating lease		40,419
Lease expire date		Aug. 31, 2024
Operating Lease Three [Member]
Commitments And Contingencies [Line Items]
Office space rent under operating lease					15,525
Lease expire date					Nov. 30, 2024
Operating Lease Five [Member]
Commitments And Contingencies [Line Items]
Office space rent under operating lease				15,975
Lease expire date				Feb. 29, 2024
Minimum [Member]
Commitments And Contingencies [Line Items]
Operating lease remaining lease terms						1 year
Maximum [Member]
Commitments And Contingencies [Line Items]
Operating lease remaining lease terms						6 years

Leases, Commitments and Conti_3

Leases, Commitments and Contingencies - CyDex License Agreement - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Commitments And Contingencies [Line Items]
Research and development expense	$ 74,078,000	$ 102,108,000	$ 211,008,000	$ 277,565,000
CyDex License Agreement [Member]
Commitments And Contingencies [Line Items]
Research and development expense			1,000,000
CyDex License Agreement [Member] | First and Second Clinical Development Milestones [Member] | Brexanolone [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	800,000		800,000
CyDex License Agreement [Member] | First and Second Regulatory Milestones [Member] | Brexanolone [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	3,800,000		3,800,000
CyDex License Agreement [Member] | Third and Fourth Clinical Development Milestones [Member] | Brexanolone [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	1,300,000		1,300,000
CyDex License Agreement [Member] | Third and Fourth Regulatory Milestones [Member] | Brexanolone [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	8,500,000		8,500,000
CyDex License Agreement [Member] | Clinical Development [Member] | Brexanolone [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense	0		0
Milestone payments	0		0
Milestone payments related to intangible assets	0		0
CyDex License Agreement [Member] | Clinical Development [Member] | SAGE-689 [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	800,000		800,000
CyDex License Agreement [Member] | Regulatory Milestones [Member] | Brexanolone [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense	0		0
Milestone payments	0		0
Intangible asset related to milestone	3,000,000		3,000,000
Milestone payments related to intangible assets	0		3,000,000
CyDex License Agreement [Member] | Regulatory Milestones [Member] | SAGE-689 [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	1,800,000		1,800,000
CyDex License Agreement [Member] | Clinical Development and Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense			2,300,000
Milestone payments			2,300,000
Intangible asset related to milestone	$ 3,000,000		3,000,000
Milestone payments related to intangible assets			$ 3,000,000

Leases, Commitments and Conti_4

Leases, Commitments and Contingencies - University of California License Agreements - Additional Information (Detail) - University of California License Agreements [Member] - USD ($)	Dec. 31, 2015	Jun. 30, 2015	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2015
Commitments And Contingencies [Line Items]
Upfront payment		$ 50,000
Annual license maintenance fee						$ 15,000
Research and development expense related to milestone expense			$ 0	$ 0
Milestone payments			0	0
After The Effective Date [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum	27 years
After The First Sale [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum	15 years
Clinical Development [Member]
Commitments And Contingencies [Line Items]
Milestone payments	$ 100,000
Milestone outstanding	$ 0
Clinical Development [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Percentage of net sales paid as royalties	1.00%
Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Intangible asset related to milestone					$ 500,000
Milestone payments related to intangible assets					$ 500,000
Regulatory Milestones [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		700,000
Sales Milestones [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		$ 2,000,000
Regulatory and Sales Milestones [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense				300,000
Milestone payments				300,000
Intangible asset related to milestone			$ 500,000	500,000
Milestone payments related to intangible assets				$ 500,000

Leases, Commitments and Conti_5

Leases, Commitments and Contingencies - Washington University License Agreement - Additional Information (Detail) - Washington University License Agreement [Member] - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2013	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2013
Commitments And Contingencies [Line Items]
Upfront non-refundable payment	$ 50,000
Annual license maintenance fee						$ 15,000
Issuance of common stock, shares						47,619
Research and development expense related to issue of common stock obligation						$ 100,000
Research and development expense related to milestone expense		$ 0	$ 0	$ 0	$ 0
Milestone payments		$ 0	$ 0	0	$ 0
Clinical Development [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense				50,000
Milestone payments				$ 50,000
Maximum [Member] | Clinical Development [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	700,000
Maximum [Member] | Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	$ 500,000

Collaboration Agreement - Addit

Collaboration Agreement - Additional Information (Detail) - USD ($)	Jun. 12, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue		$ 1,639,000	$ 3,570,000	$ 5,014,000	$ 4,908,000
Shionogi Collaboration Agreement [Member] | SAGE-217 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement effective date	Jun. 12, 2018
Upfront payment	$ 90,000,000
Average percentage on tiered royalties	20.00%
Standalone selling price of license performance obligation		$ 90,000,000		90,000,000
Revenue				$ 90,000,000
Shionogi Collaboration Agreement [Member] | SAGE-217 [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional milestone payment receivable	$ 485,000,000
Shionogi Collaboration Agreement [Member] | SAGE-217 [Member] | Maximum [Member] | Regulatory Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	70,000,000
Shionogi Collaboration Agreement [Member] | SAGE-217 [Member] | Maximum [Member] | Commercial Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	30,000,000
Shionogi Collaboration Agreement [Member] | SAGE-217 [Member] | Maximum [Member] | Sales Milestones [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments	$ 385,000,000

Sale of Equity Securities - Add

Sale of Equity Securities - Additional Information (Detail) $ / shares in Units, $ in Millions	Feb. 27, 2019USD ($)$ / sharesshares
Equity [Abstract]
Issuance of common stock, shares | shares	3,833,334
Common stock price per share | $ / shares	$ 150
Proceeds from public offering of common stock, net of commissions and underwriting discounts and offering costs | $	$ 560.9

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail)	Jan. 01, 2020shares	Jan. 01, 2019shares	Sep. 30, 2020USD ($)shares	Sep. 30, 2019USD ($)shares	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)Milestone	Mar. 31, 2017shares	Sep. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2019shares	Dec. 31, 2018shares	Dec. 31, 2017	Sep. 20, 2018shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total number of shares reserved			12,580,983					12,580,983
Common stock available for issuance under stock option plan			4,264,646					4,264,646
Restricted stock units granted			0					550,890
Outstanding and unvested restricted stock units			986,996					986,996
Stock-based compensation expense | $			$ 20,108,000	$ 43,669,000				$ 75,250,000	$ 122,552,000
Weighted average grant date fair value per share | $ / shares								$ 37.04	$ 99.49
Milestone Three [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance based grants that were achieved											20.00%	33.00%
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted							32,500	995,506
Share based compensation granted under plan vested period							2 years
Fair value of restricted stock units vested | $			$ 0	0				$ 0	$ 2,000,000
Outstanding and unvested restricted stock units			986,996					986,996		333,243
Stock-based compensation expense | $			$ 1,066,000	10,934,000				$ 1,815,000	10,992,000
Restricted Stock Units [Member] | Restricted Stock Units Vest One Year Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units vesting percentage							50.00%	25.00%
Restricted stock units vesting period month and year							2018-02	2021-04
Restricted Stock Units [Member] | Restricted Stock Units Vest Two Year Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units vesting percentage							50.00%	75.00%
Restricted stock units vesting period month and year							2019-02	2022-04
Performance Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted											37,800
Fair value of restricted stock units vested | $			0	$ 11,100,000				$ 0	$ 11,100,000
Percentage of milestone achieved									18.00%
Total unrecognized stock-based compensation expense | $			$ 61,400,000					$ 61,400,000
Performance Restricted Stock Units [Member] | Commercial Milestones [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted			11,800	16,258				444,616	386,714
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted								1,443,795
Total number of shares reserved			7,329,341					7,329,341		8,163,113
Total unrecognized stock-based compensation expense | $			$ 143,300,000					$ 143,300,000
Weighted average period of unrecognized compensation costs								1 year 9 months 29 days
Intrinsic value of options exercised | $								$ 900,000	$ 115,200,000
Stock-based compensation expense | $			18,797,000	$ 32,119,000				72,434,000	109,963,000
Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted		0
Total unrecognized stock-based compensation expense | $			$ 29,000,000					$ 29,000,000
Number of shares outstanding and unvested stock options			383,906					383,906
Performance-Based Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Milestones not achieved | Milestone						1
Stock-based compensation expense | $						$ 14,200,000		$ 0	0
Performance Milestone [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense | $					$ 2,100,000				$ 16,300,000
2011 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted								0
2014 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares annual increase added to plan	2,075,087
2014 Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of increase on outstanding shares of Common stock										4.00%
2016 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total number of shares reserved for issuance													1,200,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Activity Relating to Time Based Restricted Stock Units and Performance Restricted Stock Units (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Mar. 31, 2017	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, Shares	0		550,890
Outstanding, Shares at ending balance	986,996		986,996
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Shares at beginning balance			333,243
Granted, Shares		32,500	995,506
Forfeited, Shares			(341,753)
Outstanding, Shares at ending balance	986,996		986,996

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Activity Relating to Time Based and Performance Based Stock Options (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ending balance, Outstanding Shares	12,580,983
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Beginning balance, Outstanding Shares	8,163,113
Granted, Shares	1,443,795
Exercised, Shares	(72,916)
Forfeited, Shares	(2,204,651)
Ending balance, Outstanding Shares	7,329,341	8,163,113
Exercisable, Shares	4,500,068
Beginning balance, Outstanding Weighted Average Exercise Price | $ / shares	$ 106.30
Granted, Weighted Average Exercise Price | $ / shares	55.23
Exercised, Weighted Average Exercise Price | $ / shares	39.91
Forfeited, Weighted Average Exercise Price | $ / shares	120.69
Ending balance, Outstanding Weighted Average Exercise Price | $ / shares	92.58	$ 106.30
Exercisable, Weighted Average Exercise Price | $ / shares	$ 88.63
Outstanding, Weighted Average Remaining Life	7 years 1 month 20 days	7 years 9 months
Exercisable, Weighted Average Remaining Life	6 years 3 months
Outstanding, Aggregate Intrinsic Value | $	$ 69,947	$ 87,972
Exercisable, Aggregate Intrinsic Value | $	$ 53,983

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	$ 20,108	$ 43,669	$ 75,250	$ 122,552
Restructuring			1,788
Net stock-based compensation expense	20,108	43,669	75,250	122,552
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	9,927	17,111	32,270	51,528
Selling, General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	$ 10,181	$ 26,558	$ 41,192	$ 71,024

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-Based Compensation Expense by Award Type Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	$ 20,108	$ 43,669	$ 75,250	$ 122,552
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	18,797	32,119	72,434	109,963
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	1,066	10,934	1,815	10,992
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total Stock-based compensation expense	$ 245	$ 616	$ 1,001	$ 1,597

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (105,735)	$ (136,347)	$ (126,740)	$ (179,958)	$ (168,221)	$ (163,406)	$ (368,822)	$ (511,585)
Denominator:
Weighted average common stock outstanding —basic	51,981,468			51,704,687			51,938,923	50,496,489
Dilutive effect of shares of common stock equivalents resulting from common stock options and restricted stock units	0			0			0	0
Weighted average common stock outstanding —diluted	51,981,468			51,704,687			51,938,923	50,496,489
Net loss per share—basic and diluted	$ (2.03)			$ (3.48)			$ (7.10)	$ (10.13)

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Anti-Dilutive Common Stock Equivalents Outstanding (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	7,451,326	7,096,222	7,451,326	7,096,222
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	6,945,435	7,085,322	6,945,435	7,085,322
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	489,495		489,495
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents	16,396	10,900	16,396	10,900

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Apr. 30, 2020	Sep. 30, 2020
Restructuring Cost And Reserve [Line Items]
Operating expenses, workforce reduction, percent	53.00%
Employee Severance
Restructuring Cost And Reserve [Line Items]
Employee severance, benefits, and related costs		$ 27.9

Restructuring - Summary of Rest

Restructuring - Summary of Restructuring Activity (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Restructuring And Related Activities [Abstract]
Restructuring	$ (529)	$ 27,873
Cash paid		(24,079)
Non-cash activity		(2,438)
Balance	$ 1,356	$ 1,356