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Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	$ 913,767	$ 725,227
Short-term investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	670,524	650,913
Short-term investments \| Cash and money market fund
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	112,279	141,714
Short-term investments \| Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	144,472	94,572
Short-term investments \| Securities of government-sponsored entities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	142,773	20,840
Short-term investments \| Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	271,000	393,787
Long-term investments \| Cash and money market fund
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value		1,500
Long-term investments \| Certificates of deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	3,206	3,977
Long-term investments \| Securities of government-sponsored entities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	48,708	64,837
Long-term investments \| Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	250,946	151,191
Long-term investments \| Restricted equity securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	55,868
Investments Including Cash Equivalents And Restricted Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	1,029,252	872,418
Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying Value	115,485	147,191
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	112,279	141,714
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| Cash and money market fund \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	112,279	141,714
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| Cash and money market fund \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis		1,500
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| Certificates of deposit \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3,206	3,977
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Investments Including Cash Equivalents And Restricted Cash \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	115,485	147,191
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Cash and Cash Equivalents \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	115,485	147,191
Significant Other Observable Inputs (Level 2) \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	857,899	725,227
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	558,245	509,199
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Commercial paper \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	144,472	94,572
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Securities of government-sponsored entities \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	142,773	20,840
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Corporate debt securities \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	271,000	393,787
Significant Other Observable Inputs (Level 2) \| Long-term investments \| Securities of government-sponsored entities \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	48,708	64,837
Significant Other Observable Inputs (Level 2) \| Long-term investments \| Corporate debt securities \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	250,946	151,191
Significant Other Observable Inputs (Level 2) \| Investments Including Cash Equivalents And Restricted Cash \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	857,899	$ 725,227
Significant Unobservable Inputs (Level 3) \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	55,868
Significant Unobservable Inputs (Level 3) \| Long-term investments \| Restricted equity securities \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	55,868
Significant Unobservable Inputs (Level 3) \| Investments Including Cash Equivalents And Restricted Cash \| Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	$ 55,868

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 112,279	$ 141,714
Marketable securities	558,245	509,199
Accounts receivable	126,575	57,406
Inventory	17,288	10,864
Other current assets	16,647	18,594
Total current assets	831,034	737,777
Marketable securities	299,654	216,028
Operating lease assets	74,364
Restricted equity securities	55,868
Property and equipment, net	41,914	33,869
Restricted cash	3,206	5,477
Total assets	1,306,040	993,151
Current liabilities:
Accounts payable and accrued liabilities	141,285	86,377
Convertible senior notes	408,807
Other current liabilities	15,195	1,856
Total current liabilities	565,287	88,233
Convertible senior notes	408,807	388,496
Noncurrent operating lease liabilities	86,756
Other long-term liabilities	17,074	35,657
Total liabilities	669,117	512,386
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value; 220,000 shares authorized; issued and outstanding shares were 92,272 and 90,797 at December 31, 2019 and 2018, respectively	92	91
Additional paid-in capital	1,768,118	1,660,361
Accumulated other comprehensive income (loss)	1,413	(1,932)
Accumulated deficit	(1,132,700)	(1,177,755)
Total stockholders’ equity	636,923	480,765
Total liabilities and stockholders’ equity	$ 1,306,040	$ 993,151

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Begining balance at Dec. 31, 2016	$ 314,877	$ 87	$ 1,371,432	$ (318)	$ (1,056,324)
Begining balance (in shares) at Dec. 31, 2016		86,883
Net income (loss)	(142,542)				(142,542)
Unrealized gain (loss) on marketable securities	(1,532)			(1,532)
Share-based compensation expense	42,522		42,522
Issuance of common stock for vested restricted stock units	1	$ 1
Issuance of common stock for vested restricted stock units (in shares)		562
Issuance of common stock for stock option exercises	$ 13,864	$ 1	13,863
Issuance of common stock for stock option exercises (in shares)	1,353	1,349
Equity component of convertible debt, net	$ 144,948		144,948
Ending balance at Dec. 31, 2017	372,138	$ 89	1,572,765	(1,850)	(1,198,866)
Ending balance (in shares) at Dec. 31, 2017		88,794
Net income (loss)	21,111				21,111
Unrealized gain (loss) on marketable securities	(82)			(82)
Share-based compensation expense	58,068		58,068
Issuance of common stock for vested restricted stock units (in shares)		429
Issuance of common stock for stock option exercises	$ 29,530	$ 2	29,528
Issuance of common stock for stock option exercises (in shares)	1,592	1,574
Ending balance at Dec. 31, 2018	$ 480,765	$ 91	1,660,361	(1,932)	(1,177,755)
Ending balance (in shares) at Dec. 31, 2018		90,797
Net income (loss)	37,012				37,012
Unrealized gain (loss) on marketable securities	3,345			3,345
Share-based compensation expense	75,262		75,262
Cumulative-effect adjustment to equity due toadoption of ASU 2016-02 \| ASU 2016-02	8,043				8,043
Issuance of common stock for vested restricted stock units (in shares)		416
Issuance of common stock for stock option exercises	$ 27,313	$ 1	27,312
Issuance of common stock for stock option exercises (in shares)	983	981
Issuance of common stock for employee stockpurchase plan	$ 5,183		5,183
Issuance of common stock for employee stock purchase plan (in shares)		78
Ending balance at Dec. 31, 2019	$ 636,923	$ 92	$ 1,768,118	$ 1,413	$ (1,132,700)
Ending balance (in shares) at Dec. 31, 2019		92,272

Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal income taxes at 21% for 2019 and 2018 and 35% for 2017	$ 9,775	$ 4,587	$ (49,889)
State income tax, net of federal benefit	4,044	361	(4,013)
Tax effect on non-deductible expenses	855	446	433
Branded prescription drug fee	3,707
Share-based compensation expense	(12,785)	(9,778)	(19,589)
Officer compensation	3,068	915	2,163
Change in tax rate	(4,143)	(198)	154,415
Expired tax attributes	1,228	13,874	2,998
Research credits	(10,359)	(13,526)	(5,596)
Change in valuation allowance	13,883	4,306	(79,966)
Other	257	(257)	$ (956)
Income Tax Expense (Benefit), Total	$ 9,530	$ 730

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2019

Text Block [Abstract]

License and Collaboration Agreements

Note 2. License and Collaboration Agreements

AbbVie. In June 2010, we announced an exclusive worldwide collaboration with AbbVie, to develop and commercialize elagolix and all next-generation gonadotropin-releasing factor, or GnRH, antagonists and collectively, GnRH Compounds, for women’s and men’s health. AbbVie made an upfront payment of $75.0 million and has agreed to make additional development and regulatory event-based payments of up to $480.0 million, of which $135.0 million has been earned as of December 31, 2019, and up to an additional $50.0 million in commercial event-based payments.

Under the terms of the agreement, AbbVie is responsible for all third-party development, marketing and commercialization costs. We will be entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights. AbbVie may terminate the collaboration at its discretion upon 180 days’ written notice to us.

We evaluated the terms of this agreement under Topic 606 and determined that there is one performance obligation, the exclusive worldwide license with rights to develop, manufacture and commercialize elagolix. At execution, the transaction price included only

the $75.0 million up-front consideration received. None of the development or regulatory milestones were included in the transaction price, as all milestone amounts were fully constrained. As part of our evaluation of the constraint, we considered numerous factors, including that achievement of the milestones is outside of our control and contingent upon success in future clinical trials and the licensee’s efforts. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as they were determined to relate predominantly to the license granted to AbbVie and therefore have also been excluded from the transaction price. We will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

In the third quarter of 2019, AbbVie submitted a new drug application, or NDA, with the FDA for the approval of elagolix in the treatment of uterine fibroids. The NDA was accepted by the FDA with a Prescription Drug User Fee Act, or PDUFA, target action date in the second quarter of 2020. The FDA’s acceptance of the NDA triggered a milestone payment of $20.0 million, which we recognized as revenue in the third quarter of 2019 and received in the fourth quarter of 2019. On July 24, 2018, AbbVie received approval from the FDA for ORILISSA for the management of moderate to severe endometriosis pain in women, resulting in the achievement of a $40.0 million event-based milestone, which we recognized as revenue in 2018. We also recognized sales-based royalties on AbbVie net sales of ORILISSA of approximately $14.3 million for 2019 and $1.6 million for 2018. In 2017, event-based revenue of $30.0 million was recognized based on AbbVie’s new drug application, or NDA, submission for elagolix in endometriosis being accepted by the FDA.

BIAL – Portela & Ca, S.A. In February 2017, we entered into an exclusive license agreement with BIAL – Portela & Ca, S.A., or BIAL, for the development and commercialization of opicapone for the treatment of human diseases and conditions, including Parkinson’s disease, in the U.S. and Canada. We paid BIAL an upfront license fee of $30.0 million, which was expensed in 2017 as acquired in-process R&D. During the first quarter of 2018, the FDA provided guidance on the regulatory path forward to support an NDA for opicapone for Parkinson’s disease, in which the FDA did not request that we conduct an additional Phase III study, resulting in a $10.0 million event-based milestone payment to BIAL, which was expensed as incurred. In the second quarter of 2019, we submitted an NDA with the FDA for opicapone as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients. The NDA was accepted by the FDA with a PDUFA target action date of April 26, 2020. The FDA’s acceptance of the NDA triggered a milestone payment of $10.0 million, which we expensed as R&D in the second quarter of 2019. We may be required to pay up to an additional $95.0 million in milestone payments associated with the regulatory approval and net sales of opicapone. FDA approval of opicapone for Parkinson’s disease would trigger a milestone payment of $20.0 million, payable by us to BIAL. Upon commercialization of opicapone, we agreed to determine certain annual sales forecasts. In the event we fail to meet the minimum sales requirements for a particular year, we would be required to pay BIAL an amount equal to the difference between the actual net sales and minimum sales requirements for such year. In the event we fail to meet the minimum sales requirements for any two years, BIAL may terminate the agreement.

Under the terms of the agreement, we are responsible for the management and cost of all opicapone development and commercialization activities in the U.S. and Canada. Further, unless terminated earlier, the agreement will continue on a licensed product-by-product and country-by-country basis until a generic product in respect of such licensed product under the agreement is sold in a country and sales of such generic product are greater than a specified percentage of total sales of such licensed product in such country. Upon our written request prior to the estimated expiration of the term in respect of a licensed product, the parties shall negotiate a good faith continuation of BIAL’s supply of such licensed product after the term. After the term, and if BIAL is not supplying a certain licensed product, we shall pay BIAL a trademark royalty based on the net sales of such licensed product. Either party may terminate the agreement earlier if the other party materially breaches the agreement and does not cure the breach within a specified notice period, or upon the other party’s insolvency. BIAL may terminate the agreement if we fail to use commercially reasonable efforts or to submit an NDA for a licensed product by a specified date or under certain circumstances involving a change of control of Neurocrine. In certain circumstances where BIAL elects to terminate the agreement in connection with Neurocrine’s change of control, BIAL shall pay us a termination fee. We may terminate the agreement at any time for any reason upon six months written notice to BIAL if prior to the first NDA approval in the U.S., and upon nine months written notice to BIAL if such notice is given after the first NDA approval in the U.S. If our termination request occurs prior to the first NDA approval in the U.S., we shall pay BIAL a termination fee except under certain conditions specified in the agreement.

Voyager. We entered into a collaboration and license agreement with Voyager, a clinical-stage gene therapy company, which became effective in March 2019. The agreement is focused on the development and commercialization of four programs using Voyager’s proprietary gene therapy platform. The four programs consist of the NBIb-1817 (VY-AADC) program for Parkinson’s disease, the Friedreich’s ataxia program and the rights to two undisclosed programs.

In connection with the agreement, we paid Voyager $115.0 million upfront and purchased $50.0 million of Voyager’s common stock at $11.9625 per share, representing approximately 4.2 million shares. Pursuant to the terms of the agreement, Voyager may also be entitled to an additional $1.7 billion in development, regulatory and commercial milestone payments, as well as royalties on net sales of any collaboration product.

Pursuant to development plans agreed to by us and Voyager, unless Voyager exercises its co-development and co-commercialization rights as provided for in the agreement, we will be responsible for all development costs. Further, upon the occurrence of a specified event for each program, we will assume responsibility for the development, manufacturing, and commercialization activities of such program.

We accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business. Our equity investment in Voyager was recorded at a fair value of $54.7 million after considering Voyager’s stock price on the date of closing and certain lock-up and voting provisions applicable to the acquired shares. The remaining $113.1 million of the purchase price, which

includes the applicable transaction costs, was expensed as in-process research and development, or IPR&D, in the first quarter of 2019.

In June 2019, we entered into an amendment to the collaboration and license agreement with Voyager. Under the terms of the amendment, we paid Voyager $5.0 million upfront to obtain rights outside the United States, or U.S., to the Friedreich’s ataxia program in connection with the early return of those rights to Voyager pursuant to a restructuring of Voyager’s gene therapy relationship with Sanofi Genzyme. The upfront payment was expensed as IPR&D in the second quarter of 2019.

We may terminate the collaboration and license agreement with Voyager upon 180 days’ written notice to Voyager prior to the first commercial sale of any collaboration product or upon one year after the date of notice if such notice is provided after the first commercial sale of any collaboration product. Unless terminated earlier, the agreement will continue in effect until the expiration of the last to expire royalty term with respect to any collaboration product or the last expiration or termination of any exercised co-development and co-commercialization rights by Voyager as provided for in the agreement.

Xenon. In December 2019, we entered into a license and collaboration agreement with Xenon to establish a collaboration under which the parties will identify, research and develop sodium channel inhibitors, including clinical candidate NBI-921352 (XEN901) and three preclinical candidates, which compounds we will have the exclusive right to further develop and commercialize under the terms and conditions set forth in the agreement.

We will be solely responsible, at our sole cost and expense, for all development and manufacturing of the compounds and any pharmaceutical product that contains a compound, subject to Xenon’s right to elect to co-fund the development of one product in a major indication and thus receive a mid-single digit percentage increase in royalties owed on the net sales of such product in the U.S. If Xenon exercises such option, the parties will share equally all reasonable and documented costs and expenses incurred in connection with the development of such product in the applicable indication, except costs and expenses that are solely related to the development of such product for regulatory approval outside the U.S.

In connection with the agreement, we paid Xenon $30.0 million upfront and purchased $20.0 million of Xenon’s common stock at $14.196 per share, representing approximately 1.4 million shares. Pursuant to the terms of the agreement, Xenon may also be entitled to an additional $1.7 billion in development, regulatory and commercial milestone payments, as well as royalties on net sales of any collaboration product.

We accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business. Our equity investment in Xenon was recorded at a fair value of $14.1 million after considering Xenon’s stock price on the date of closing and certain lock-up and voting provisions applicable to the acquired shares. The remaining $36.2 million of the purchase price, which includes the applicable transaction costs, was expensed as IPR&D in the fourth quarter of 2019.

Unless earlier terminated, the term of the license and collaboration agreement will continue on a product-by-product and country-by-country basis until the expiration of the royalty term for such product in such country. Upon the expiration of the royalty term for a particular product and country, the exclusive license granted by Xenon to us with respect to such product and country will become fully-paid, royalty free, perpetual and irrevocable. We may terminate the license and collaboration agreement by providing at least 90 days’ written notice, provided that such unilateral termination will not be effective for certain products until we have used commercially reasonable efforts to complete certain specified clinical studies. Either party may terminate the agreement in the event of a material breach in whole or in part, subject to specified conditions.

Mitsubishi Tanabe Pharma Corporation. During 2015, we entered into a collaboration and license agreement with Mitsubishi Tanabe Pharma Corporation, or MTPC, for the development and commercialization of INGREZZA for movement disorders in Japan and other select Asian markets. MTPC made an up-front license fee of $30.0 million and has agreed to make payments up to $85.0 million in development and commercialization event-based payments, payments for the manufacture of pharmaceutical products and royalties on product sales in select territories in Asia.

Under the terms of the agreement, MTPC is responsible for all third-party development, marketing and commercialization costs in Japan and other select Asian markets and we would be entitled to a percentage of sales of INGREZZA in Japan and other select Asian markets for the longer of ten years or the life of the related patent rights. Further, the collaboration effort between the parties to advance INGREZZA towards commercialization in Japan and other select Asian markets is governed by joint steering and development committees with representatives from both parties. There are no performance, cancellation, termination or refund provisions in the agreement that would have a material financial consequence to us. We do not directly control when event-based payments will be achieved or when royalty payments will begin. MTPC may terminate the agreement at its discretion upon 180 days’ written notice to us. In such event, all INGREZZA product rights for Japan and other select Asian markets would revert to us.

We assessed this arrangement in accordance with Topic 606 and identified the following performance obligations: (i) INGREZZA technology license and existing know-how; and (ii) development activities to initiate a clinical study of INGREZZA for Huntington’s chorea. We have the option to participate on the joint steering committee, but since participation is at our option it was deemed to not be a performance obligation. The option for MTPC to engage us to manufacture and supply pharmaceutical products, not at a discount, was not considered a material right and therefore not a performance obligation. Based on these assessments, we identified the license and the development activities as the only performance obligations at the inception of the agreement, which were both deemed to be distinct.

To evaluate the appropriate transaction price, we determined that the up-front amount constituted the entirety of the consideration to be included in the transaction price and to be allocated to the performance obligations based on our best estimate of their relative stand-alone selling prices. For the license, the stand-alone selling price was calculated using an income approach model and included the following key assumptions: the development timeline, revenue forecast, discount rate and probabilities of technical and regulatory

success. The relative selling price of our development activities to initiate a clinical study of INGREZZA for Huntington’s chorea was based on an assessment of costs to perform the study, based upon a peer company analysis for similar studies. We believe a change in the assumptions used to determine our stand-alone selling price for the license most likely would not have a significant effect on the allocation of consideration received (or receivable) to the performance obligations.

At execution, the transaction price included only the $30.0 million up-front consideration received. None of the development or regulatory milestones have been included in the transaction price, as all milestone amounts were fully constrained. As part of our evaluation of the constraint, we considered numerous factors, including that achievement of the milestones is outside of our control and contingent upon success in future clinical studies and the licensee’s efforts. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as they were determined to relate predominantly to the license granted to MTPC and therefore have also been excluded from the transaction price. We will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. Under the terms of the agreement, any payment we receive is generally non-refundable.

Since inception of the agreement, we have recognized revenue of $20.6 million associated with the delivery of a technology license and existing know-how, and $15.0 million in development event-based payments resulting from MTPC’s initiation of Phase II/III development of INGREZZA in tardive dyskinesia, or TD, in Asia. In 2019, we recognized revenue of $0.9 million in connection with our initiation of the KINECT-HD study in November 2019, a placebo-controlled Phase III study of valbenazine in adult Huntington’s disease patients with chorea. In accordance with our continuing performance obligations, $9.4 million of the $30.0 million up-front payment is being deferred and will be recognized as revenue over the KINECT-HD study period. No revenue was recognized under the MTPC agreement for 2018. In 2017, we recognized $15.0 million in development event-based payments resulting from MTPC’s initiation of Phase II/III development of INGREZZA in TD in Asia.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Note 9. Income Taxes

Components of income tax expense for continuing operations were as follows:

	Year Ended December 31,
(in thousands)	2019		2018			2017
Current:
Federal	$	—	$	(100	)	$	—
State		9,530		830			—
Total income tax expense	$	9,530	$	730		$	—

The provision for income taxes on earnings subject to income taxes differs from the statutory federal rate due to the following:

	December 31,
(in thousands)	2019			2018			2017
Federal income taxes at 21% for 2019 and 2018 and 35% for 2017	$	9,775		$	4,587		$	(49,889	)
State income tax, net of federal benefit		4,044			361			(4,013	)
Tax effect on non-deductible expenses		855			446			433
Branded prescription drug fee		3,707			—			—
Share-based compensation expense		(12,785	)		(9,778	)		(19,589	)
Officer compensation		3,068			915			2,163
Change in tax rate		(4,143	)		(198	)		154,415
Expired tax attributes		1,228			13,874			2,998
Research credits		(10,359	)		(13,526	)		(5,596	)
Change in valuation allowance		13,883			4,306			(79,966	)
Other		257			(257	)		(956	)
	$	9,530		$	730		$	—

Significant components of our deferred tax assets as of December 31, 2019 and 2018 are listed below.

We assess all available positive and negative evidence to estimate whether sufﬁcient future taxable income will be generated to permit use of the existing deferred tax assets. A signiﬁcant piece of objective negative evidence evaluated was the cumulative book loss incurred over the three-year period ended December 31, 2019. Such objective evidence limits the ability to consider other subjective evidence, such as projections for future growth.

On the basis of this analysis, we recorded a valuation allowance of $346.0 million and $335.2 million at December 31, 2019 and 2018, respectively, to offset the net deferred tax asset below as realization of such asset is uncertain. The amount of the deferred tax asset considered realizable, however, could be adjusted if estimates of future taxable income during the carryforward period are increased or if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as our projections for future growth.

	December 31,
(in thousands)	2019			2018
Deferred tax assets:
Net operating losses	$	181,300		$	223,800
Research and development credits		71,900			62,200
Capitalized research and development		28,000			34,800
Share-based compensation expense		22,900			17,300
Operating lease assets		23,300			100
Intangible assets		49,300			9,400
Other		18,500			19,100
Total deferred tax assets		395,200			366,700
Deferred tax liabilities:
Convertible senior notes		(24,100	)		(26,400	)
Operating lease liabilities		(18,200	)		—
Other		(6,900	)		(5,100	)
Total deferred tax liabilities		(49,200	)		(31,500	)
Net of deferred tax assets and liabilities		346,000			335,200
Valuation allowance		(346,000	)		(335,200	)
Net deferred tax assets	$	—		$	—

At December 31, 2019, we had federal and state income tax net operating loss carry forwards of approximately $816.2 million and $359.8 million, respectively. The federal net operating losses will begin to expire in 2024, unless previously utilized.

A portion of the California net operating loss carry forwards expired in 2018. The remaining California net operating losses will begin to expire in 2028 and the net operating losses related to other states will begin to expire in 2026.

In addition, we have federal and California R&D tax credit carry forwards of $73.2 million and $47.5 million, respectively. A portion of the federal R&D tax credit carry forwards expired in 2019. The remaining federal R&D tax credits will continue to expire in 2020, unless previously utilized. The California R&D tax credits carry forward indefinitely.

Additionally, the future utilization of our net operating loss and R&D tax credit carry forwards to offset future taxable income may be subject to annual limitation, pursuant to Internal Revenue Code Sections 382 and 383, as a result of ownership changes that could result in the future. No such ownership changes have occurred through December 31, 2019.

The impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.

Our policy is to recognize interest or penalties related to income tax matters in income tax expense. Interest and penalties related to income tax matters were not material for 2019, 2018 or 2017.

We are subject to taxation in the U.S. and various state jurisdictions. Our tax years for 2001 (federal) and 2008 (California) and forward are subject to examination by federal and state tax authorities due to the carry forward of unutilized net operating losses and R&D tax credits.

A summary of activity related to unrecognized tax benefits follows:

	Year Ended December 31,
(in thousands)	2019			2018			2017
Balance at January 1	$	54,775		$	37,403		$	34,112
Increases related to prior year tax positions		281			6,103			—
Increases related to current year tax positions		9,519			11,726			3,291
Expiration of the statute of limitations for the assessment of taxes		(657	)		(457	)		—
Balance at December 31	$	63,918		$	54,775		$	37,403

We excluded deferred tax assets that are not more-likely-than-not to be sustained under the technical merits of the tax position. Such unrecognized tax benefits totaled $9.5 million for current year tax positions, as reflected in the table above.

At December 31, 2019, we had $57.9 million of unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate, subject to the valuation allowance. We do not expect a significant change in our unrecognized tax benefits in the next twelve months.

Other Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2019

Other Balance Sheet Details [Abstract]

Summary of Inventory

Inventory consisted of the following:

	December 31,
(in thousands)	2019		2018
Raw materials	$	14,148	$	7,855
Work in process		1,470		2,208
Finished goods		1,670		801
Total inventory	$	17,288	$	10,864

Property and Equipment

Property and equipment, net, consisted of the following:

	December 31,
(in thousands)	2019			2018
Tenant improvements	$	26,342		$	19,857
Scientific equipment		33,483			28,163
Computer equipment		12,460			11,152
Furniture and fixtures		3,188			2,968
blank		75,473			62,140
Less accumulated depreciation		(33,559	)		(28,271	)
Total property and equipment, net	$	41,914		$	33,869

Accounts Payable and Accrued Liabilities

Accounts payable and accrued liabilities consisted of the following:

	December 31,
(in thousands)	2019		2018
Accrued employee related costs	$	38,941	$	27,341
Revenue-related reserves for discounts and allowances		30,634		13,586
Accrued development costs		25,496		7,069
Accounts payable and other accrued liabilities		46,214		38,381
Total accounts payable and accrued liabilities	$	141,285	$	86,377

Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statement of cash flows.

(in thousands)	December 31, 2019		December 31, 2018
Cash and cash equivalents	$	112,279	$	141,714
Restricted cash		3,206		5,477
Total cash, cash equivalents and restricted cash	$	115,485	$	147,191

Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses	$ 181,300	$ 223,800
Research and development credits	71,900	62,200
Capitalized research and development	28,000	34,800
Share-based compensation expense	22,900	17,300
Operating lease assets	23,300	100
Intangible assets	49,300	9,400
Other	18,500	19,100
Total deferred tax assets	395,200	366,700
Deferred tax liabilities:
Convertible senior notes	(24,100)	(26,400)
Operating lease liabilities	(18,200)
Other	(6,900)	(5,100)
Total deferred tax liabilities	(49,200)	(31,500)
Net of deferred tax assets and liabilities	346,000	335,200
Valuation allowance	$ (346,000)	$ (335,200)

Summary of Quarterly Results of Operations (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Total revenues

$ 244,010

$ 222,094

$ 183,580

$ 138,403

$ 131,492

$ 151,757

$ 96,905

$ 71,086

$ 788,087

$ 451,240

$ 161,626

Total operating expenses

195,289

^[1]

131,996

^[1]

149,119

^[1]

239,400

^[1]

109,621

97,434

98,757

108,533

715,804

414,345

292,987

Net (loss) income

$ 34,000

^[1]

$ 53,789

^[1]

$ 51,338

^[1]

$ (102,115)

^[1]

$ 18,078

$ 50,764

$ (5,913)

$ (41,818)

$ 37,012

$ 21,111

$ (142,542)

Net (loss) income per share, basic

$ 0.37

^[1]

$ 0.59

^[1]

$ 0.56

^[1]

$ (1.12)

^[1]

$ 0.20

$ 0.56

$ (0.07)

$ (0.47)

$ 0.40

$ 0.23

$ (1.62)

Net (loss) income per share, diluted

$ 0.35

^[1]

$ 0.56

^[1]

$ 0.54

^[1]

$ (1.12)

^[1]

$ 0.19

$ 0.52

$ (0.07)

$ (0.47)

$ 0.39

$ 0.22

$ (1.62)

Weighted average common shares outstanding, basic

92,182,000

91,859,000

91,389,000

91,056,000

90,742,000

90,555,000

90,100,000

89,526,000

91,627,000

90,235,000

88,089,000

Weighted average common shares outstanding, diluted

97,229,000

96,074,000

94,779,000

91,056,000

95,724,000

96,798,000

90,100,000

89,526,000

95,732,000

95,386,000

88,089,000

[1]

In connection with the payment of the upfront fee pursuant to our collaboration and license agreement with Voyager, we recorded a charge of $113.1 million, accounted for as IPR&D, in the first quarter of 2019. In the second quarter of 2019, we entered into an amendment to the collaboration and license agreement with Voyager, pursuant to which we paid Voyager $5.0 million upfront, accounted for as IPR&D, to obtain outside the U.S. rights to the Friedreich’s ataxia program. In connection with the payment of the upfront fee pursuant to our collaboration with Xenon, we recorded a charge of $36.2 million, accounted for as IPR&D, in the fourth quarter of 2019.

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

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

+ References + Details

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2019

Investments Debt And Equity Securities [Abstract]

Available-For-Sale Debt Securities

Available-for-sale debt securities consisted of the following:

	December 31,
(in thousands)	2019		2018
Commercial paper	$	144,472	$	94,572
Corporate debt securities		521,946		544,978
Securities of government-sponsored entities		191,481		85,677
Total marketable securities	$	857,899	$	725,227

Amortized Cost, Gross Unrealized Gain (Loss) Positions and Estimated Fair Value for Available-For-Sale Debt Securities

The following table presents the amortized cost, gross unrealized gain (loss) positions and estimated fair value for available-for-sale debt securities, aggregated by investment category.

(in thousands)	Contractual Maturity (in years)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Estimated Fair Value
December 31, 2019:
Classified as current assets:
Commercial paper	Less than 1	$	144,460	$	27	$	(15	)	$	144,472
Corporate debt securities	Less than 1		270,485		557		(42	)		271,000
Securities of government-sponsored entities	Less than 1		142,351		422		—			142,773
blank		$	557,296	$	1,006	$	(57	)	$	558,245
Classified as non-current assets:
Corporate debt securities	1 to 2	$	250,499	$	515	$	(68	)	$	250,946
Securities of government-sponsored entities	1 to 2		48,691		19		(2	)		48,708
blank		$	299,190	$	534	$	(70	)	$	299,654
blank
December 31, 2018:
Classified as current assets:
Commercial paper	Less than 1	$	94,617	$	—	$	(45	)	$	94,572
Corporate debt securities	Less than 1		395,385		—		(1,598	)		393,787
Securities of government-sponsored entities	Less than 1		20,887		8		(55	)		20,840
blank		$	510,889	$	8	$	(1,698	)	$	509,199
Classified as non-current assets:
Corporate debt securities	1 to 2	$	151,594	$	66	$	(469	)	$	151,191
Securities of government-sponsored entities	1 to 2		64,676		162		(1	)		64,837
blank		$	216,270	$	228	$	(470	)	$	216,028

Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position

The following table presents the estimated fair value and gross unrealized loss position for available-for-sale debt securities, aggregated by investment category and length of time that such securities have been in a continuous loss position.

	Less Than 12 Months					12 Months or Greater					Total
(in thousands)	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
December 31, 2019:
Commercial paper	$	33,070	$	(15	)	$	—	$	—		$	33,070	$	(15	)
Corporate debt securities		186,052		(110	)		—		—			186,052		(110	)
Securities of government-sponsored entities		15,002		(2	)		—		—			15,002		(2	)
blank	$	234,124	$	(127	)	$	—	$	—		$	234,124	$	(127	)
blank
December 31, 2018:
Commercial paper	$	51,927	$	(45	)	$	—	$	—		$	51,927	$	(45	)
Corporate debt securities		274,696		(746	)		234,798		(1,321	)		509,494		(2,067	)
Securities of government-sponsored entities		4,999		(1	)		10,947		(55	)		15,946		(56	)
blank	$	331,622	$	(792	)	$	245,745	$	(1,376	)	$	577,367	$	(2,168	)

Share-Based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation

Note 8. Share-Based Compensation

Share-Based Compensation Plans. In May 2011, we adopted the Neurocrine Biosciences, Inc. 2011 Equity Incentive Plan, as amended, or the 2011 Plan, pursuant to which 21 million shares of our common stock are authorized for issuance. The 2011 Plan provides for the grant of stock options that qualify as incentive stock options under Section 422 of the Internal Revenue Code of 1986, as amended, non-statutory stock options, restricted stock awards, restricted stock unit awards, or RSUs, stock appreciation rights, performance stock awards, performance-based restricted stock units, or PRSUs, and other forms of equity compensation. In May 2018, we adopted the Neurocrine Biosciences, Inc. ESPP pursuant to which 300,000 shares of our common stock are authorized for issuance. During 2019, we issued 78,000 shares of our common stock under the ESPP. No purchases occurred under the ESPP during 2018.

We previously issued stock options and RSUs under the Neurocrine Biosciences, Inc. Inducement Plan, or the Inducement Plan, to certain employees. Pursuant to the Inducement Plan, we granted 70,000 stock options and 20,000 RSUs in 2018 and 410,000 stock options and 12,500 RSUs in 2017. We did not grant any stock options or RSUs pursuant to the Inducement Plan during 2019. These stock option grants have a four-year vesting period and the RSUs generally have vesting periods of three to four years. We currently have a total of 211,000 stock options and RSUs outstanding under this Inducement Plan.

At December 31, 2019, 6.8 million shares of common stock remained available for the future grant of awards under the 2011 Plan. Only share awards made under the 2011 Plan that are subsequently cancelled due to forfeiture or expiration are returned to the share pool available for future grants.

We issue new shares upon the exercise of stock options, the issuance of stock bonus awards, and the vesting of RSUs and PRSUs. At December 31, 2019, 7.8 million shares of common stock were reserved for such issuances.

Vesting Provisions of Share-Based Compensation. Stock options generally have terms of ten years from the date of grant, and generally vest over a three to four-year period. The maximum contractual term for all options granted from the 2011 Plan is ten years. RSUs granted under the 2011 Plan generally have vesting periods of four years. PRSUs granted under the 2011 Plan vest based on the achievement of certain pre-defined Company-specific performance criteria and expire four to five years from the grant date.

Share-Based Compensation. The compensation cost that has been included in the statements of operations and comprehensive income (loss) for all share-based compensation arrangements is as follows:

	Year Ended December 31,
(in thousands)	2019		2018		2017
Sales, general and administrative expense	$	49,489	$	31,847	$	27,951
Research and development expense		25,773		26,221		14,571
Share-based compensation expense	$	75,262	$	58,068	$	42,522

Stock Options. The exercise price of our stock options granted is equal to the closing price of our common stock on the date of grant. The estimated fair value of each stock option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for option grants:

	Year Ended December 31,
(in thousands)	2019	2018	2017
Risk-free interest rate	2.4%	2.5%	2.0%
Expected volatility of common stock	54.8%	59.5%	58.0%
Dividend yield	0.0%	0.0%	0.0%
Expected option term	5.4 years	4.7 years	5.7 years

We estimate the fair value of stock options using a Black-Scholes option-pricing model on the date of grant. The fair values of equity instruments are recognized and amortized on a straight-line basis over the requisite service period. The Black-Scholes option-pricing model incorporates various and highly sensitive assumptions including expected volatility, term and interest rates. The expected volatility is based on the historical volatility of our common stock over the most recent period commensurate with the estimated expected term of our stock options. The expected option term is estimated based on historical experience as well as the status of the employee. For example, directors and officers have a longer expected option term than all other employees. The risk-free rate for periods within the contractual life of the option is based upon observed interest rates appropriate for the expected term of our employee stock options. We have never declared or paid dividends and has no plans to do so in the foreseeable future.

Our determination of fair value is affected by our stock price as well as a number of assumptions that require judgment. The weighted-average fair values of stock options granted during 2019, 2018 and 2017 estimated as of the grant date using the Black-Scholes option-pricing model, were $41.74, $43.42 and $25.11, respectively.

A summary of activity related to stock options follows:

	Year Ended December 31,
	2019					2018					2017
(in thousands, except weighted average data)	Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price
Outstanding at January 1		5,746		$	41.38		6,356		$	28.83		6,112		$	20.01
Granted		1,416			82.27		1,040			84.97		1,807			46.55
Exercised		(983	)		27.95		(1,592	)		18.95		(1,353	)		10.41
Canceled		(72	)		75.09		(58	)		64.67		(210	)		43.05
Outstanding at December 31		6,107		$	52.62		5,746		$	41.38		6,356		$	28.83

Stock options outstanding at December 31, 2019 had a weighted average remaining contractual term of 6.7 years.

For 2019, 2018 and 2017 share-based compensation expense related to stock options was $36.5 million, $35.4 million and $28.2 million, respectively. At December 31, 2019, there was approximately $75.0 million of unamortized compensation cost related to stock options, which we expect to recognize over a weighted average remaining vesting period of approximately 2.4 years. At

December 31, 2019, there were approximately 4.0 million stock options exercisable with a weighted average exercise price of $41.01 and a weighted-average remaining contractual term of 5.8 years. The total intrinsic value, which is the amount by which the exercise price was exceeded by the sale price of our common stock on the date of sale, of stock option exercises during 2019, 2018, and 2017 was $64.3 million, $117.0 million and $61.4 million, respectively. At December 31, 2019, the total intrinsic value of stock options outstanding and exercisable was $335.7 million and $268.2 million, respectively. Cash received from stock option exercises for 2019, 2018 and 2017 was $27.3 million, $29.5 million, and $13.9 million, respectively.

Restricted Stock Units. The fair value of RSUs is based on the closing sale price of our common stock on the date of issuance. For 2019, 2018, and 2017 share-based compensation expense related to RSUs was $30.4 million, $21.9 million, and $13.9 million, respectively. As of December 31, 2019, there was approximately $75.5 million of unamortized compensation cost related to RSUs, which is expected to be recognized over a weighted average remaining vesting period of approximately 2.4 years.

The total intrinsic value of RSUs converted into common shares for 2019, 2018 and 2017 was $36.1 million, $35.5 million, and $14.9 million, respectively. The RSUs, at the election of eligible employees, may be subject to deferred delivery arrangement. The total intrinsic value of RSUs outstanding at December 31, 2019 was $147.2 million based on our closing stock price on that date.

A summary of activity related to RSUs follows:

	Year Ended December 31,
	2019					2018					2017
(in thousands, except weighted average data)	Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit
Outstanding at January 1		1,133		$	62.31		1,080		$	40.30		883		$	29.33
Granted		707			82.66		540			85.29		588			47.21
Cancelled		(56	)		74.49		(58	)		36.21		(41	)		40.62
Converted into common shares		(416	)		54.30		(429	)		59.23		(350	)		24.19
Outstanding at December 31		1,368		$	74.77		1,133		$	62.31		1,080		$	40.30

Performance-Based Restricted Stock Units. We had 0.3 million PRSUs outstanding at both December 31, 2019 and 2018. During 2018, we granted approximately 0.2 million PRSUs that vest based on the achievement of certain pre-defined Neurocrine-specific performance criteria and expire approximately four to five years from the grant date. No PRSUs were granted during 2019 or 2017. The fair value of PRSUs is estimated based on the closing sale price of our common stock on the date of grant. Expense recognition for PRSUs commences when attainment of the performance-based criteria is determined to be probable. We recognized expense of $5.6 million for 2019 and $0.4 million for 2017 related to PRSUs. We recognized no expense related to PRSUs for 2018. At December 31, 2019, total unrecognized estimated compensation expense related to PRSUs was $14.1 million and the total intrinsic value of PRSUs outstanding was $35.5 million based on our closing stock price on that date. The total intrinsic value of PRSUs converted into common shares was $8.8 million for 2017.

Employee Stock Purchase Plan. Under the ESPP, eligible employees may purchase shares of our common stock at a discount semi-annually based on a percentage of their annual compensation. The discounted purchase price is equal to the lower of 85% of (i) the market value per share of the common stock on the first day of the offering period or (ii) the market value per share of common stock on the purchase date. Share-based compensation expense recognized under the ESPP was $2.7 million for 2019 and $0.8 million for 2018.

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	NEUROCRINE BIOSCIENCES, INC.
Entity Central Index Key	0000914475
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		92,292,392
Entity Public Float			$ 5,752,910,928
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	NBIX
Entity File Number	0-22705
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0525145
Entity Address, Address Line One	12780 El Camino Real
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	858
Local Phone Number	617-7600
Document Transition Report	false
Document Annual Report	true
Documents Incorporated by Reference [Text Block]	Portions of the registrant’s definitive proxy statement relating to the registrant’s annual meeting of stockholders to be filed pursuant to Regulation 14A within 120 days following the end of the registrant’s fiscal year ended December 31, 2019 are incorporated by reference into Part III of this Form 10-K

License and Collaboration Agreements - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended				3 Months Ended								12 Months Ended			60 Months Ended	114 Months Ended
	Jan. 31, 2019	Feb. 28, 2017	Mar. 31, 2015	Jun. 30, 2010	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues					$ 244,010,000	$ 222,094,000	$ 183,580,000	$ 138,403,000	$ 131,492,000	$ 151,757,000	$ 96,905,000	$ 71,086,000	$ 788,087,000	$ 451,240,000	$ 161,626,000
Acquired in-process research and development													154,272,000	4,750,000	30,000,000
Restricted investment in equity securities fair value amount					55,868,000								55,868,000			$ 55,868,000	$ 55,868,000
Development and Regulatory Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments					4,900,000,000								4,900,000,000			4,900,000,000	4,900,000,000
AbbVie
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments received				$ 75,000,000.0
Revenues														40,000,000.0	30,000,000.0
Patent rights period				ten years or the life of the related patent rights.
Collaborative arrangement right description				We will be entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights.
Collaboration termination notice period				180 days
AbbVie \| Royalty
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues													14,300,000	1,600,000
AbbVie \| Regulatory and Clinical Results and FDA Acceptance Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues													20,000,000.0
AbbVie \| Topic 606
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments received				$ 75,000,000.0
AbbVie \| Development and Regulatory Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential development and regulatory milestone payment receipts				480,000,000.0
Revenues																	135,000,000.0
AbbVie \| Commercial Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential commercial milestone payment receipts				$ 50,000,000.0
B I A L
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Acquired in-process research and development		$ 30,000,000.0
B I A L \| Parkinson's Disease
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential payments for regulatory milestones					20,000,000.0								20,000,000.0			20,000,000.0	20,000,000.0
B I A L \| Event Based Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments made for regulatory milestones					10,000,000.0								10,000,000.0			10,000,000.0	10,000,000.0
B I A L \| R&D Expense and FDA Acceptance Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments made for regulatory milestones							10,000,000.0
B I A L \| Regulatory Approval and Net Sales Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 95,000,000.0
Voyager Therapeutics \| Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration termination notice period	180 days
Upfront payments made	$ 115,000,000.0
Restricted investment in equity securities cost	$ 50,000,000.0
Share price	$ 11.9625
Restricted investment in equity securities fair value amount	$ 54,700,000
Voyager Therapeutics \| Collaboration and License Agreement \| IPR&D
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Acquired in-process research and development							$ 5,000,000.0	$ 113,100,000
Voyager Therapeutics \| Collaboration and License Agreement \| Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restricted investment in equity securities number of shares	4.2
Voyager Therapeutics \| Collaboration and License Agreement \| Development, Regulatory and Commercial Milestone Payment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 1,700,000,000
Xenon \| Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments made					30,000,000.0								30,000,000.0			30,000,000.0	30,000,000.0
Restricted investment in equity securities cost					$ 20,000,000.0								$ 20,000,000.0			$ 20,000,000.0	$ 20,000,000.0
Share price					$ 14.196								$ 14.196			$ 14.196	$ 14.196
Restricted investment in equity securities fair value amount					$ 14,100,000								$ 14,100,000			$ 14,100,000	$ 14,100,000
Xenon \| Collaboration and License Agreement \| IPR&D
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Acquired in-process research and development					$ 36,200,000
Xenon \| Collaboration and License Agreement \| Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Restricted investment in equity securities number of shares					1.4								1.4			1.4	1.4
Xenon \| Collaboration and License Agreement \| Development, Regulatory and Commercial Milestone Payment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments					$ 1,700,000,000								$ 1,700,000,000			$ 1,700,000,000	$ 1,700,000,000
Mitsubishi Tanabe
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments received			$ 30,000,000.0
Revenues															$ 15,000,000.0
Patent rights period			the longer of ten years or the life of the related patent rights.
Collaborative arrangement right description			Under the terms of the agreement, MTPC is responsible for all third-party development, marketing and commercialization costs in Japan and other select Asian markets and we would be entitled to a percentage of sales of INGREZZA in Japan and other select Asian markets for the longer of ten years or the life of the related patent rights. Further, the collaboration effort between the parties to advance INGREZZA towards commercialization in Japan and other select Asian markets is governed by joint steering and development committees with representatives from both parties. There are no performance, cancellation, termination or refund provisions in the agreement that would have a material financial consequence to us. We do not directly control when event-based payments will be achieved or when royalty payments will begin. MTPC may terminate the agreement at its discretion upon 180 days’ written notice to us. In such event, all INGREZZA product rights for Japan and other select Asian markets would revert to us.
Collaboration termination notice period			180 days
Potential milestone payment receipts			$ 85,000,000.0
Revenues recognized under collaboration agreement														$ 0		20,600,000
Deferred revenue recognized													900,000
Up-front license fees			$ 30,000,000.0
Deferred revenues					$ 9,400,000								$ 9,400,000			$ 9,400,000	$ 9,400,000

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Business Activities	Business Activities. Neurocrine Biosciences, Inc., or Neurocrine, the Company, we, our or us, was incorporated in California in 1992 and reincorporated in Delaware in 1996. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of Neurocrine. We also have two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. both of which were formed in December 2014 and are inactive. We are a commercial-stage biopharmaceutical company focused on discovering and developing innovative and life-changing treatments for patients with serious, challenging and under-addressed neurological, endocrine and psychiatric disorders. We specialize in targeting and interrupting disease-causing mechanisms involving the interconnected pathways of the nervous and endocrine systems. Currently, we are primarily focused on the commercialization of INGREZZA^® (valbenazine) in the United States, our first U.S. Food and Drug Administration, or FDA, approved product. In April 2017, we received FDA approval of our first product, INGREZZA, for the treatment of adults with tardive dyskinesia, or TD. Shortly after receiving FDA approval, we began commercializing INGREZZA in the U.S. using a specialty sales force primarily focused on educating physicians who treat patients with TD, including psychiatrists and neurologists. In addition to our first marketed product, our collaboration partner, AbbVie Inc., or AbbVie, received approval of ORILISSA^® (elagolix) for the management of moderate to severe endometriosis pain in women from the FDA in July 2018 and Health Canada in October 2018. We are eligible to receive royalties at tiered percentage rates on any net sales of ORILISSA. Our late-stage pipeline includes opicapone as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients, elagolix for the treatment of heavy menstrual bleeding, or HMB, associated with uterine fibroids in women, valbenazine for the treatment of chorea in adult patients with Huntington’s disease, or HD, and NBIB-1817 (VY-AADC) for the treatment of advanced Parkinson’s disease patients with motor fluctuations that are refractory to medical management. Our product candidates for uterine fibroids and advanced Parkinson’s disease are partnered with AbbVie and Voyager Therapeutics, Inc., or Voyager, respectively. In December 2019, we entered into a license and collaboration agreement with Xenon Pharmaceuticals Inc, or Xenon, a clinical-stage biopharmaceutical company. Pursuant to the terms of the agreement, we acquired an exclusive license to NBI-921352 (XEN901), a clinical-stage candidate with potential in epilepsy. In January 2020, we announced a collaboration and optional licensing agreement with Idorsia Pharmaceuticals Ltd, granting us an option to license ACT-709478, a potent, selective, orally active and brain penetrating T-type calcium channel blocker, in clinical development for the treatment of a rare pediatric epilepsy. The option also includes a research collaboration to discover, identify and develop additional novel T-type calcium channel blockers.
Principles of Consolidation	Principles of Consolidation. The consolidated financial statements include the accounts of Neurocrine as well as our wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Reclassifications. Certain amounts in the consolidated financial statements for 2018 and 2017 have been reclassified to conform with the presentation adopted in the current year period, including an increase of $4.8 million and $30.0 million to acquired in-process research and development for 2018 and 2017, respectively, and a corresponding decrease to research and development in the same periods. These reclassifications had no impact on operating income (loss), net income (loss) or net income (loss) per share.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates.
Industry Segment and Geographic Information	Industry Segment and Geographic Information. We operate in a single industry segment – the discovery, development and marketing of pharmaceuticals for the treatment of neurological and endocrine-based diseases and disorders. We had no foreign-based operations during any of the years presented.
Cash Equivalents	Cash Equivalents. We consider all highly liquid investments that are readily convertible into cash and have an original maturity of three months or less at the time of purchase to be cash equivalents.
Accounts Receivable	Accounts Receivable. Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks and any allowance for doubtful accounts. We estimate the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of our customers and individual customer circumstances. To date, an allowance for doubtful accounts has not been material.
Marketable Securities	Marketable Securities. Marketable securities consist of investments in certificates of deposit, corporate debt securities and securities of government-sponsored entities. We classify marketable securities as available-for-sale. Marketable securities are recorded at fair value, with unrealized gains and losses included in comprehensive income (loss), until realized. Realized gains and losses are included in investment income and other, net on a specific-identification basis. Marketable securities classified as current have maturities of less than one year. Marketable securities classified as non-current have maturities of one to two years. We review marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Factors considered in determining whether an impairment is other-than-temporary include the length of time and extent to which the marketable security has been less than the cost basis, the financial condition of the issuer and our intent and ability to hold such marketable security until recovery of the associated amortized cost basis. Based on our evaluation, no such other-than-temporary impairments were identified at December 31, 2019 and 2018. Further, we do not intend to sell our marketable security investments and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases, which may be maturity.
Restricted Equity Securities	Restricted Equity Securities. Investments in equity securities of certain companies that are subject to holding period restrictions longer than one year are carried at fair value using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of similar companies. Unrealized gains and losses on investments in restricted equity securities are included in other expense, net.
Fair Value of Financial Instruments	Fair Value of Financial Instruments. We record cash equivalents, marketable securities and restricted equity securities at fair value based on a fair value hierarchy that distinguishes between assumptions based on market data (observable inputs) and our own assumptions (unobservable inputs). The hierarchy consists of three levels: Level 1 – Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3 – Unobservable inputs that reflect our own assumptions about the assumptions that market participants would use in pricing the asset or liability when there is little, if any, market activity for the asset or liability at the measurement date. The fair value of marketable securities is determined using proprietary valuation models and analytical tools, which utilize market pricing or prices for similar instruments that are both objective and publicly available, such as matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities and bids and offers. The fair value of restricted equity securities is determined using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of similar companies. Significant changes in any of those inputs in isolation would result in a significantly higher or lower fair value measurement. The carrying amounts of accounts receivable and accounts payable and accrued liabilities approximate their fair values due to their short-term maturities. There were no transfers between levels in the fair value hierarchy during 2019 or 2018.
Inventory	Inventory. Inventory is valued at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on the first-in, first-out method. We assess the valuation of our inventory on a quarterly basis and adjust the value for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand. Inventory costs resulting from these adjustments are recognized as cost of sales in the period in which they are incurred. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, we capitalize pre-launch inventory costs prior to regulatory approval.
Property and Equipment	Property and Equipment. Property and equipment are stated at cost and depreciated over the estimated useful lives of the assets using the straight-line method. Equipment is depreciated over an average estimated useful life of three to seven years. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the remaining lease term. Depreciation expense was $7.5 million for 2019, $4.0 million for 2018 and $2.4 million for 2017.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If the carrying amount is not recoverable, we measure the amount of any impairment by comparing the carrying value of the asset to the present value of the expected future cash flows associated with the use of the asset.
Revenue Recognition	Revenue Recognition. We recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. Revenue is recognized using a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. Product Sales, Net Our product sales, net consist of sales of INGREZZA in the U.S. to a limited network of specialty pharmacy providers, which delivers INGREZZA to patients by mail, and a specialty distributor, which distributes INGREZZA primarily to closed-door pharmacies and government facilities. Product sales, net are recognized at the time the customer takes possession of the product. Revenues from product sales are recorded net of reserves established for applicable discounts and allowances that are offered within contracts with our customers, payors and other third parties. Our process for estimating reserves established for these variable consideration components does not differ materially from historical practices. The transaction price, which includes variable consideration reflecting the impact of discounts and allowances, may be subject to constraint and is included in the net sales price only to the extent that it is probable that a significant reversal of the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment. Our significant categories of sales discounts and allowances are as follows: Product discounts – product discounts are based on payment terms extended to our customers, which include incentives offered for prompt payment. We maintain a reserve for product discounts based on our historical experience, including the timing of customer payments. To date, actual product discounts have not differed materially from our estimates. Product returns – our contracts with customers provide for product returns only if the product is damaged or there has been an error in shipment. Returns based on product expiry are not permitted. To date, product returns have not been significant, and a reserve has not been established. Government rebates – we are obligated to pay rebates for mandated discounts under the Medicaid Drug Rebate Program. The liability for such rebates consist of invoices received for claims from prior quarters that remain unpaid or for which an invoice has not been received and estimated rebates for the current applicable reporting period. Such rebates are primarily estimated based upon, actual historical rebates, estimated payor mix, state and federal regulations and related contractual terms and are recorded as a reduction of product sales in the same period the related revenue is recognized. To date, actual government rebates have not differed materially from our estimates. Chargebacks – the difference between the list price, or the price at which we sell INGREZZA product to our customers, and the contracted price, or the price at which our customers sell INGREZZA product to qualified healthcare professionals, is charged back to us by our customers. In addition to actual chargebacks received, we maintain a reserve for chargebacks based on estimated contractual discounts on INGREZZA product inventory levels on hand in our distribution channel. To date, actual chargebacks have not differed materially from our estimates. Payor and pharmacy rebates – we are obligated to pay rebates as a percentage of sales under payor and pharmacy contracts. We estimate these rebates based on actual historical rebates, contractual rebate percentages, sales made through the payor channel and purchases made by pharmacies. To date, actual payor and pharmacy rebates have not differed materially from our estimates. Copay assistance – we offer qualified patients financial assistance with prescription drug co-payments required by insurance. We accrue for copay assistance based on estimated claims and the cost per claim we expect to receive associated with inventory that remains in the distribution channel at period end. To date, actual copay assistance has not differed materially from our estimates. Collaboration Revenue We have entered into collaboration and licensing agreements under which we license certain rights to our product candidates to third parties. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; development, regulatory, and/or commercial milestone payments; and royalties on net sales of licensed products. Licenses of intellectual property – if the license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we use judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone payments – at the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, we evaluate whether achieving the milestones is considered probable and estimate the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone is included in the transaction price. Milestone payments that are not within our control, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer. Royalty revenue – for arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Each quarterly period, sales-based royalties are recorded based on estimated quarterly net sales of ORILISSA. Differences between actual results and estimated amounts are adjusted for in the period in which they become known, which typically follows the quarterly period in which the estimate was made. To date, actual royalties received have not differed materially from our estimates.
Concentration of Credit Risk	Concentration of Credit Risk. We do not currently have any of our own manufacturing facilities and therefore we depend on an outsourced manufacturing strategy for the production of INGREZZA for commercial use and for the production of our product candidates in clinical trials. We have contracts with one third-party manufacturer approved for the commercial production of INGREZZA’s capsules at two separate sites and two third-party manufacturers approved for the production of INGREZZA’s API. Although there are potential sources of supply other than our existing suppliers, any new supplier would be required to qualify under applicable regulatory requirements. We have entered into distribution agreements with a limited number of specialty pharmacy providers and a specialty distributor, and all of our product sales are to these customers. Our two largest customers represented approximately 86% of our product revenue for 2019 and a significant majority of our accounts receivable balance at December 31, 2019. For 2018 and 2017, our three largest customers represented approximately 93% of our product revenue and substantially all of our accounts receivable balance at December 31, 2018 and 2017. Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, investments and accounts receivables. We established guidelines to limit our exposure to credit risk by placing investments with high credit quality financial institutions, diversifying our investment portfolio and placing investments with maturities that maintain safety and liquidity.
Cost of Sales	Cost of Sales. Cost of sales includes third-party manufacturing, transportation, freight and indirect overhead costs associated with the manufacture and distribution of INGREZZA, royalty fees on net sales of ORILISSA and adjustments for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand.
Research and Development Expenses	Research and Development Expenses. R&D expenses consist primarily of salaries, payroll taxes, employee benefits and share-based compensation charges for those individuals involved in ongoing R&D efforts; as well as scientific consulting fees, preclinical and clinical trial costs, R&D facilities costs, laboratory supply costs and depreciation of scientific equipment. All such costs are charged to R&D expense as incurred. These expenses result from our independent R&D efforts, as well as efforts associated with collaborations, in-licenses and third-party funded research arrangements.
Asset Acquisitions	Asset Acquisitions. We account for acquisitions of an asset or group of assets that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the assets acquired on the basis of their relative fair values. No goodwill is recognized in an asset acquisition. Intangible assets that are acquired in an asset acquisition for use in R&D activities which have no alternative future use are expensed as in-process research and development, or IPR&D, on the acquisition date. Future costs to develop these assets are recorded to R&D expense as they are incurred.
Advertising Expense	Advertising Expense. In connection with the FDA approval and commercial launch of INGREZZA in April 2017, we began to incur advertising costs, which are expensed when services are performed, or goods are delivered. We incurred advertising costs related to our marketed product, INGREZZA, of $40.6 million in 2019, $20.5 million in 2018 and $10.1 million in 2017.
Share-Based Compensation	Share-Based Compensation. We grant stock options to purchase our common stock to eligible employees and directors and also grant certain employees restricted stock units, or RSUs, and performance-based restricted stock units, or PRSUs. Additionally, we allow employees to participate in an employee stock purchase plan, or ESPP. We estimate the fair value of stock options and shares to be issued under the ESPP using the Black-Scholes option-pricing model on the date of grant. Restricted stock units are valued based on the closing price of our common stock on the date of grant. The fair value of equity instruments expected to vest are recognized and amortized on a straight-line basis over the requisite service period of the award, which is generally three to four years; however, certain provisions in our equity compensation plans provide for shorter vesting periods under certain circumstances. The fair value of shares to be issued under the ESPP are recognized and amortized on a straight-line basis over the purchase period, which is generally six months. Additionally, we granted certain PRSUs that vest upon the achievement of certain pre-defined company-specific performance-based criteria. Expense related to these PRSUs is generally recognized ratably over the expected performance period once the pre-defined performance-based criteria for vesting becomes probable.
Net Income (Loss) Per Share	Net Income (Loss) Per Share. Basic net income (loss) per share is computed using the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share is computed using the weighted average number of common and potentially dilutive shares outstanding during the period, including the potentially dilutive shares resulting from the conversion of the 2024 Notes and excluding the effect of stock options and restricted stock outstanding for periods when their effect is anti-dilutive, using the treasury stock method. Convertible debt instruments that may be settled entirely or partly in cash (such as the 2024 Notes) may, in certain circumstances where the borrower has the ability and intent to settle in cash, be accounted for under the treasury stock method. We issued the 2024 Notes with a combination settlement feature, which we have the ability and intent to use upon conversion of the 2024 Notes, to settle the principal amount of debt for cash and the excess of the principal portion in shares of our common stock. As a result, of the approximately 6.8 million shares underlying the 2024 Notes, only the shares required to settle the excess of the principal portion would be considered dilutive under the treasury stock method. Further, approximately 0.3 million PRSUs were excluded from the calculation of diluted net income per share as the performance condition has not been achieved. In loss periods, basic net loss per share and diluted net loss per share are identical because the otherwise dilutive potential common shares become anti-dilutive and are therefore excluded.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements. ASU 2016-02. In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-02, “Leases (Topic 842)”, which requires lessees to recognize leases on the balance sheet and disclose key information about leasing arrangements. ASU 2016-02 establishes a right-of-use, or ROU, model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than twelve months. ASU 2016-02 also requires disclosures to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. On January 1, 2019, we adopted ASU 2016-02 using the modified retrospective transition method. Under this transition method, we recognized and measured leases that existed at the application date in our consolidated balance sheet as of January 1, 2019. Arrangements that are determined to be operating leases at inception are included in operating lease assets, noncurrent operating lease liabilities and other current liabilities in our consolidated balance sheets. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and operating lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As none of our operating leases provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset is adjusted for any prepaid or accrued lease payments and any lease incentives received. Operating lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, which we have elected to account for as a single lease component. Further, we have elected to recognize our short-term lease payments in profit or loss on a straight-line basis over the associated lease term and variable lease payments in the period in which the obligation for those payments is incurred. Short-term and variable lease payments were not material for 2019. In connection with the adoption of ASU 2016-02, we elected the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or initial direct costs for any existing leases. We also made accounting policy elections not to apply the recognition requirements under ASU 2016-02 to any of our short-term leases and to account for each separate lease and associated nonlease components as a single lease component for all of our leases. In preparation for implementation of ASU 2016-02, we finalized key accounting assessments and updated processes to appropriately recognize and present the associated financial information. Based on these efforts, the adoption of ASU 2016-02 resulted in the recognition of (1) ROU assets of $50.0 million and operating lease liabilities of $70.9 million, resulting from leases of office and laboratory space; (2) the derecognition of deferred rent of $20.9 million for certain lease incentives received; and (3) a cumulative-effect adjustment of $8.0 million to the opening balance of the accumulated deficit as of January 1, 2019, resulting from the recognition of an existing deferred gain on sale of real estate. The comparative prior period information continues to be reported under the accounting standards in effect during those periods. Further, we expect the adoption of ASU 2016-02 to be immaterial to our results of operations and cash flows on an ongoing basis. ASU 2018-07. In June 2018, the FASB issued ASU 2018-07, “Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting”, which expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees and applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. On January 1, 2019, we adopted ASU 2018-07 using the modified retrospective transition method with no impact on our consolidated financial statements. Further, we expect the adoption of ASU 2018-07 to be immaterial to our financial position, results of operations and cash flows on an ongoing basis.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements. ASU 2016-13. In June 2016, the FASB issued ASU 2016-13, "Measurement of Credit Losses on Financial Instruments". The standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, the standard requires allowances to be recorded instead of reducing the amortized cost of the investment. The standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. The standard is effective for interim and annual periods beginning after December 15, 2019. Based on the composition of our investment portfolio, current market conditions and historical credit loss activity, the adoption of ASU 2016-13 is not expected to have a material impact on our consolidated financial position, results of operations or the related disclosures.

Organization and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Organization and Summary of Significant Accounting Policies

Note 1. Organization and Summary of Significant Accounting Policies

Business Activities. Neurocrine Biosciences, Inc., or Neurocrine, the Company, we, our or us, was incorporated in California in 1992 and reincorporated in Delaware in 1996. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of Neurocrine. We also have two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. both of which were formed in December 2014 and are inactive.

We are a commercial-stage biopharmaceutical company focused on discovering and developing innovative and life-changing treatments for patients with serious, challenging and under-addressed neurological, endocrine and psychiatric disorders. We specialize in targeting and interrupting disease-causing mechanisms involving the interconnected pathways of the nervous and endocrine systems. Currently, we are primarily focused on the commercialization of INGREZZA^® (valbenazine) in the United States, our first U.S. Food and Drug Administration, or FDA, approved product.

In April 2017, we received FDA approval of our first product, INGREZZA, for the treatment of adults with tardive dyskinesia, or TD. Shortly after receiving FDA approval, we began commercializing INGREZZA in the U.S. using a specialty sales force primarily focused on educating physicians who treat patients with TD, including psychiatrists and neurologists.

In addition to our first marketed product, our collaboration partner, AbbVie Inc., or AbbVie, received approval of ORILISSA^® (elagolix) for the management of moderate to severe endometriosis pain in women from the FDA in July 2018 and Health Canada in October 2018. We are eligible to receive royalties at tiered percentage rates on any net sales of ORILISSA.

Our late-stage pipeline includes opicapone as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients, elagolix for the treatment of heavy menstrual bleeding, or HMB, associated with uterine fibroids in women, valbenazine for the treatment of chorea in adult patients with Huntington’s disease, or HD, and NBIB-1817 (VY-AADC) for the treatment of advanced Parkinson’s disease patients with motor fluctuations that are refractory to medical management. Our product candidates for uterine fibroids and advanced Parkinson’s disease are partnered with AbbVie and Voyager Therapeutics, Inc., or Voyager, respectively.

In December 2019, we entered into a license and collaboration agreement with Xenon Pharmaceuticals Inc, or Xenon, a clinical-stage biopharmaceutical company. Pursuant to the terms of the agreement, we acquired an exclusive license to NBI-921352 (XEN901), a clinical-stage candidate with potential in epilepsy.

In January 2020, we announced a collaboration and optional licensing agreement with Idorsia Pharmaceuticals Ltd, granting us an option to license ACT-709478, a potent, selective, orally active and brain penetrating T-type calcium channel blocker, in clinical development for the treatment of a rare pediatric epilepsy. The option also includes a research collaboration to discover, identify and develop additional novel T-type calcium channel blockers.

Principles of Consolidation. The consolidated financial statements include the accounts of Neurocrine as well as our wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Reclassifications. Certain amounts in the consolidated financial statements for 2018 and 2017 have been reclassified to conform with the presentation adopted in the current year period, including an increase of $4.8 million and $30.0 million to acquired in-process research and development for 2018 and 2017, respectively, and a corresponding decrease to research and development in the same periods. These reclassifications had no impact on operating income (loss), net income (loss) or net income (loss) per share.

Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates.

Industry Segment and Geographic Information. We operate in a single industry segment – the discovery, development and marketing of pharmaceuticals for the treatment of neurological and endocrine-based diseases and disorders. We had no foreign-based operations during any of the years presented.

Cash Equivalents. We consider all highly liquid investments that are readily convertible into cash and have an original maturity of three months or less at the time of purchase to be cash equivalents.

Accounts Receivable. Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks and any allowance for doubtful accounts. We estimate the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of our customers and individual customer circumstances. To date, an allowance for doubtful accounts has not been material.

Marketable Securities. Marketable securities consist of investments in certificates of deposit, corporate debt securities and securities of government-sponsored entities. We classify marketable securities as available-for-sale. Marketable securities are recorded at fair value, with unrealized gains and losses included in comprehensive income (loss), until realized. Realized gains and losses are included in investment income and other, net on a specific-identification basis. Marketable securities classified as current have maturities of less than one year. Marketable securities classified as non-current have maturities of one to two years.

We review marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Factors considered in determining whether an impairment is other-than-temporary include the length of time and extent to which the marketable security has been less than the cost basis, the financial condition of the issuer and our intent and ability to hold such marketable security until recovery of the associated amortized cost basis. Based on our evaluation, no such other-than-temporary impairments were identified at December 31, 2019 and 2018. Further, we do not intend to sell our marketable security investments and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases, which may be maturity.

Restricted Equity Securities. Investments in equity securities of certain companies that are subject to holding period restrictions longer than one year are carried at fair value using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of similar companies. Unrealized gains and losses on investments in restricted equity securities are included in other expense, net.

Fair Value of Financial Instruments. We record cash equivalents, marketable securities and restricted equity securities at fair value based on a fair value hierarchy that distinguishes between assumptions based on market data (observable inputs) and our own assumptions (unobservable inputs). The hierarchy consists of three levels:

Level 1 – Quoted prices (unadjusted) in active markets for identical assets or liabilities.

Level 2 – Quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability.

Level 3 – Unobservable inputs that reflect our own assumptions about the assumptions that market participants would use in pricing the asset or liability when there is little, if any, market activity for the asset or liability at the measurement date.

The fair value of marketable securities is determined using proprietary valuation models and analytical tools, which utilize market pricing or prices for similar instruments that are both objective and publicly available, such as matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities and bids and offers.

The fair value of restricted equity securities is determined using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of similar companies. Significant changes in any of those inputs in isolation would result in a significantly higher or lower fair value measurement.

The carrying amounts of accounts receivable and accounts payable and accrued liabilities approximate their fair values due to their short-term maturities.

There were no transfers between levels in the fair value hierarchy during 2019 or 2018.

Inventory. Inventory is valued at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on the first-in, first-out method. We assess the valuation of our inventory on a quarterly basis and adjust the value for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand. Inventory costs resulting from these adjustments are recognized as cost of sales in the period in which they are incurred. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, we capitalize pre-launch inventory costs prior to regulatory approval.

Property and Equipment. Property and equipment are stated at cost and depreciated over the estimated useful lives of the assets using the straight-line method. Equipment is depreciated over an average estimated useful life of three to seven years. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the remaining lease term. Depreciation expense was $7.5 million for 2019, $4.0 million for 2018 and $2.4 million for 2017.

Impairment of Long-Lived Assets. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If the carrying amount is not recoverable, we measure the amount of any impairment by comparing the carrying value of the asset to the present value of the expected future cash flows associated with the use of the asset.

Revenue Recognition. We recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. Revenue is recognized using a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation.

Product Sales, Net

Our product sales, net consist of sales of INGREZZA in the U.S. to a limited network of specialty pharmacy providers, which delivers INGREZZA to patients by mail, and a specialty distributor, which distributes INGREZZA primarily to closed-door pharmacies and government facilities. Product sales, net are recognized at the time the customer takes possession of the product.

Revenues from product sales are recorded net of reserves established for applicable discounts and allowances that are offered within contracts with our customers, payors and other third parties. Our process for estimating reserves established for these variable consideration components does not differ materially from historical practices. The transaction price, which includes variable consideration reflecting the impact of discounts and allowances, may be subject to constraint and is included in the net sales price only to the extent that it is probable that a significant reversal of the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment.

Our significant categories of sales discounts and allowances are as follows:

Product discounts – product discounts are based on payment terms extended to our customers, which include incentives offered for prompt payment. We maintain a reserve for product discounts based on our historical experience, including the timing of customer payments. To date, actual product discounts have not differed materially from our estimates.

Product returns – our contracts with customers provide for product returns only if the product is damaged or there has been an error in shipment. Returns based on product expiry are not permitted. To date, product returns have not been significant, and a reserve has not been established.

Government rebates – we are obligated to pay rebates for mandated discounts under the Medicaid Drug Rebate Program. The liability for such rebates consist of invoices received for claims from prior quarters that remain unpaid or for which an invoice has not been received and estimated rebates for the current applicable reporting period. Such rebates are primarily estimated based upon, actual historical rebates, estimated payor mix, state and federal regulations and related contractual terms and are recorded as a reduction of product sales in the same period the related revenue is recognized. To date, actual government rebates have not differed materially from our estimates.

Chargebacks – the difference between the list price, or the price at which we sell INGREZZA product to our customers, and the contracted price, or the price at which our customers sell INGREZZA product to qualified healthcare professionals, is charged back to us by our customers. In addition to actual chargebacks received, we maintain a reserve for chargebacks based on estimated contractual discounts on INGREZZA product inventory levels on hand in our distribution channel. To date, actual chargebacks have not differed materially from our estimates.

Payor and pharmacy rebates – we are obligated to pay rebates as a percentage of sales under payor and pharmacy contracts. We estimate these rebates based on actual historical rebates, contractual rebate percentages, sales made through the payor channel and purchases made by pharmacies. To date, actual payor and pharmacy rebates have not differed materially from our estimates.

Copay assistance – we offer qualified patients financial assistance with prescription drug co-payments required by insurance. We accrue for copay assistance based on estimated claims and the cost per claim we expect to receive associated with inventory that remains in the distribution channel at period end. To date, actual copay assistance has not differed materially from our estimates.

Collaboration Revenue

We have entered into collaboration and licensing agreements under which we license certain rights to our product candidates to third parties. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; development, regulatory, and/or commercial milestone payments; and royalties on net sales of licensed products.

Licenses of intellectual property – if the license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we use judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone payments – at the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, we evaluate whether achieving the milestones is considered probable and estimate the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone is included in the transaction price. Milestone payments that are not within our control, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer.

Royalty revenue – for arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Each quarterly period, sales-based royalties are recorded based on estimated quarterly net sales of ORILISSA. Differences between actual results and estimated amounts are adjusted for in the period in which they become known, which typically follows the quarterly period in which the estimate was made. To date, actual royalties received have not differed materially from our estimates.

Concentration of Credit Risk. We do not currently have any of our own manufacturing facilities and therefore we depend on an outsourced manufacturing strategy for the production of INGREZZA for commercial use and for the production of our product candidates in clinical trials. We have contracts with one third-party manufacturer approved for the commercial production of

INGREZZA’s capsules at two separate sites and two third-party manufacturers approved for the production of INGREZZA’s API. Although there are potential sources of supply other than our existing suppliers, any new supplier would be required to qualify under applicable regulatory requirements.

We have entered into distribution agreements with a limited number of specialty pharmacy providers and a specialty distributor, and all of our product sales are to these customers. Our two largest customers represented approximately 86% of our product revenue for 2019 and a significant majority of our accounts receivable balance at December 31, 2019. For 2018 and 2017, our three largest customers represented approximately 93% of our product revenue and substantially all of our accounts receivable balance at December 31, 2018 and 2017.

Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, investments and accounts receivables. We established guidelines to limit our exposure to credit risk by placing investments with high credit quality financial institutions, diversifying our investment portfolio and placing investments with maturities that maintain safety and liquidity.

Cost of Sales. Cost of sales includes third-party manufacturing, transportation, freight and indirect overhead costs associated with the manufacture and distribution of INGREZZA, royalty fees on net sales of ORILISSA and adjustments for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand.

Research and Development Expenses. R&D expenses consist primarily of salaries, payroll taxes, employee benefits and share-based compensation charges for those individuals involved in ongoing R&D efforts; as well as scientific consulting fees, preclinical and clinical trial costs, R&D facilities costs, laboratory supply costs and depreciation of scientific equipment. All such costs are charged to R&D expense as incurred. These expenses result from our independent R&D efforts, as well as efforts associated with collaborations, in-licenses and third-party funded research arrangements.

Asset Acquisitions. We account for acquisitions of an asset or group of assets that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the assets acquired on the basis of their relative fair values. No goodwill is recognized in an asset acquisition. Intangible assets that are acquired in an asset acquisition for use in R&D activities which have no alternative future use are expensed as in-process research and development, or IPR&D, on the acquisition date. Future costs to develop these assets are recorded to R&D expense as they are incurred.

Advertising Expense. In connection with the FDA approval and commercial launch of INGREZZA in April 2017, we began to incur advertising costs, which are expensed when services are performed, or goods are delivered. We incurred advertising costs related to our marketed product, INGREZZA, of $40.6 million in 2019, $20.5 million in 2018 and $10.1 million in 2017.

Share-Based Compensation. We grant stock options to purchase our common stock to eligible employees and directors and also grant certain employees restricted stock units, or RSUs, and performance-based restricted stock units, or PRSUs. Additionally, we allow employees to participate in an employee stock purchase plan, or ESPP.

We estimate the fair value of stock options and shares to be issued under the ESPP using the Black-Scholes option-pricing model on the date of grant. Restricted stock units are valued based on the closing price of our common stock on the date of grant. The fair value of equity instruments expected to vest are recognized and amortized on a straight-line basis over the requisite service period of the award, which is generally three to four years; however, certain provisions in our equity compensation plans provide for shorter vesting periods under certain circumstances. The fair value of shares to be issued under the ESPP are recognized and amortized on a straight-line basis over the purchase period, which is generally six months. Additionally, we granted certain PRSUs that vest upon the achievement of certain pre-defined company-specific performance-based criteria. Expense related to these PRSUs is generally recognized ratably over the expected performance period once the pre-defined performance-based criteria for vesting becomes probable.

Net Income (Loss) Per Share. Basic net income (loss) per share is computed using the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share is computed using the weighted average number of common and potentially dilutive shares outstanding during the period, including the potentially dilutive shares resulting from the conversion of the 2024 Notes and excluding the effect of stock options and restricted stock outstanding for periods when their effect is anti-dilutive, using the treasury stock method.

Convertible debt instruments that may be settled entirely or partly in cash (such as the 2024 Notes) may, in certain circumstances where the borrower has the ability and intent to settle in cash, be accounted for under the treasury stock method. We issued the 2024 Notes with a combination settlement feature, which we have the ability and intent to use upon conversion of the 2024 Notes, to settle the principal amount of debt for cash and the excess of the principal portion in shares of our common stock. As a result, of the approximately 6.8 million shares underlying the 2024 Notes, only the shares required to settle the excess of the principal portion would be considered dilutive under the treasury stock method. Further, approximately 0.3 million PRSUs were excluded from the calculation of diluted net income per share as the performance condition has not been achieved. In loss periods, basic net loss per share and diluted net loss per share are identical because the otherwise dilutive potential common shares become anti-dilutive and are therefore excluded.

Recently Adopted Accounting Pronouncements.

ASU 2016-02. In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-02, “Leases (Topic 842)”, which requires lessees to recognize leases on the balance sheet and disclose key information about leasing arrangements. ASU 2016-02 establishes a right-of-use, or ROU, model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than twelve months. ASU 2016-02 also requires disclosures to

meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. On January 1, 2019, we adopted ASU 2016-02 using the modified retrospective transition method. Under this transition method, we recognized and measured leases that existed at the application date in our consolidated balance sheet as of January 1, 2019.

Arrangements that are determined to be operating leases at inception are included in operating lease assets, noncurrent operating lease liabilities and other current liabilities in our consolidated balance sheets.

ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and operating lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As none of our operating leases provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease ROU asset is adjusted for any prepaid or accrued lease payments and any lease incentives received. Operating lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, which we have elected to account for as a single lease component. Further, we have elected to recognize our short-term lease payments in profit or loss on a straight-line basis over the associated lease term and variable lease payments in the period in which the obligation for those payments is incurred. Short-term and variable lease payments were not material for 2019.

In connection with the adoption of ASU 2016-02, we elected the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or initial direct costs for any existing leases. We also made accounting policy elections not to apply the recognition requirements under ASU 2016-02 to any of our short-term leases and to account for each separate lease and associated nonlease components as a single lease component for all of our leases.

In preparation for implementation of ASU 2016-02, we finalized key accounting assessments and updated processes to appropriately recognize and present the associated financial information. Based on these efforts, the adoption of ASU 2016-02 resulted in the recognition of (1) ROU assets of $50.0 million and operating lease liabilities of $70.9 million, resulting from leases of office and laboratory space; (2) the derecognition of deferred rent of $20.9 million for certain lease incentives received; and (3) a cumulative-effect adjustment of $8.0 million to the opening balance of the accumulated deficit as of January 1, 2019, resulting from the recognition of an existing deferred gain on sale of real estate. The comparative prior period information continues to be reported under the accounting standards in effect during those periods. Further, we expect the adoption of ASU 2016-02 to be immaterial to our results of operations and cash flows on an ongoing basis.

ASU 2018-07. In June 2018, the FASB issued ASU 2018-07, “Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting”, which expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees and applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. On January 1, 2019, we adopted ASU 2018-07 using the modified retrospective transition method with no impact on our consolidated financial statements. Further, we expect the adoption of ASU 2018-07 to be immaterial to our financial position, results of operations and cash flows on an ongoing basis.

Recently Issued Accounting Pronouncements.

ASU 2016-13. In June 2016, the FASB issued ASU 2016-13, "Measurement of Credit Losses on Financial Instruments". The standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, the standard requires allowances to be recorded instead of reducing the amortized cost of the investment. The standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. The standard is effective for interim and annual periods beginning after December 15, 2019.

Based on the composition of our investment portfolio, current market conditions and historical credit loss activity, the adoption of ASU 2016-13 is not expected to have a material impact on our consolidated financial position, results of operations or the related disclosures.

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Compensation Cost Related to Share Based Compensation

Share-Based Compensation. The compensation cost that has been included in the statements of operations and comprehensive income (loss) for all share-based compensation arrangements is as follows:

	Year Ended December 31,
(in thousands)	2019		2018		2017
Sales, general and administrative expense	$	49,489	$	31,847	$	27,951
Research and development expense		25,773		26,221		14,571
Share-based compensation expense	$	75,262	$	58,068	$	42,522

Weighted-Average Assumptions for Stock Option Grants using Black-Scholes Option-Pricing Model

The estimated fair value of each stock option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for option grants:

	Year Ended December 31,
(in thousands)	2019	2018	2017
Risk-free interest rate	2.4%	2.5%	2.0%
Expected volatility of common stock	54.8%	59.5%	58.0%
Dividend yield	0.0%	0.0%	0.0%
Expected option term	5.4 years	4.7 years	5.7 years

Summary and Changes in Stock Options Outstanding

A summary of activity related to stock options follows:

	Year Ended December 31,
	2019					2018					2017
(in thousands, except weighted average data)	Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price
Outstanding at January 1		5,746		$	41.38		6,356		$	28.83		6,112		$	20.01
Granted		1,416			82.27		1,040			84.97		1,807			46.55
Exercised		(983	)		27.95		(1,592	)		18.95		(1,353	)		10.41
Canceled		(72	)		75.09		(58	)		64.67		(210	)		43.05
Outstanding at December 31		6,107		$	52.62		5,746		$	41.38		6,356		$	28.83

Summary and Changes in Restricted Stock Units Outstanding

A summary of activity related to RSUs follows:

	Year Ended December 31,
	2019					2018					2017
(in thousands, except weighted average data)	Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit
Outstanding at January 1		1,133		$	62.31		1,080		$	40.30		883		$	29.33
Granted		707			82.66		540			85.29		588			47.21
Cancelled		(56	)		74.49		(58	)		36.21		(41	)		40.62
Converted into common shares		(416	)		54.30		(429	)		59.23		(350	)		24.19
Outstanding at December 31		1,368		$	74.77		1,133		$	62.31		1,080		$	40.30

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Investments Measured at Fair Value on Recurring Basis

Investments measured at fair value on a recurring basis consisted of the following:

				Fair Value Measurements Using
(in thousands)	Carrying Value			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
December 31, 2019:
Classified as current assets:
Cash and money market funds	$	112,279		$	112,279		$	—	$	—
Commercial paper		144,472			—			144,472		—
Securities of government-sponsored entities		142,773			—			142,773		—
Corporate debt securities		271,000			—			271,000		—
blank		670,524			112,279			558,245		—
Classified as long-term assets:
Certificates of deposit		3,206			3,206			—		—
Securities of government-sponsored entities		48,708			—			48,708		—
Corporate debt securities		250,946			—			250,946		—
Restricted equity securities		55,868			—			—		55,868
blank		1,029,252			115,485			857,899		55,868
Less cash and cash equivalents and restricted cash		(115,485	)		(115,485	)		—		—
Total investments	$	913,767		$	—		$	857,899	$	55,868
blank
December 31, 2018:
Classified as current assets:
Cash and money market funds	$	141,714		$	141,714		$	—	$	—
Commercial paper		94,572			—			94,572		—
Securities of government-sponsored entities		20,840			—			20,840		—
Corporate debt securities		393,787			—			393,787		—
blank		650,913			141,714			509,199		—
Classified as long-term assets:
Cash and money market funds		1,500			1,500			—		—
Certificates of deposit		3,977			3,977			—		—
Securities of government-sponsored entities		64,837			—			64,837		—
Corporate debt securities		151,191			—			151,191		—
blank		872,418			147,191			725,227		—
Less cash and cash equivalents and restricted cash		(147,191	)		(147,191	)		—		—
Total investments	$	725,227		$	—		$	725,227	$	—

Reconciliation of Restricted Equity Securities Measured at Fair Value on Recurring Basis

A reconciliation of restricted equity securities measured at fair value on a recurring basis follows.

(in thousands)
Balance at December 31, 2018	$	—
Investments in restricted equity securities		68,855
Net unrealized loss recognized on restricted equity securities during the period		(12,987)
Balance at December 31, 2019	$	55,868

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Revenues	$ 788,087	$ 451,240	$ 161,626
Operating expenses:
Cost of sales	7,428	4,889	1,254
Research and development	200,042	155,774	91,827
Acquired in-process research and development	154,272	4,750	30,000
Sales, general and administrative	354,062	248,932	169,906
Total operating expenses	715,804	414,345	292,987
Operating income (loss)	72,283	36,895	(131,361)
Other (expense) income:
Interest expense	(31,963)	(30,530)	(19,523)
Unrealized loss on restricted equity securities	(12,987)	0	0
Investment income and other, net	19,209	15,476	8,342
Total other expense, net	(25,741)	(15,054)	(11,181)
Income (loss) before provision for income taxes	46,542	21,841	(142,542)
Provision for income taxes	9,530	730
Net income (loss)	37,012	21,111	(142,542)
Unrealized gain (loss) on marketable securities	3,345	(82)	(1,532)
Comprehensive income (loss)	$ 40,357	$ 21,029	$ (144,074)
Net income (loss) per share, basic	$ 0.40	$ 0.23	$ (1.62)
Net income (loss) per share, diluted	$ 0.39	$ 0.22	$ (1.62)
Weighted average common shares outstanding, basic	91,627,000	90,235,000	88,089,000
Weighted average common shares outstanding, diluted	95,732,000	95,386,000	88,089,000
Product sales, net
Revenues:
Revenues	$ 752,900	$ 409,608	$ 116,626
Collaboration revenue
Revenues:
Revenues	$ 35,187	$ 41,632	$ 45,000

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

Note 13. Selected Quarterly Financial Data (Unaudited)

A summary of our quarterly results follows:

(in thousands, except per share data)	First Quarter			Second Quarter			Third Quarter		Fourth Quarter
Year Ended December 31, 2019:
Total revenues	$	138,403		$	183,580		$	222,094	$	244,010
Total operating expenses ⁽¹⁾	$	239,400		$	149,119		$	131,996	$	195,289
Net (loss) income ⁽¹⁾	$	(102,115	)	$	51,338		$	53,789	$	34,000
Net (loss) income per share, basic ⁽¹⁾	$	(1.12	)	$	0.56		$	0.59	$	0.37
Net (loss) income per share, diluted ⁽¹⁾	$	(1.12	)	$	0.54		$	0.56	$	0.35
Weighted average common shares outstanding, basic		91,056			91,389			91,859		92,182
Weighted average common shares outstanding, diluted		91,056			94,779			96,074		97,229
blank
Year Ended December 31, 2018:
Total revenues	$	71,086		$	96,905		$	151,757	$	131,492
Total operating expenses	$	108,533		$	98,757		$	97,434	$	109,621
Net (loss) income	$	(41,818	)	$	(5,913	)	$	50,764	$	18,078
Net (loss) income per share, basic	$	(0.47	)	$	(0.07	)	$	0.56	$	0.20
Net (loss) income per share, diluted	$	(0.47	)	$	(0.07	)	$	0.52	$	0.19
Weighted average common shares outstanding, basic		89,526			90,100			90,555		90,742
Weighted average common shares outstanding, diluted		89,526			90,100			96,798		95,724

(1) In connection with the payment of the upfront fee pursuant to our collaboration and license agreement with Voyager, we recorded a charge of $113.1 million, accounted for as IPR&D, in the first quarter of 2019. In the second quarter of 2019, we entered into an amendment to the collaboration and license agreement with Voyager, pursuant to which we paid Voyager $5.0 million upfront, accounted for as IPR&D, to obtain outside the U.S. rights to the Friedreich’s ataxia program. In connection with the payment of the upfront fee pursuant to our collaboration with Xenon, we recorded a charge of $36.2 million, accounted for as IPR&D, in the fourth quarter of 2019.

Marketable Securities

12 Months Ended

Dec. 31, 2019

Investments Debt And Equity Securities [Abstract]

Marketable Securities

Note 3. Marketable Securities

Available-for-sale debt securities consisted of the following:

	December 31,
(in thousands)	2019		2018
Commercial paper	$	144,472	$	94,572
Corporate debt securities		521,946		544,978
Securities of government-sponsored entities		191,481		85,677
Total marketable securities	$	857,899	$	725,227

The following table presents the amortized cost, gross unrealized gain (loss) positions and estimated fair value for available-for-sale debt securities, aggregated by investment category.

(in thousands)	Contractual Maturity (in years)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Aggregate Estimated Fair Value
December 31, 2019:
Classified as current assets:
Commercial paper	Less than 1	$	144,460	$	27	$	(15	)	$	144,472
Corporate debt securities	Less than 1		270,485		557		(42	)		271,000
Securities of government-sponsored entities	Less than 1		142,351		422		—			142,773
blank		$	557,296	$	1,006	$	(57	)	$	558,245
Classified as non-current assets:
Corporate debt securities	1 to 2	$	250,499	$	515	$	(68	)	$	250,946
Securities of government-sponsored entities	1 to 2		48,691		19		(2	)		48,708
blank		$	299,190	$	534	$	(70	)	$	299,654
blank
December 31, 2018:
Classified as current assets:
Commercial paper	Less than 1	$	94,617	$	—	$	(45	)	$	94,572
Corporate debt securities	Less than 1		395,385		—		(1,598	)		393,787
Securities of government-sponsored entities	Less than 1		20,887		8		(55	)		20,840
blank		$	510,889	$	8	$	(1,698	)	$	509,199
Classified as non-current assets:
Corporate debt securities	1 to 2	$	151,594	$	66	$	(469	)	$	151,191
Securities of government-sponsored entities	1 to 2		64,676		162		(1	)		64,837
blank		$	216,270	$	228	$	(470	)	$	216,028

	Less Than 12 Months					12 Months or Greater					Total
(in thousands)	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
December 31, 2019:
Commercial paper	$	33,070	$	(15	)	$	—	$	—		$	33,070	$	(15	)
Corporate debt securities		186,052		(110	)		—		—			186,052		(110	)
Securities of government-sponsored entities		15,002		(2	)		—		—			15,002		(2	)
blank	$	234,124	$	(127	)	$	—	$	—		$	234,124	$	(127	)
blank
December 31, 2018:
Commercial paper	$	51,927	$	(45	)	$	—	$	—		$	51,927	$	(45	)
Corporate debt securities		274,696		(746	)		234,798		(1,321	)		509,494		(2,067	)
Securities of government-sponsored entities		4,999		(1	)		10,947		(55	)		15,946		(56	)
blank	$	331,622	$	(792	)	$	245,745	$	(1,376	)	$	577,367	$	(2,168	)

Convertible Senior Notes

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Convertible Senior Notes

Note 5. Convertible Senior Notes

On May 2, 2017, we completed a private placement of $517.5 million in aggregate principal amount of 2.25% convertible senior notes due 2024, or the 2024 Notes, and entered into an indenture agreement that sets forth the details of all the terms and conditions of the 2024 Notes, or the 2024 Indenture. The 2024 Notes accrue interest at a fixed rate of 2.25% per year, payable semiannually in arrears on May 15 and November 15 of each year, beginning on November 15, 2017. The 2024 Notes mature on May 15, 2024. The net proceeds from the issuance of the 2024 Notes were approximately $502.8 million, after deducting commissions and the offering expenses payable by us.

Holders of the 2024 Notes may convert the 2024 Notes at any time prior to the close of business on the business day immediately preceding May 15, 2024, only under the following circumstances:

(i)

during any calendar quarter commencing after the calendar quarter ending on September 30, 2017 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day;

(ii)

during the five business-day period immediately after any 5 consecutive trading-day period (the measurement period) in which the trading price (as defined in the 2024 Indenture) per $1,000 principal amount of the 2024 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such trading day;

(iii)

upon the occurrence of specified corporate events, including a merger or a sale of all or substantially all of our assets; or

(iv)

if we call the 2024 Notes for redemption, until the close of business on the business day immediately preceding the redemption date.

On or after January 15, 2024, until the close of business on the scheduled trading day immediately preceding May 15, 2024, holders may convert their 2024 Notes at any time.

As the conditional conversion feature described under (i) above had been triggered as of December 31, 2019, holders of the 2024 Notes may convert the 2024 Notes at any time during the period beginning on January 2, 2020 and ending at the close of business on March 31, 2020. Accordingly, the 2024 Notes have been classified as a current liability as of December 31, 2019. The future conditional convertibility of the 2024 Notes will be monitored at each quarterly reporting date and analyzed dependent upon market prices of our common stock during the prescribed measurement periods.

Upon conversion, holders will receive the principal amount of their 2024 Notes and any excess conversion value, calculated based on the per share volume-weighted average price, or VWAP, for each of the 30 consecutive trading days during the observation period. For both the principal and excess conversion value, holders may receive cash, shares of our common stock or a combination of cash and shares of its common stock, at our option.

It is our intent and policy to settle conversions through combination settlement, which essentially involves repayment of an amount of cash equal to the “principal portion” and delivery of the “share amount” in excess of the principal portion in shares of common stock or cash. In general, for each $1,000 in principal, the “principal portion” of cash upon settlement is defined as the lesser of $1,000, and the conversion value during the 25-day observation period as described in the indenture for the notes. The conversion value is the sum of the daily conversion value which is the product of the effective conversion rate divided by 25 days and the daily VWAP of our common stock. The “share amount” is the cumulative “daily share amount” during the observation period, which is calculated by dividing the daily VWAP into the difference between the daily conversion value (i.e., conversion rate x daily VWAP) and $1,000.

The initial conversion rate for the 2024 Notes is 13.1711 shares of common stock per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $75.92 per share of our common stock. At the initial conversion rate, settlement of the 2024 Notes for shares of our common stock would approximate 6.8 million shares. The conversion rate will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. The initial conversion price of the 2024 Notes represented a premium of approximately 42.5% to the closing sale price of $53.28 per share of our common stock on the Nasdaq Global Select Market on April 26, 2017, the date we priced the private offering of the 2024 Notes.

In the event of conversion, holders would forgo all future interest payments, any unpaid accrued interest and the possibility of further stock price appreciation. Upon the receipt of conversion requests, the settlement of the 2024 Notes will be paid pursuant to the terms of the 2024 Indenture. In the event that all of the 2024 Notes are converted, we would be required to repay the $517.5 million in principal value and any conversion premium in any combination of cash and shares of its common stock (at the Company’s option).

On or after, but not prior to May 15, 2021, we may redeem for cash all or part of the 2024 Notes if the last reported sale price (as defined in the 2024 Indenture) of its common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading-day period ending on, and including, the trading day immediately before the date which we provide notice of redemption. The redemption price will equal the sum of (i) 100% of the principal amount

of the 2024 Notes being redeemed, plus (ii) accrued and unpaid interest, including additional interest, if any, to, but excluding, the redemption date. No sinking fund is provided for the 2024 Notes.

If we undergo a fundamental change, as defined in the 2024 Indenture, subject to certain conditions, holders of the 2024 Notes may require us to repurchase for cash all or part of their 2024 Notes at a repurchase price equal to 100% of the principal amount of the 2024 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if a ‘‘make-whole fundamental change’’ (as defined in the 2024 Indenture) occurs prior to January 15, 2024, we will, in certain circumstances, increase the conversion rate for a holder who elects to convert the 2024 Notes in connection with the make-whole fundamental change.

The 2024 Notes are our general unsecured obligations that rank senior in right of payment to all of our indebtedness that is expressly subordinated in right of payment to the 2024 Notes, and equal in right of payment to our unsecured indebtedness.

An entity must separately account for the liability and equity components of convertible debt instruments, such as the 2024 Notes, that may be settled entirely or partially in cash upon conversion in a manner that reflects the issuer’s economic interest cost. The liability component of the instrument was valued in a manner that reflects the market interest rate for a similar nonconvertible instrument at the date of issuance. The initial carrying value of the liability component of $368.3 million was calculated using a 7.5% assumed borrowing rate. The equity component of $149.2 million, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the 2024 Notes and is recorded in additional paid-in capital on the consolidated balance sheet at the issuance date. That equity component is treated as a discount on the liability component of the 2024 Notes, which is amortized over the seven-year term of the 2024 Notes using the effective interest rate method. The equity component is not re-measured as long as it continues to meet the conditions for equity classification. At December 31, 2019, the remaining period over which the discount on the liability component will be amortized was approximately 4.4 years.

We allocated the total transaction costs of approximately $14.7 million related to the issuance of the 2024 Notes to the liability and equity components of the 2024 Notes based on their relative values. Transaction costs attributable to the liability component are amortized to interest expense over the seven-year term of the 2024 Notes, and transaction costs attributable to the equity component are netted with the equity component in stockholders’ equity.

The 2024 Notes do not contain any financial or operating covenants or any restrictions on the payment of dividends, the issuance of other indebtedness or the issuance or repurchase of securities by the Company. The 2024 Indenture contains customary events of default with respect to the 2024 Notes, including that upon certain events of default, 100% of the principal and accrued and unpaid interest on the 2024 Notes will automatically become due and payable.

Convertible senior notes, net of discounts and deferred financing costs consisted of the following:

	December 31,
(in thousands)	2019			2018
Principal	$	517,500		$	517,500
Deferred financing costs		(6,937	)		(8,326	)
Debt discount, net		(101,756	)		(120,678	)
Net carrying amount	$	408,807		$	388,496

The 2024 Notes were recorded at the estimated value of a similar non-convertible instrument on the date of issuance and accretes to the face value of the 2024 Notes over their seven-year term. The fair value of the 2024 Notes, which was estimated utilizing market quotations from an over-the-counter trading market (Level 2), was $596.8 million at December 31, 2019 and $616.1 million at December 31, 2018.

Share-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2018	Dec. 31, 2016	May 31, 2011
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted	1,416,000	1,040,000	1,807,000
Stock options outstanding	6,107,000	5,746,000	6,356,000		6,112,000
Number of common stock available for future grant	6,800,000
Weighted-average fair values of stock options granted	$ 41.74	$ 43.42	$ 25.11
Weighted average remaining contractual term for stock options outstanding	6 years 8 months 12 days
Share-based compensation expense	$ 75,262,000	$ 58,068,000	$ 42,522,000
Number of stock options exercisable	4,000,000.0
Stock options exercisable, weighted average exercise price	$ 41.01
Stock options exercisable, weighted-average remaining contractual term	5 years 9 months 18 days
Stock options exercised in period intrinsic value	$ 64,300,000	117,000,000.0	61,400,000
Stock options intrinsic value of options outstanding	335,700,000
Stock options intrinsic value of options exercisable	268,200,000
Cash received from stock option exercises	$ 27,300,000	$ 29,500,000	$ 13,900,000
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, term	3 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, term	4 years
Share-based compensation, contractual term	10 years
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted	707,000	540,000	588,000
Share-based compensation expense	$ 30,400,000	$ 21,900,000	$ 13,900,000
Unrecognized compensation cost	$ 75,500,000
Stock vesting period	2 years 4 months 24 days
Total intrinsic value vested in period	$ 36,100,000	$ 35,500,000	$ 14,900,000
Intrinsic value outstanding	$ 147,200,000
Restricted stock units outstanding	1,368,000	1,133,000	1,080,000		883,000
Restricted Stock Units (RSUs) \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period	4 years
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, term	10 years
Share-based compensation expense	$ 36,500,000	$ 35,400,000	$ 28,200,000
Unrecognized compensation cost	$ 75,000,000.0
Stock vesting period	2 years 4 months 24 days
Stock Options \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period	3 years
Stock Options \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period	4 years
Performance-based RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted	0	200,000	0
Share-based compensation expense	$ 5,600,000	$ 0	$ 400,000
Unrecognized compensation cost	14,100,000
Intrinsic value outstanding	$ 35,500,000
Restricted stock units outstanding	300,000	300,000
Performance-based RSUs \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period	4 years	4 years
Performance-based RSUs \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period	5 years	5 years
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted	0	70,000	410,000
Stock vesting period		4 years	4 years
Stock options outstanding	211,000
Employees \| Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units granted	0	20,000	12,500
RSUs outstanding	211,000
Employees \| Restricted Stock Units (RSUs) \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period		3 years	3 years
Employees \| Restricted Stock Units (RSUs) \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock vesting period		4 years	4 years
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance				300,000
Number of shares purchased		0
Issuance of common stock for employee stock purchase plan	78,000
Share-based compensation expense	$ 2,700,000	$ 800,000
ESPP \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Discounted purchase price percentage of common stock authorized for issuance	85.00%
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance						21,000,000
Share Based Compensation Arrangement Award
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance	7,800,000
PRSUs Converted into Common Shares \| Performance-based RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value outstanding			$ 8,800,000

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Results of Operations

A summary of our quarterly results follows:

(in thousands, except per share data)	First Quarter			Second Quarter			Third Quarter		Fourth Quarter
Year Ended December 31, 2019:
Total revenues	$	138,403		$	183,580		$	222,094	$	244,010
Total operating expenses ⁽¹⁾	$	239,400		$	149,119		$	131,996	$	195,289
Net (loss) income ⁽¹⁾	$	(102,115	)	$	51,338		$	53,789	$	34,000
Net (loss) income per share, basic ⁽¹⁾	$	(1.12	)	$	0.56		$	0.59	$	0.37
Net (loss) income per share, diluted ⁽¹⁾	$	(1.12	)	$	0.54		$	0.56	$	0.35
Weighted average common shares outstanding, basic		91,056			91,389			91,859		92,182
Weighted average common shares outstanding, diluted		91,056			94,779			96,074		97,229
blank
Year Ended December 31, 2018:
Total revenues	$	71,086		$	96,905		$	151,757	$	131,492
Total operating expenses	$	108,533		$	98,757		$	97,434	$	109,621
Net (loss) income	$	(41,818	)	$	(5,913	)	$	50,764	$	18,078
Net (loss) income per share, basic	$	(0.47	)	$	(0.07	)	$	0.56	$	0.20
Net (loss) income per share, diluted	$	(0.47	)	$	(0.07	)	$	0.52	$	0.19
Weighted average common shares outstanding, basic		89,526			90,100			90,555		90,742
Weighted average common shares outstanding, diluted		89,526			90,100			96,798		95,724

Leases - Additional Information (Detail) $ in Thousands	1 Months Ended			12 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Aug. 31, 2019 ft² RenewalOption	Jun. 30, 2017	Dec. 31, 2007 USD ($) Building	Dec. 31, 2019 USD ($) Building	Dec. 31, 2018 USD ($)	May 31, 2018 USD ($) ft²	Dec. 31, 2008 USD ($)
Leases [Line Items]
Sale of facility and associated real property			$ 109,000
Mortgage debt retired			47,700
Cash received net of transaction costs and debt retirement			$ 61,000
Net deferred gain on real estate sale					$ 8,000		$ 39,100
Lease back transaction lease period			12 years
Number of building leased \| Building			2	1
Number of vacated buildings \| Building			1
Lessee operating lease term of contract	12 years
Number of times to renew the lease contract \| RenewalOption	2
Lease extension period	10 years
Lease description	The 2019 amendment includes two options to extend the term of the lease for a period of ten years each. We were not reasonably certain to exercise either of these options at lease commencement.
Restricted cash				$ 3,206	$ 5,477
Operating lease cost				8,100
Cash paid for cashflows from operating lease				7,700
Operating lease right of use asset				74,364
Operating lease, liability				$ 95,038
Operating lease, weighted average remaining lease term				11 years 2 months 12 days
Letter of Credit
Leases [Line Items]
Restricted cash				$ 3,000
Amended Lease Term
Leases [Line Items]
Lease expiration date	Jul. 31, 2031	Dec. 31, 2029
Office space area leased \| ft²	80,282
Lease Agreement
Leases [Line Items]
Office space area leased \| ft²						44,718
Lessee operating lease term of contract						10 years 10 months
Tenant improvement allowances						$ 4,200
Lease Agreement \| Letter of Credit
Leases [Line Items]
Restricted cash				$ 200		$ 1,000

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Components of Income Tax Expense for Continuing Operations

Components of income tax expense for continuing operations were as follows:

	Year Ended December 31,
(in thousands)	2019		2018			2017
Current:
Federal	$	—	$	(100	)	$	—
State		9,530		830			—
Total income tax expense	$	9,530	$	730		$	—

Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate

The provision for income taxes on earnings subject to income taxes differs from the statutory federal rate due to the following:

	December 31,
(in thousands)	2019			2018			2017
Federal income taxes at 21% for 2019 and 2018 and 35% for 2017	$	9,775		$	4,587		$	(49,889	)
State income tax, net of federal benefit		4,044			361			(4,013	)
Tax effect on non-deductible expenses		855			446			433
Branded prescription drug fee		3,707			—			—
Share-based compensation expense		(12,785	)		(9,778	)		(19,589	)
Officer compensation		3,068			915			2,163
Change in tax rate		(4,143	)		(198	)		154,415
Expired tax attributes		1,228			13,874			2,998
Research credits		(10,359	)		(13,526	)		(5,596	)
Change in valuation allowance		13,883			4,306			(79,966	)
Other		257			(257	)		(956	)
	$	9,530		$	730		$	—

Components of Deferred Tax Assets

	December 31,
(in thousands)	2019			2018
Deferred tax assets:
Net operating losses	$	181,300		$	223,800
Research and development credits		71,900			62,200
Capitalized research and development		28,000			34,800
Share-based compensation expense		22,900			17,300
Operating lease assets		23,300			100
Intangible assets		49,300			9,400
Other		18,500			19,100
Total deferred tax assets		395,200			366,700
Deferred tax liabilities:
Convertible senior notes		(24,100	)		(26,400	)
Operating lease liabilities		(18,200	)		—
Other		(6,900	)		(5,100	)
Total deferred tax liabilities		(49,200	)		(31,500	)
Net of deferred tax assets and liabilities		346,000			335,200
Valuation allowance		(346,000	)		(335,200	)
Net deferred tax assets	$	—		$	—

A summary of activity related to unrecognized tax benefits follows:

	Year Ended December 31,
(in thousands)	2019			2018			2017
Balance at January 1	$	54,775		$	37,403		$	34,112
Increases related to prior year tax positions		281			6,103			—
Increases related to current year tax positions		9,519			11,726			3,291
Expiration of the statute of limitations for the assessment of taxes		(657	)		(457	)		—
Balance at December 31	$	63,918		$	54,775		$	37,403

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income (loss)	$ 37,012	$ 21,111	$ (142,542)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Share-based compensation expense	75,262	58,068	42,522
Depreciation	7,452	4,024	2,400
Amortization of debt discount	18,922	17,552	10,937
Amortization of debt issuance costs	1,389	1,326	848
Net (accretion of discounts) amortization of premiums on investments	(1,965)	1,449	1,756
Change in fair value of restricted equity securities	12,987	0	0
Other, net	754	(409)	(1,445)
Changes in operating assets and liabilities:
Accounts receivable	(69,169)	(25,113)	(31,127)
Inventory	(6,424)	(3,524)	(1,024)
Accounts payable and accrued liabilities	53,955	24,223	27,338
Other changes in operating assets and liabilities, net	21,879	2,657	(3,994)
Net cash provided by (used in) operating activities	152,054	101,364	(94,331)
Cash Flows from Investing Activities:
Purchases of marketable securities	(797,169)	(545,962)	(583,408)
Sales and maturities of marketable securities	669,691	327,825	339,088
Purchase of restricted equity securities	(68,855)	0	0
Purchases of property and equipment	(14,748)	(24,812)	(6,940)
Proceeds from sales of property and equipment	8	34	7
Net cash used in investing activities	(211,073)	(242,915)	(251,253)
Cash Flows from Financing Activities:
Issuance of common stock	27,313	29,530	13,865
Proceeds from issuance of convertible senior notes, net	0	0	502,781
Net cash provided by financing activities	27,313	29,530	516,646
Change in cash and cash equivalents and restricted cash	(31,706)	(112,021)	171,062
Cash and cash equivalents and restricted cash at beginning of period	147,191	259,212	88,150
Cash and cash equivalents and restricted cash at end of period	115,485	147,191	259,212
Supplemental Disclosure:
Cash paid for interest	11,644	11,644	6,242
Cash paid for income taxes	507	0	0
Non-cash capital expenditures	$ 953	$ 2,318	$ 0

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 4. Fair Value Measurements

Investments measured at fair value on a recurring basis consisted of the following:

				Fair Value Measurements Using
(in thousands)	Carrying Value			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
December 31, 2019:
Classified as current assets:
Cash and money market funds	$	112,279		$	112,279		$	—	$	—
Commercial paper		144,472			—			144,472		—
Securities of government-sponsored entities		142,773			—			142,773		—
Corporate debt securities		271,000			—			271,000		—
blank		670,524			112,279			558,245		—
Classified as long-term assets:
Certificates of deposit		3,206			3,206			—		—
Securities of government-sponsored entities		48,708			—			48,708		—
Corporate debt securities		250,946			—			250,946		—
Restricted equity securities		55,868			—			—		55,868
blank		1,029,252			115,485			857,899		55,868
Less cash and cash equivalents and restricted cash		(115,485	)		(115,485	)		—		—
Total investments	$	913,767		$	—		$	857,899	$	55,868
blank
December 31, 2018:
Classified as current assets:
Cash and money market funds	$	141,714		$	141,714		$	—	$	—
Commercial paper		94,572			—			94,572		—
Securities of government-sponsored entities		20,840			—			20,840		—
Corporate debt securities		393,787			—			393,787		—
blank		650,913			141,714			509,199		—
Classified as long-term assets:
Cash and money market funds		1,500			1,500			—		—
Certificates of deposit		3,977			3,977			—		—
Securities of government-sponsored entities		64,837			—			64,837		—
Corporate debt securities		151,191			—			151,191		—
blank		872,418			147,191			725,227		—
Less cash and cash equivalents and restricted cash		(147,191	)		(147,191	)		—		—
Total investments	$	725,227		$	—		$	725,227	$	—

A reconciliation of restricted equity securities measured at fair value on a recurring basis follows.

(in thousands)
Balance at December 31, 2018	$	—
Investments in restricted equity securities		68,855
Net unrealized loss recognized on restricted equity securities during the period		(12,987)
Balance at December 31, 2019	$	55,868

- Definition

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

+ References + Details

Convertible Senior Notes - Additional Information (Detail) $ / shares in Units, shares in Millions		12 Months Ended
	May 02, 2017 USD ($) d $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Convertible senior notes principal amount		$ 517,500,000	$ 517,500,000
Proceeds from Senior Convertible Notes		$ 0	0	$ 502,781,000
2.25% Convertible Senior Notes due 2024
Debt Instrument [Line Items]
Convertible senior notes principal amount	$ 517,500,000
Convertible senior notes interest percentage	2.25%
Convertible senior notes convertible latest date	May 15, 2024
Proceeds from Senior Convertible Notes	$ 502,800,000
Threshold common stock trading days \| d	20
Threshold consecutive common stock trading days \| d	30
Threshold percentage of common stock price trigger	130.00%
Debt instrument conversion obligation number of consecutive business days after consecutive trading day period	5 days
Principal amount on conversion rate	$ 1,000
Minimum percentage of common stock price trigger	98.00%
Debt instrument convertible trading days during observation period	30 days
Conversion Observation Period	25 days
Debt instrument conversion value description	The conversion value is the sum of the daily conversion value which is the product of the effective conversion rate divided by 25 days and the daily VWAP of our common stock.
Debt instrument conversion share amount description	The “share amount” is the cumulative “daily share amount” during the observation period, which is calculated by dividing the daily VWAP into the difference between the daily conversion value (i.e., conversion rate x daily VWAP) and $1,000.
Convertible senior notes convertible in to shares	0.00131711
Convertible senior notes conversion price \| $ / shares	$ 75.92
Shares issued to settle notes at initial conversion rate \| shares	6.8
Market Price of Common stock \| $ / shares	$ 53.28
Convertible senior note premium	42.50%
Convertible senior notes redemption rate	100.00%
Convertible senior note carrying value of the liability component	$ 368,300,000
Convertible senior note assumed borrowing rate	7.50%
Convertible senior note carrying value of the equity component	$ 149,200,000
Convertible senior notes term	7 years
Discount on liability component, remaining amortization period		4 years 4 months 24 days
Transaction cost related to issuance of convertible senior note	$ 14,700,000
Debt instrument events of default percentage of principal and accrued and unpaid interest due and payable upon default	100.00%
Convertible senior notes fair value		$ 596,800,000	$ 616,100,000

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands, shares in Millions		12 Months Ended
	May 02, 2017 shares	Dec. 31, 2019 USD ($) Site Customer shares	Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($) Customer	Jan. 01, 2019 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Other-than-temporary Impairment		$ 0	$ 0
Transfers between levels in the fair value hierarchy		0	0
Depreciation		7,452	$ 4,024	$ 2,400
Right-of-use (ROU) assets		74,364
Operating lease liabilities		$ 95,038
ASU 2016-02
Organization And Summary Of Significant Accounting Policies [Line Items]
Right-of-use (ROU) assets					$ 50,000
Operating lease liabilities					70,900
Derecognition of deferred rent for certain lease incentives received					20,900
Recognition of Deferred Gain on Sale of Real Estate \| ASU 2016-02
Organization And Summary Of Significant Accounting Policies [Line Items]
Deferred gain on sale of real estate as cumulative-effect adjustment to equity					$ 8,000
2.25% Convertible Senior Notes due 2024
Organization And Summary Of Significant Accounting Policies [Line Items]
Shares issued to settle notes at initial conversion rate \| shares	6.8
Performance-based RSUs
Organization And Summary Of Significant Accounting Policies [Line Items]
Share equivalents excluded from computation of earnings per share \| shares		0.3
ESPP
Organization And Summary Of Significant Accounting Policies [Line Items]
Purchase period		6 months
Customer Concentration Risk \| Accounts Receivable
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of customers \| Customer		2	3	3
Customer Concentration Risk \| Sales Revenue, Goods, Net
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of customers \| Customer		2	3	3
Percentage of product revenue		86.00%	93.00%	93.00%
Ingrezza
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of separate commercial production sites \| Site		2
Advertising costs		$ 40,600	$ 20,500	$ 10,100
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average estimated useful life of equipment		3 years
Requisite service period of award		3 years
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average estimated useful life of equipment		7 years
Requisite service period of award		4 years
In Process Research and Development
Organization And Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassifications			$ 4,800	$ 30,000

Other Balance Sheet Details

12 Months Ended

Dec. 31, 2019

Other Balance Sheet Details [Abstract]

Other Balance Sheet Details

Note 6. Other Balance Sheet Details

Inventory consisted of the following:

	December 31,
(in thousands)	2019		2018
Raw materials	$	14,148	$	7,855
Work in process		1,470		2,208
Finished goods		1,670		801
Total inventory	$	17,288	$	10,864

Property and equipment, net, consisted of the following:

	December 31,
(in thousands)	2019			2018
Tenant improvements	$	26,342		$	19,857
Scientific equipment		33,483			28,163
Computer equipment		12,460			11,152
Furniture and fixtures		3,188			2,968
blank		75,473			62,140
Less accumulated depreciation		(33,559	)		(28,271	)
Total property and equipment, net	$	41,914		$	33,869

Accounts payable and accrued liabilities consisted of the following:

	December 31,
(in thousands)	2019		2018
Accrued employee related costs	$	38,941	$	27,341
Revenue-related reserves for discounts and allowances		30,634		13,586
Accrued development costs		25,496		7,069
Accounts payable and other accrued liabilities		46,214		38,381
Total accounts payable and accrued liabilities	$	141,285	$	86,377

(in thousands)	December 31, 2019		December 31, 2018
Cash and cash equivalents	$	112,279	$	141,714
Restricted cash		3,206		5,477
Total cash, cash equivalents and restricted cash	$	115,485	$	147,191

Net Income (Loss) Per Share - Schedule of Net Income (Loss) Per Share (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Subsidiary Sale Of Stock [Line Items]

Net income (loss)

$ 34,000

^[1]

$ 53,789

^[1]

$ 51,338

^[1]

$ (102,115)

^[1]

$ 18,078

$ 50,764

$ (5,913)

$ (41,818)

$ 37,012

$ 21,111

$ (142,542)

Weighted average common shares outstanding, basic

92,182,000

91,859,000

91,389,000

91,056,000

90,742,000

90,555,000

90,100,000

89,526,000

91,627,000

90,235,000

88,089,000

Effect of dilutive securities:

2024 Notes

1,072,000

1,348,000

Weighted average common shares outstanding, diluted

97,229,000

96,074,000

94,779,000

91,056,000

95,724,000

96,798,000

90,100,000

89,526,000

95,732,000

95,386,000

88,089,000

Net income (loss) per share, basic

$ 0.37

^[1]

$ 0.59

^[1]

$ 0.56

^[1]

$ (1.12)

^[1]

$ 0.20

$ 0.56

$ (0.07)

$ (0.47)

$ 0.40

$ 0.23

$ (1.62)

Net income (loss) per share, diluted

$ 0.35

^[1]

$ 0.56

^[1]

$ 0.54

^[1]

$ (1.12)

^[1]

$ 0.19

$ 0.52

$ (0.07)

$ (0.47)

$ 0.39

$ 0.22

$ (1.62)

Stocks Options

Effect of dilutive securities:

Effect of dilutive securities

2,559,000

3,228,000

Restricted Stock

Effect of dilutive securities:

Effect of dilutive securities

449,000

564,000

ESPP

Effect of dilutive securities:

Effect of dilutive securities

25,000

11,000

[1]

Net Income (Loss) Per Share - Schedule of Anti-Dilutive Shares Excluded from Diluted Per Share Amounts (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options Restricted Stock and Convertible Senior Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from diluted per share amounts	2,144	887	7,436

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Deferred tax assets, valuation allowance	$ 346,000	$ 335,200
Research and development tax credit carry forwards	$ 71,900	62,200
Percentage of uncertain tax positions likelihood of being sustained	50.00%
Increases related to current year tax positions	$ 9,519	$ 11,726	$ 3,291
Unrecognized tax benefits that would affect effective tax rate	57,900
Federal
Income Taxes [Line Items]
Operating loss carry forward, net	$ 816,200
Operating loss carry forward beginning expiration year	2024
Research and development tax credit carry forwards	$ 73,200
Federal \| R&D
Income Taxes [Line Items]
Tax credit carry forwards beginning expiration year	2019
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carry forward, net	$ 359,800
Research and development tax credit carry forwards	$ 47,500
State and Local Jurisdiction \| California
Income Taxes [Line Items]
Operating loss carry forward beginning expiration year	2028
State and Local Jurisdiction \| Other States
Income Taxes [Line Items]
Operating loss carry forward beginning expiration year	2026

Gross Unrealized Losses and Fair Value Available-For-Sale Debt securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	$ 234,124	$ 331,622
Less Than 12 Months, Unrealized Losses	(127)	(792)
12 Months or Greater, Estimated Fair Value	0	245,745
12 Months or Greater, Unrealized Losses	0	(1,376)
Total Estimated Fair Value	234,124	577,367
Total Unrealized Losses	(127)	(2,168)
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	33,070	51,927
Less Than 12 Months, Unrealized Losses	(15)	(45)
12 Months or Greater, Estimated Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total Estimated Fair Value	33,070	51,927
Total Unrealized Losses	(15)	(45)
Corporate debt securities
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	186,052	274,696
Less Than 12 Months, Unrealized Losses	(110)	(746)
12 Months or Greater, Estimated Fair Value	0	234,798
12 Months or Greater, Unrealized Losses	0	(1,321)
Total Estimated Fair Value	186,052	509,494
Total Unrealized Losses	(110)	(2,067)
Securities of government-sponsored entities
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	15,002	4,999
Less Than 12 Months, Unrealized Losses	(2)	(1)
12 Months or Greater, Estimated Fair Value	0	10,947
12 Months or Greater, Unrealized Losses	0	(55)
Total Estimated Fair Value	15,002	15,946
Total Unrealized Losses	$ (2)	$ (56)

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
Common stock, shares authorized	220,000,000	220,000,000
Common stock, shares issued	92,272,000	90,797,000
Common stock, shares outstanding	92,272,000	90,797,000

Leases - Summary of Minimum Lease Payments for Operating Lease Liabilities (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 8,558
2021	10,578
2022	10,900
2023	11,232
2024	11,574
Thereafter	91,271
Total operating lease payments	134,681
Less accreted interest	(39,643)
Operating Lease, Liability	95,038
Less current operating lease liabilities	(8,282)
Noncurrent operating lease liabilities	$ 86,756

Other Balance Sheet Details - Summary of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Other Balance Sheet Details [Abstract]
Raw materials	$ 14,148	$ 7,855
Work in process	1,470	2,208
Finished goods	1,670	801
Total inventory	$ 17,288	$ 10,864

Other Balance Sheet Details - Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Other Balance Sheet Details [Abstract]
Accrued employee related costs	$ 38,941	$ 27,341
Revenue-related reserves for discounts and allowances	30,634	13,586
Accrued development costs	25,496	7,069
Accounts payable and other accrued liabilities	46,214	38,381
Total accounts payable and accrued liabilities	$ 141,285	$ 86,377

Convertible Senior Notes - Convertible Senior Notes, Net of Discounts and Deferred Financing Costs (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Principal	$ 517,500	$ 517,500
Deferred financing costs	(6,937)	(8,326)
Debt discount, net	(101,756)	(120,678)
Net carrying amount	$ 408,807	$ 388,496

Leases - Summary of Minimum Lease Payments for Operating Lease Liabilities (Parenthetical) (Detail) $ in Millions	Dec. 31, 2019 USD ($)
Leases [Abstract]
Non-cancelable future minimum lease payments for operating leases that have not yet commenced	$ 28.3

Other Balance Sheet Details - Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 75,473	$ 62,140
Less accumulated depreciation	(33,559)	(28,271)
Total property and equipment, net	41,914	33,869
Tenant improvements
Property, Plant and Equipment [Line Items]
Property and equipment	26,342	19,857
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	3,188	2,968
Scientific equipment
Property, Plant and Equipment [Line Items]
Property and equipment	33,483	28,163
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	$ 12,460	$ 11,152

Available-For-Sale Debt Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Investments [Line Items]
Marketable securities	$ 857,899	$ 725,227
Commercial paper
Schedule Of Investments [Line Items]
Marketable securities	144,472	94,572
Corporate debt securities
Schedule Of Investments [Line Items]
Marketable securities	521,946	544,978
Securities of government-sponsored entities
Schedule Of Investments [Line Items]
Marketable securities	$ 191,481	$ 85,677

Components of Income Tax Expense for Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal		$ (100)
State	$ 9,530	830
Total income tax expense	$ 9,530	$ 730

Commitments and Contingencies - Additional Information (Detail) $ in Billions	Dec. 31, 2019 USD ($)
Development and Regulatory Milestone Payments
Commitment And Contingencies [Line Items]
Potential milestone payments	$ 4.9