Neurocrine Biosciences (NBIX) 10-Q 3 Aug 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 28, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	0-22705
Entity Registrant Name	NEUROCRINE BIOSCIENCES, INC.
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
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	NBIX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
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		93,254,872
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000914475
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 415.1	$ 112.3
Debt securities available-for-sale, at fair value (amortized cost $530.3 million at June 30, 2020 and $557.3 million at December 31, 2019)	533.2	558.2
Accounts receivable	148.4	126.6
Inventories	22	17.3
Other current assets	27.5	16.6
Total current assets	1,146.2	831
Debt securities available-for-sale, at fair value (amortized cost $193.5 million at June 30, 2020 and $299.3 million at December 31, 2019)	195.2	299.7
Right-of-use assets	72.1	74.3
Equity securities	50.7	55.9
Property and equipment, net	44.6	41.9
Restricted cash	3.2	3.2
Other long-term assets	3.6	0
Total assets	1,515.6	1,306
Current liabilities:
Accounts payable and accrued liabilities	137.1	141.3
Convertible senior notes	419.5	408.8
Other current liabilities	16.4	15.2
Total current liabilities	573	565.3
Operating lease liabilities	84.3	86.7
Other long-term liabilities	27.1	17.1
Total liabilities	684.4	669.1
Stockholders’ equity:
Preferred stock, $0.001 par value; 5.0 shares authorized; no shares issued and outstanding at June 30, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value; 220.0 shares authorized; issued and outstanding shares were 93.2 at June 30, 2020 and 92.3 at December 31, 2019	0.1	0.1
Additional paid-in capital	1,842.2	1,768.1
Accumulated other comprehensive income	4.6	1.4
Accumulated deficit	(1,015.7)	(1,132.7)
Total stockholders’ equity	831.2	636.9
Total liabilities and stockholders’ equity	$ 1,515.6	$ 1,306

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Amortized cost, current	$ 530.3	$ 557.3
Amortized cost, noncurrent	$ 193.5	$ 299.3
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	220,000,000	220,000,000
Common stock, shares issued (in shares)	93,200,000	92,300,000
Common stock, shares outstanding (in shares)	93,200,000	92,300,000

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Operations And Comprehensive Income (Loss) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Total revenues	$ 302.4	$ 183.5	$ 539.5	$ 321.9
Operating expenses:
Cost of sales	2.4	1.6	4.5	2.7
Research and development	80.9	61.7	139.2	99.4
Acquired in-process research and development	46	5	46	118.1
Selling, general and administrative	96.5	80.8	214.3	168.3
Total operating expenses	225.8	149.1	404	388.5
Operating income (loss)	76.6	34.4	135.5	(66.6)
Other income (expense):
Interest expense	(8.3)	(7.9)	(16.5)	(15.8)
Unrealized gain (loss) on equity securities	11.3	21	(5.2)	22.7
Investment income and other, net	3.6	4.6	8.3	9.2
Total other income (expense), net	6.6	17.7	(13.4)	16.1
Income (loss) before provision for income taxes	83.2	52.1	122.1	(50.5)
Provision for income taxes	3.6	0.8	5.1	0.3
Net income (loss)	79.6	51.3	117	(50.8)
Unrealized gain on debt securities available-for-sale, net of tax	6	0.9	3.2	2.6
Comprehensive income (loss)	$ 85.6	$ 52.2	$ 120.2	$ (48.2)
Net income (loss) per share, basic (in USD per share)	$ 0.86	$ 0.56	$ 1.26	$ (0.56)
Net income (loss) per share, diluted (in USD per share)	$ 0.81	$ 0.54	$ 1.20	$ (0.56)
Weighted average common shares outstanding, basic (in shares)	93	91.4	92.8	91.2
Weighted average common shares outstanding, diluted (in shares)	98.2	94.8	97.6	91.2
Product sales, net
Revenues:
Total revenues	$ 267.6	$ 180.5	$ 498.7	$ 316.9
Collaboration revenue
Revenues:
Total revenues	$ 34.8	$ 3	$ 40.8	$ 5

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated DeficitCumulative-effect adjustment to equity due to adoption of ASU 2016-02
Beginning Balance (in shares) at Dec. 31, 2018		90.8
Beginning Balance at Dec. 31, 2018	$ 480.8	$ 0.1	$ 1,660.4	$ (2)	$ (1,177.7)	$ 8
Net income (loss)	(50.8)				(50.8)
Unrealized gain on debt securities available-for-sale, net of tax	2.6			2.6
Share-based compensation expense	33.7		33.7
Issuance of common stock for vested restricted stock units (in shares)		0.4
Issuance of common stock for stock option exercises (in shares)		0.3
Issuance of common stock for stock options	6.9		6.9
Issuance of common stock for employee stock purchase plan	2.5		2.5
Ending Balance (in shares) at Jun. 30, 2019		91.5
Ending Balance at Jun. 30, 2019	483.7	$ 0.1	1,703.5	0.6	(1,220.5)
Beginning Balance (in shares) at Mar. 31, 2019		91.3
Beginning Balance at Mar. 31, 2019	409.3	$ 0.1	1,681.3	(0.3)	(1,271.8)
Net income (loss)	51.3				51.3
Unrealized gain on debt securities available-for-sale, net of tax	0.9			0.9
Share-based compensation expense	17.9		17.9
Issuance of common stock for stock option exercises (in shares)		0.2
Issuance of common stock for stock options	4.3		4.3
Ending Balance (in shares) at Jun. 30, 2019		91.5
Ending Balance at Jun. 30, 2019	483.7	$ 0.1	1,703.5	0.6	(1,220.5)
Beginning Balance (in shares) at Dec. 31, 2019		92.3
Beginning Balance at Dec. 31, 2019	636.9	$ 0.1	1,768.1	1.4	(1,132.7)
Net income (loss)	117				117
Unrealized gain on debt securities available-for-sale, net of tax	3.2			3.2
Share-based compensation expense	52.3		52.3
Issuance of common stock for vested restricted stock units (in shares)		0.5
Issuance of common stock for stock option exercises (in shares)		0.4
Issuance of common stock for stock options	19.1		19.1
Issuance of common stock for employee stock purchase plan	2.7		2.7
Ending Balance (in shares) at Jun. 30, 2020		93.2
Ending Balance at Jun. 30, 2020	831.2	$ 0.1	1,842.2	4.6	(1,015.7)
Beginning Balance (in shares) at Mar. 31, 2020		92.8
Beginning Balance at Mar. 31, 2020	700.3	$ 0.1	1,796.9	(1.4)	(1,095.3)
Net income (loss)	79.6				79.6
Unrealized gain on debt securities available-for-sale, net of tax	6			6
Share-based compensation expense	29.5		29.5
Issuance of common stock for vested restricted stock units (in shares)		0.1
Issuance of common stock for stock option exercises (in shares)		0.3
Issuance of common stock for stock options	15.8		15.8
Ending Balance (in shares) at Jun. 30, 2020		93.2
Ending Balance at Jun. 30, 2020	$ 831.2	$ 0.1	$ 1,842.2	$ 4.6	$ (1,015.7)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ 117	$ (50.8)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Share-based compensation expense	52.3	33.7
Depreciation	4.2	3.4
Amortization of debt discount	10	9.3
Amortization of debt issuance costs	0.7	0.7
Change in fair value of equity security investments	5.2	(22.7)
Other	0.7	(0.6)
Change in operating assets and liabilities:
Accounts receivable	(21.8)	(39.1)
Inventory	(4.7)	(1.2)
Accounts payable and accrued liabilities	(5.1)	7.7
Other assets and liabilities, net	(1.4)	11.3
Net cash provided by (used in) operating activities	157.1	(48.3)
Cash Flows from Investing Activities:
Purchases of debt securities available-for-sale	(288.6)	(235.9)
Sales and maturities of debt securities available-for-sale	421.2	339.7
Purchases of equity securities	0	(54.7)
Purchases of property and equipment	(6)	(8.4)
Net cash provided by investing activities	126.6	40.7
Cash Flows from Financing Activities:
Issuance of common stock	19.1	6.9
Net cash provided by financing activities	19.1	6.9
Change in cash and cash equivalents and restricted cash	302.8	(0.7)
Cash and cash equivalents and restricted cash at beginning of period	115.5	147.2
Cash and cash equivalents and restricted cash at end of period	418.3	146.5
Supplemental Disclosure:
Non-cash capital expenditures	0.9	0.9
Cash paid for interest	5.8	5.8
Cash paid for income taxes	$ 0	$ 0.4

Organization and Significant Ac

Organization and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	Organization and Significant Accounting Policies Description of Business . Neurocrine Biosciences, Inc., or Neurocrine Biosciences, 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 Biosciences. 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, or US, our first US Food and Drug Administration, or FDA, approved product. In April 2017, we received FDA approval of our first marketed product, INGREZZA, for the treatment of adults with tardive dyskinesia, or TD. Shortly after receiving FDA approval, we began commercializing INGREZZA in the US 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 receive royalties at tiered percentage rates on any net sales of ORILISSA. In April 2020, we received FDA approval for ONGENTYS ® (opicapone) as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients. FDA approval for ONGENTYS for Parkinson’s disease triggered a milestone payment of $20.0 million, which was expensed as research and development, or R&D, in the second quarter of 2020. In May 2020, AbbVie received approval from the FDA for ORIAHNN TM (elagolix) for the management of heavy menstrual bleeding associated with uterine fibroids in pre-menopausal women. FDA approval for ORIAHNN for uterine fibroids resulted in the achievement of a $30.0 million regulatory milestone, which was recognized as collaboration revenue in the second quarter of 2020. We are entitled to receive royalties at tiered percentage rates on any net sales of ORIAHNN. Our late-stage pipeline includes crinecerfont (NBI-74788) for the treatment of congenital adrenal hyperplasia, or CAH, in adult patients, 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 candidate for advanced Parkinson’s disease is partnered with Voyager Therapeutics, Inc., or Voyager. Our early-stage clinical pipeline includes crinecerfont for the treatment of CAH in pediatric patients, elagolix for the treatment of polycystic ovary syndrome, or PCOS, in women, NBI-921352 (XEN901), a clinical-stage candidate with potential in epilepsy, and NBI-827104 (ACT-709478), a T-type calcium channel blocker in clinical development for the treatment of a rare pediatric epilepsy. Our product candidate for PCOS is partnered with AbbVie. In May 2020, we entered into a collaboration and licensing agreement with Idorsia Pharmaceuticals Ltd, or Idorsia. In connection with the agreement, we paid Idorsia $45.0 million upfront to gain a license to NBI-827104 (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 agreement includes a research collaboration to discover and identify up to two additional novel T-type calcium channel blockers as development candidates. In June 2020, we entered into an exclusive license agreement with Takeda Pharmaceutical Company Limited, or Takeda, to develop and commercialize certain compounds in Takeda’s early to mid-stage psychiatry pipeline. The agreement became effective in July 2020, upon expiration of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. In connection with the agreement, we paid Takeda $120.0 million upfront (less an earnest money deposit paid by us to Takeda in the first quarter of 2020) to gain an exclusive license to seven of Takeda’s pipeline programs, including three clinical-stage assets for schizophrenia, treatment-resistant depression, and anhedonia. The collaboration also includes a cost-sharing arrangement for associated collaboration activities. Basis of Presentation . The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or GAAP, for interim financial information and with the instructions of the Securities and Exchange Commission, or SEC, on Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, the condensed consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of our financial position and of the results of operations and cash flows for the periods presented. The accompanying unaudited condensed consolidated financial statements include the accounts of Neurocrine Biosciences and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2019, included in our Annual Report on Form 10-K, or the 2019 Form 10-K, filed with the SEC. The results of operations for the interim period shown in this report are not necessarily indicative of the results that may be expected for any other interim period or the full year. The condensed consolidated balance sheet at December 31, 2019, has been derived from the audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. There were no significant changes to our significant accounting policies as disclosed in the 2019 Form 10-K, except as set forth below. Debt Securities. Debt securities consist of investments in certificates of deposit, corporate debt securities, and securities of government-sponsored entities. We classify debt securities as available-for-sale. Debt securities available-for-sale are recorded at fair value, with unrealized gains and losses included in other comprehensive income or loss, net of tax. We exclude accrued interest from both the fair value and amortized cost basis of debt securities. A debt security is placed on nonaccrual status at the time any principal or interest payments become 90 days delinquent. Interest accrued but not received for a debt security placed on nonaccrual status is reversed against interest income. Interest income includes amortization of purchase premium or discount. Premiums and discounts on debt securities are amortized using the effective interest rate method. Gains and losses on sales of debt securities are recorded on the trade date in investment income and other, net, and determined using the specific identification method. Allowance for Credit Losses. For debt securities available-for-sale in an unrealized loss position, we first assess whether we intend to sell, or it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For debt securities available-for-sale that do not meet the aforementioned criteria, we evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the extent to which fair value is less than amortized cost, any changes in interest rates, and any changes to the rating of the security by a rating agency, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income or loss, as applicable. Accrued interest receivables on debt securities available-for-sale totaled $3.7 million at June 30, 2020. We do not measure an allowance for credit losses for accrued interest receivables. For the purposes of identifying and measuring an impairment, accrued interest is excluded from both the fair value and amortized cost basis of the debt security. Uncollectible accrued interest receivables associated with an impaired debt security are reversed against interest income upon identification of the impairment. No accrued interest receivables were written off during the six months ended June 30, 2020. Fair Value of Financial Instruments. We record cash equivalents, debt securities available-for-sale and 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 fair value hierarchy consists of the following 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. Investments in debt securities available-for-sale are classified as Level 2 and carried at fair value. We estimate the fair value of debt securities available-for-sale by utilizing third-party pricing services. These pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. Such inputs include market pricing based on real-time trade data for similar instruments, issuer credit spreads, benchmark yields, broker/dealer quotes and other observable inputs. We validate valuations obtained from third-party pricing services by understanding the models used, obtaining market values from other pricing sources, and analyzing data in certain instances. Investments in equity securities of certain companies that are subject to holding period restrictions longer than one year are classified as Level 3 and carried at fair value using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the stock price volatility, which is based on the historical volatility of similar companies, and the discount for lack of marketability related to the term of the restrictions. The carrying amounts of accounts receivable and accounts payable and accrued liabilities approximate their fair values due to their short-term maturities. Recently Adopted Accounting Pronouncements. ASU 2016-13. On January 1, 2020, we adopted Accounting Standards Update, or ASU, 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, using the modified retrospective transition method. For debt securities available-for-sale, the standard requires an investor to determine whether a decline in the fair value below the amortized cost basis of the investment is due to credit-related factors. Credit-related impairment is recognized as an allowance for credit loss on the balance sheet with a corresponding adjustment to earnings. Credit losses are limited to the amount by which the investment’s amortized cost basis exceeds its fair value and may be subsequently reversed if conditions change. Any impairment that is not credit related is recognized in other comprehensive income or loss, as applicable, net of applicable taxes. The adoption of ASU 2016-13 did not result in a cumulative-effect adjustment to retained earnings. The comparative prior period information continues to be reported under the accounting standards in effect during those periods. Recently Issued Accounting Pronouncements. ASU 2019-12. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and amends existing guidance to improve consistent application of Topic 740. ASU 2019-12 is effective for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years, with early adoption permitted in any interim period for which financial statements have not yet been made available for issuance. We are currently evaluating the effect that ASU 2019-12 will have on our condensed consolidated financial statements and related disclosures.

Significant Collaboration and L

Significant Collaboration and Licensing Agreements	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Significant Collaboration and Licensing Agreements	Significant Collaboration and Licensing Agreements AbbVie. In June 2010, we entered into an exclusive worldwide collaboration with AbbVie to develop and commercialize elagolix and all next-generation gonadotropin-releasing factor antagonists for women’s and men’s health. AbbVie received approval of ORILISSA for the management of moderate to severe endometriosis pain in women from the FDA in July 2018 and Health Canada in October 2018. In May 2020, AbbVie received approval from the FDA for ORIAHNN for the management of heavy menstrual bleeding associated with uterine fibroids in pre-menopausal women. FDA approval for ORIAHNN for uterine fibroids resulted in the achievement of a $30.0 million regulatory milestone, which was recognized as collaboration revenue in the second quarter of 2020. Since inception of the agreement, we have recognized revenue of $75.0 million associated with the delivery of a technology license and existing know-how and $165.0 million associated with the achievement of certain development and regulatory milestones. Pursuant to the terms of the agreement, we may also be entitled to receive payments of up to $366.0 million upon the achievement of certain development, regulatory and commercial milestones. 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, Revenue from Contracts with Customers , 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. BIAL – Portela & Ca, S.A. In the first quarter of 2017, we entered into an exclusive license agreement with BIAL – Portela & Ca, S.A., or BIAL, for the development and commercialization of ONGENTYS for the treatment of human diseases and conditions, including Parkinson’s disease, in the US and Canada. In April 2020, we received FDA approval for ONGENTYS as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients. FDA approval for ONGENTYS for Parkinson’s disease triggered a milestone payment of $20.0 million, which was expensed as R&D in the second quarter of 2020. Pursuant to the terms of the agreement, BIAL may also be entitled to receive up to $75.0 million upon the achievement of certain commercial milestones. Under the terms of the agreement, we are responsible for the commercialization of ONGENTYS in the US and Canada. Further, we will rely on BIAL for the commercial supply of ONGENTYS. Upon our written request prior to the estimated expiration of the term 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. Upon commercialization of ONGENTYS, we will determine certain annual sales forecasts. In the event we fail to meet the minimum sales requirements for a particular year, we would be obligated to pay BIAL an amount equal to the difference between the actual net sales and minimum sales requirements for such year. Unless earlier terminated, 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. Either party may terminate the agreement 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 to submit an NDA for a licensed product by a specified date, in the event we fail to meet the minimum sales requirements for any two years, or under certain circumstances involving a change of control of Neurocrine Biosciences. Under certain circumstances where BIAL elects to terminate the agreement in connection with a change of control of Neurocrine Biosciences, BIAL would be obligated to pay us a termination fee. We may terminate the agreement at any time for any reason upon nine months’ written notice to BIAL. Voyager. In the first quarter of 2019, we entered into a collaboration and license agreement with Voyager, a clinical-stage gene therapy company. 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 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 receive payments of up to $1.7 billion upon the achievement of certain development, regulatory and commercial milestones, as well as receive royalties on the 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 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 second 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 US 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. 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 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 Pharmaceuticals Inc., or Xenon, to identify, research, and develop sodium channel inhibitors, including clinical candidate NBI-921352 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 US. 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 US. 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 receive payments of up to $1.7 billion upon the achievement of certain development, regulatory and commercial milestones, as well as receive royalties on the 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 . In March 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. In the first six months of 2020, we recognized revenue of $1.3 million in connection with the ongoing KINECT-HD study, a placebo-controlled Phase III study of valbenazine in adult Huntington’s disease patients with chorea. In accordance with our continuing performance obligations, $8.1 million of the $30.0 million upfront payment received from MTPC in connection with the agreement is being deferred and will be recognized as revenue over the study period using an input method according to costs incurred to-date relative to estimated total costs associated with the study. Since inception of the agreement, we have recognized revenue of $19.8 million associated with the delivery of a technology license and existing know-how, $15.0 million associated with the achievement of a certain development milestones, and $2.1 million associated with our performance of the ongoing KINECT-HD study. Pursuant to the terms of the agreement, we may also be entitled to receive payments of up to $70.0 million upon the achievement of certain regulatory and commercial milestones, receive payments for the manufacture of certain pharmaceutical products, as well as receive royalties on the net sales of collaboration products 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 payment received 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. Idorsia. In January 2020, we announced a collaboration and optional licensing agreement with Idorsia, granting us an option to license NBI-827104, 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 included a research collaboration to discover and identify up to two additional novel T-type calcium channel blockers as development candidates. In May 2020, we exercised the option to license the global rights to NBI-827104. In connection with the exercise of the option, we paid Idorsia $45.0 million upfront, which was expensed as IPR&D in the second quarter of 2020. Further, as part of the research collaboration, we provided Idorsia with an incremental $7.2 million in funding, which was recorded as a prepaid asset to be expensed over the two-year research collaboration term. Pursuant to the terms of the agreement, upon the achievement of certain development and regulatory milestones, Idorsia may be entitled to receive payments of up to $365.0 million with respect to NBI-827104 and up to $620.0 million with respect to the development candidates. In addition, Idorsia may also be entitled to receive payments of up to $750.0 million upon the achievement of certain commercial milestones, as well as receive royalties on the net sales of any collaboration product. Further, we will be responsible for all manufacturing, development and commercialization costs of any collaboration product. We may terminate the collaboration and licensing agreement, in its entirety or with respect to a particular compound or development candidate, by providing 90 days’ written notice to Idorsia. Further, in the event a party commits a material breach and fails to cure such material breach within 90 days after receiving written notice thereof, the non-breaching party may terminate the agreement in its entirety immediately upon written notice to the breaching party.

Debt Securities

Debt Securities	6 Months Ended
	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Debt Securities	Debt Securities The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive loss, allowance for credit losses, and fair value of debt securities available-for-sale at June 30, 2020, aggregated by major security type and contractual maturity: (in millions) Contractual Amortized Unrealized Unrealized Allowance for Credit Losses Fair Commercial paper Within 1 year $ 140.0 $ 0.1 $ — — $ 140.1 Corporate debt securities Within 1 year 287.8 2.0 — — 289.8 Securities of government-sponsored entities Within 1 year 102.5 0.8 — — 103.3 $ 530.3 $ 2.9 $ — $ — $ 533.2 Corporate debt securities 1 to 2 years $ 173.5 $ 1.7 $ — — $ 175.2 Securities of government-sponsored entities 1 to 2 years 20.0 — — — 20.0 $ 193.5 $ 1.7 $ — $ — $ 195.2 The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive income, and fair value of debt securities available-for-sale at December 31, 2019, aggregated by major security type and contractual maturity: (in millions) Contractual Amortized Unrealized Unrealized Fair Commercial paper Within 1 year $ 144.5 — — $ 144.5 Corporate debt securities Within 1 year 270.5 0.5 — 271.0 Securities of government-sponsored entities Within 1 year 142.3 0.4 — 142.7 $ 557.3 $ 0.9 $ — $ 558.2 Corporate debt securities 1 to 2 years $ 250.5 $ 0.5 $ (0.1) $ 250.9 Securities of government-sponsored entities 1 to 2 years 48.8 — — 48.8 $ 299.3 $ 0.5 $ (0.1) $ 299.7 At June 30, 2020, debt securities available-for-sale in an unrealized loss position for which an allowance for credit losses had not been recorded were not significant. Further, at June 30, 2020, our security portfolio consisted of 158 securities related to investments in debt securities available-for-sale, of which 17 securities were in an unrealized loss position. Our investments in commercial paper, corporate debt securities and securities of government-sponsored entities are of high credit quality (rated A1, A- and AA+ or higher, respectively). Unrealized losses on these investments were primarily due to changes in interest rates. We do not intend to sell these investments and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost basis. The following table summarizes debt securities available-for-sale in an unrealized loss position at December 31, 2019, aggregated by major security type and length of time in a continuous unrealized loss position: Less Than 12 Months 12 Months or Longer Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Corporate debt securities $ 186.1 $ (0.1) $ — $ — $ 186.1 $ (0.1)

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Investments at June 30, 2020, which were measured at fair value on a recurring basis, consisted of the following: Fair Value Measurements Using (in millions) Fair Value Level 1 Level 2 Level 3 Cash and cash equivalents: Cash and money market funds $ 415.1 $ 415.1 $ — $ — Total cash and cash equivalents 415.1 415.1 — — Restricted cash: Certificates of deposit 3.2 3.2 — — Total restricted cash 3.2 3.2 — — Debt securities available-for-sale: Commercial paper 140.1 — 140.1 — Corporate debt securities 465.0 — 465.0 — Securities of government-sponsored entities 123.3 — 123.3 — Total debt securities available-for-sale 728.4 — 728.4 — Equity securities: Equity securities–biotechnology industry 50.7 — — 50.7 Total equity securities 50.7 — — 50.7 Total recurring fair value measurements $ 1,197.4 $ 418.3 $ 728.4 $ 50.7 Investments at December 31, 2019, which were measured at fair value on a recurring basis, consisted of the following: Fair Value Measurements Using (in millions) Fair Value Level 1 Level 2 Level 3 Cash and cash equivalents: Cash and money market funds $ 112.3 $ 112.3 — — Total cash and cash equivalents 112.3 112.3 — — Restricted cash: Certificates of deposit 3.2 3.2 — — Total restricted cash 3.2 3.2 — — Debt securities available-for-sale: Commercial paper 144.5 — 144.5 — Corporate debt securities 521.9 — 521.9 — Securities of government-sponsored entities 191.5 — 191.5 — Total debt securities available-for-sale 857.9 — 857.9 — Equity securities: Equity securities–biotechnology industry 55.9 — — 55.9 Total equity securities 55.9 — — 55.9 Total recurring fair value measurements $ 1,029.3 $ 115.5 $ 857.9 $ 55.9 The following table presents a reconciliation of equity security investments, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Three Months Ended Six Months Ended (in millions) 2020 2019 2020 2019 Balance at beginning of period $ 39.4 $ 56.4 $ 55.9 $ — Purchases — — — 54.7 Unrealized gains (losses) included in earnings 11.3 21.0 (5.2) 22.7 Balance at end of period $ 50.7 $ 77.4 $ 50.7 $ 77.4 At June 30, 2020, the discount for lack of marketability used in the valuation analysis of equity securities ranged from 17.5% to 31.5% (weighted average of 27.5%). The discount for lack of marketability was weighted by the relative fair value of the

Inventories

Inventories	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following: (in millions) June 30, December 31, 2019 Raw materials $ 15.8 $ 14.1 Work in process 1.8 1.5 Finished goods 4.4 1.7 Total inventories $ 22.0 $ 17.3

Restricted Cash

Restricted Cash	6 Months Ended
	Jun. 30, 2020
Restricted Cash and Cash Equivalents [Abstract]
Restricted Cash	Restricted Cash The following table presents a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows. (in millions) June 30, December 31, Cash and cash equivalents $ 415.1 $ 112.3 Restricted cash 3.2 3.2 Total cash and cash equivalents and restricted cash $ 418.3 $ 115.5

Leases

Leases	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Leases	Leases At June 30, 2020, our operating leases consisted of the following: Address Type Square Feet Commencement Date Expiration Date 12780 El Camino Real (1) Office/Laboratory 141,000 August 7, 2019 July 31, 2031 12790 El Camino Real, Suite 130 (1) Office 2,000 December 1, 2019 July 31, 2031 12790 El Camino Real, Suite 150 (1) Office 8,000 August 7, 2019 July 31, 2031 12790 El Camino Real, Suite 300 (1) Office 28,000 December 1, 2019 July 31, 2031 12777 High Bluff Drive Office 45,000 July 1, 2018 July 31, 2029 12790 El Camino Real, Suite 200 (1) Office 28,000 February 1, 2021 July 31, 2031 12790 El Camino Real, Suite 100 (1) Office 17,000 February 1, 2021 July 31, 2031 ______________ (1) Under the terms of the 12780/12790 El Camino Real master lease, we have 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. As such, neither option was recognized as part of the associated operating lease right-of-use asset or liability. Note: In connection with our operating leases, in lieu of cash security deposits, Wells Fargo Bank, N.A., issued letters of credit on our behalf, which are secured by deposits totaling $3.2 million. Our operating lease cost was $5.0 million and $3.9 million for the six months ended June 30, 2020 and 2019, respectively. Cash paid for amounts in the measurement of lease liabilities for operating cash flows from operating leases was $4.3 million and $3.3 million for the six months ended June 30, 2020 and 2019, respectively. Our operating leases had a weighted average remaining lease term of approximately 11 years and 10 years at June 30, 2020 and December 31, 2019, respectively, and a weighted average discount rate of 5.8% at June 30, 2020 and December 31, 2019, respectively. Approximate future minimum lease payments under operating leases were as follows: (in millions) June 30, Year ending December 31, 2020 (6 months remaining) $ 4.3 Year ending December 31, 2021 10.6 Year ending December 31, 2022 10.9 Year ending December 31, 2023 11.2 Year ending December 31, 2024 11.6 Thereafter 79.7 Total operating lease payments 128.3 Less accreted interest 34.8 Total operating lease liabilities 93.5 Less current operating lease liabilities 9.2 Noncurrent operating lease liabilities $ 84.3 ______________ Note: Amounts presented in the table above exclude $28.3 million of non-cancelable future minimum lease payments for operating leases that have not yet commenced.

Convertible Senior Notes

Convertible Senior Notes	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Convertible Senior Notes	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 and entered into an indenture agreement, or the 2024 Indenture, with respect to the 2024 Notes. 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 (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 five (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 June 30, 2020, holders of the 2024 Notes may convert the 2024 Notes at any time during the period beginning on July 1, 2020 and ending at the close of business on September 30, 2020. Accordingly, the 2024 Notes have been classified as a current liability as of June 30, 2020. 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 for each of the 30 consecutive trading days during the observation period (as more fully described in the 2024 Indenture). 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 our 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 2024 Indenture. 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 volume weighted average price, or 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 that 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 our common stock, at our option. We may not redeem the 2024 Notes prior to May 15, 2021. On or after 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 our 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 its 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. We are required to separately account for the liability and equity components of the 2024 Notes as they may be settled entirely or partially in cash upon conversion in a manner that reflects our 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 was 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 June 30, 2020, the remaining period over which the discount on the liability component will be amortized was approximately 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 us. 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. The 2024 Notes, net of discounts and deferred financing costs, consisted of the following: (in millions) June 30, December 31, Principal $ 517.5 $ 517.5 Deferred financing costs (6.2) (6.9) Debt discount, net (91.8) (101.8) Net carrying amount $ 419.5 $ 408.8 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 $845.3 million at June 30, 2020 and $596.8 million at December 31, 2019.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) Per Share Net income (loss) per share was calculated as follows: Three Months Ended Six Months Ended (in millions, except per share data) 2020 2019 2020 2019 Net income (loss) - basic and diluted $ 79.6 $ 51.3 $ 117.0 $ (50.8) Weighted-average common shares outstanding: Basic 93.0 91.4 92.8 91.2 Effect of dilutive securities: Stock options 2.6 2.6 2.5 — Restricted stock 0.5 0.3 0.5 — 2024 Notes 2.1 0.5 1.8 — Diluted 98.2 94.8 97.6 91.2 Net income (loss) per share: Basic $ 0.86 $ 0.56 $ 1.26 $ (0.56) Diluted $ 0.81 $ 0.54 $ 1.20 $ (0.56) 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 are considered under the treasury stock method. Shares which have been excluded from diluted per share amounts because their effect would have been anti-dilutive were 2.2 million and 1.4 million for the three and six months ended June 30, 2020, respectively, and 2.3 million and 8.5 million for the three and six months ended June 30, 2019, respectively.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Takeda . In June 2020, we entered into an exclusive license agreement with Takeda to develop and commercialize certain compounds in Takeda’s early to mid-stage psychiatry pipeline. Specifically, Takeda granted us an exclusive license to the following seven assets: (i) NBI-1065844 (TAK-831) for schizophrenia, or the Phase II Asset, (ii) NBI-1065845 (TAK-653) for treatment-resistant depression, (iii) NBI-1065846 (TAK-041) for anhedonia (which together with the NBI-1065845 are referred to as the Phase II Ready Assets), and (iv) four non-clinical stage assets, or the Non-Clinical Assets. The agreement became effective in July 2020, upon expiration of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. The Phase II Asset is deemed a royalty-bearing product under the license agreement pursuant to which we will be responsible for all costs and expenses associated with the development, manufacture, and commercialization of such asset, subject to certain exceptions, and Takeda will be eligible to receive development and commercial milestones and royalties with respect to such asset, or a Royalty-Bearing Product, and Takeda will retain the right to opt-in to a profit sharing arrangement pursuant to which we and Takeda will equally share in the operating profits and losses related to such asset, subject to certain exceptions, in lieu of receiving milestones and royalties, or a Profit-Share Product. Subject to specified conditions, Takeda may elect to exercise such opt-in right for the Phase II Asset before we initiate a Phase III clinical trial for such Phase II Asset. Each of the Phase II Ready Assets is deemed a Profit-Share Product and Takeda will retain the right to opt-out of the profit-sharing arrangement for such asset pursuant to which such asset would become a Royalty-Bearing Product. Takeda may elect to exercise such opt-out rights with respect to a Phase II Ready Asset immediately following the completion of the second Phase II clinical trial for such Phase II Ready Asset. In addition, under certain circumstances related to the development and commercialization activities to be performed by us, Takeda may elect to opt-out of the profit-sharing arrangement for a Profit-Share Product before the initiation of a Phase III clinical trial for such product. Each of the Non-Clinical Assets will be Royalty-Bearing Products pursuant to which we will be responsible for all costs and expenses associated with the development, manufacture, and commercialization of such assets, subject to certain exceptions. In connection with the agreement, we paid Takeda $120.0 million upfront (less an earnest money deposit paid by us to Takeda in the first quarter of 2020) . Pursuant to the terms of the agreement, Takeda may also be entitled to receive payments of up to $1.9 billion upon the achievement of certain development and commercial milestones associated with Royalty-Bearing Products, as well as receive royalties on future net sales of Royalty-Bearing Products. On a country-by-country and product-by-product basis, royalty payments would commence on the first commercial sale of a Royalty-Bearing Product and terminate on the later of (i) the expiration of the last patent covering such Royalty-Bearing Product in such country, (ii) a number of years from the first commercial sale of such Royalty-Bearing Product in such country and (iii) the expiration of regulatory exclusivity for Royalty-Bearing Product in such country. Unless earlier terminated, the license agreement will continue on a licensed product-by-licensed product and country-by-country basis until the date on which, (i) for any Royalty-Bearing Product, the royalty term has expired in such country; and (ii) for any Profit-Share Product, for so long as we continue to develop, manufacture, or commercialize such licensed product. We may terminate the license agreement for convenience in its entirety or in one or more (but not all) of the United States, Japan, the European Union, and the United Kingdom, or the Major Markets, on 6 months’ written notice to Takeda (i) with respect to all licensed products prior to the first commercial sale of the first licensed product for which first commercial sale occurs, or (ii) with respect to all licensed products in one or more given target classes, as defined in the agreement, prior to the first commercial sale of the first licensed product in such target class(es) for which first commercial sale occurs. We may terminate the license agreement for convenience in its entirety or in one or more (but not all) of the Major Markets on 12 months’ written notice to Takeda (i) with respect to all licensed products following the first commercial sale of the first licensed product for which first commercial sale occurs, or (ii) with respect to all licensed products in one or more given target classes following the first commercial sale of the first licensed product in such target class(es) for which first commercial sale. Takeda may terminate the license agreement, subject to specified conditions, (i) if we challenge the validity or enforceability of certain Takeda intellectual property rights or (ii) on a target class-by-target class basis, in the event that we do not conduct any material development or commercialization activities with respect to any licensed product within such target class for a specified continuous period. Subject to a cure period, either party may terminate the license agreement in the event of any material breach, solely with respect to the target class of a licensed product to which such material breach relates, or in its entirety in the event of any material breach that relates to all licensed products.

Organization and Significant _2

Organization and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Description of Business	Description of Business . Neurocrine Biosciences, Inc., or Neurocrine Biosciences, 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 Biosciences. 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, or US, our first US Food and Drug Administration, or FDA, approved product. In April 2017, we received FDA approval of our first marketed product, INGREZZA, for the treatment of adults with tardive dyskinesia, or TD. Shortly after receiving FDA approval, we began commercializing INGREZZA in the US 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 receive royalties at tiered percentage rates on any net sales of ORILISSA. In April 2020, we received FDA approval for ONGENTYS ® (opicapone) as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients. FDA approval for ONGENTYS for Parkinson’s disease triggered a milestone payment of $20.0 million, which was expensed as research and development, or R&D, in the second quarter of 2020. In May 2020, AbbVie received approval from the FDA for ORIAHNN TM (elagolix) for the management of heavy menstrual bleeding associated with uterine fibroids in pre-menopausal women. FDA approval for ORIAHNN for uterine fibroids resulted in the achievement of a $30.0 million regulatory milestone, which was recognized as collaboration revenue in the second quarter of 2020. We are entitled to receive royalties at tiered percentage rates on any net sales of ORIAHNN. Our late-stage pipeline includes crinecerfont (NBI-74788) for the treatment of congenital adrenal hyperplasia, or CAH, in adult patients, 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 candidate for advanced Parkinson’s disease is partnered with Voyager Therapeutics, Inc., or Voyager. Our early-stage clinical pipeline includes crinecerfont for the treatment of CAH in pediatric patients, elagolix for the treatment of polycystic ovary syndrome, or PCOS, in women, NBI-921352 (XEN901), a clinical-stage candidate with potential in epilepsy, and NBI-827104 (ACT-709478), a T-type calcium channel blocker in clinical development for the treatment of a rare pediatric epilepsy. Our product candidate for PCOS is partnered with AbbVie. In May 2020, we entered into a collaboration and licensing agreement with Idorsia Pharmaceuticals Ltd, or Idorsia. In connection with the agreement, we paid Idorsia $45.0 million upfront to gain a license to NBI-827104 (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 agreement includes a research collaboration to discover and identify up to two additional novel T-type calcium channel blockers as development candidates. In June 2020, we entered into an exclusive license agreement with Takeda Pharmaceutical Company Limited, or Takeda, to develop and commercialize certain compounds in Takeda’s early to mid-stage psychiatry pipeline. The agreement became effective in July 2020, upon expiration of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. In connection with the agreement, we paid Takeda $120.0 million upfront (less an earnest money deposit paid by us to Takeda in the first quarter of 2020) to gain an exclusive license to seven of Takeda’s pipeline programs, including three clinical-stage assets for schizophrenia, treatment-resistant depression, and anhedonia. The collaboration also includes a cost-sharing arrangement for associated collaboration activities.
Basis of Presentation	Basis of Presentation . The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or GAAP, for interim financial information and with the instructions of the Securities and Exchange Commission, or SEC, on Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, the condensed consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of our financial position and of the results of operations and cash flows for the periods presented. The accompanying unaudited condensed consolidated financial statements include the accounts of Neurocrine Biosciences and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2019, included in our Annual Report on Form 10-K, or the 2019 Form 10-K, filed with the SEC. The results of operations for the interim period shown in this report are not necessarily indicative of the results that may be expected for any other interim period or the full year. The condensed consolidated balance sheet at December 31, 2019, has been derived from the audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. There were no significant changes to our significant accounting policies as disclosed in the 2019 Form 10-K, except as set forth below.
Debt Securities	Debt Securities. Debt securities consist of investments in certificates of deposit, corporate debt securities, and securities of government-sponsored entities. We classify debt securities as available-for-sale. Debt securities available-for-sale are recorded at fair value, with unrealized gains and losses included in other comprehensive income or loss, net of tax. We exclude accrued interest from both the fair value and amortized cost basis of debt securities. A debt security is placed on nonaccrual status at the time any principal or interest payments become 90 days delinquent. Interest accrued but not received for a debt security placed on nonaccrual status is reversed against interest income. Interest income includes amortization of purchase premium or discount. Premiums and discounts on debt securities are amortized using the effective interest rate method. Gains and losses on sales of debt securities are recorded on the trade date in investment income and other, net, and determined using the specific identification method.
Allowance for Credit Losses	Allowance for Credit Losses. For debt securities available-for-sale in an unrealized loss position, we first assess whether we intend to sell, or it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For debt securities available-for-sale that do not meet the aforementioned criteria, we evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the extent to which fair value is less than amortized cost, any changes in interest rates, and any changes to the rating of the security by a rating agency, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income or loss, as applicable. Accrued interest receivables on debt securities available-for-sale totaled $3.7 million at June 30, 2020. We do not measure an allowance for credit losses for accrued interest receivables. For the purposes of identifying and measuring an impairment, accrued interest is excluded from both the fair value and amortized cost basis of the debt security. Uncollectible accrued interest receivables associated with an impaired debt security are reversed against interest income upon identification of the impairment. No accrued interest receivables were written off during the six months ended June 30, 2020.
Fair Value of Financial Instruments	Fair Value of Financial Instruments. We record cash equivalents, debt securities available-for-sale and 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 fair value hierarchy consists of the following 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. Investments in debt securities available-for-sale are classified as Level 2 and carried at fair value. We estimate the fair value of debt securities available-for-sale by utilizing third-party pricing services. These pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. Such inputs include market pricing based on real-time trade data for similar instruments, issuer credit spreads, benchmark yields, broker/dealer quotes and other observable inputs. We validate valuations obtained from third-party pricing services by understanding the models used, obtaining market values from other pricing sources, and analyzing data in certain instances. Investments in equity securities of certain companies that are subject to holding period restrictions longer than one year are classified as Level 3 and carried at fair value using an option pricing valuation model. The most significant assumptions within the option pricing valuation model are the stock price volatility, which is based on the historical volatility of similar companies, and the discount for lack of marketability related to the term of the restrictions. The carrying amounts of accounts receivable and accounts payable and accrued liabilities approximate their fair values due to their short-term maturities.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements. ASU 2016-13. On January 1, 2020, we adopted Accounting Standards Update, or ASU, 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, using the modified retrospective transition method. For debt securities available-for-sale, the standard requires an investor to determine whether a decline in the fair value below the amortized cost basis of the investment is due to credit-related factors. Credit-related impairment is recognized as an allowance for credit loss on the balance sheet with a corresponding adjustment to earnings. Credit losses are limited to the amount by which the investment’s amortized cost basis exceeds its fair value and may be subsequently reversed if conditions change. Any impairment that is not credit related is recognized in other comprehensive income or loss, as applicable, net of applicable taxes. The adoption of ASU 2016-13 did not result in a cumulative-effect adjustment to retained earnings. The comparative prior period information continues to be reported under the accounting standards in effect during those periods. Recently Issued Accounting Pronouncements. ASU 2019-12. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and amends existing guidance to improve consistent application of Topic 740. ASU 2019-12 is effective for fiscal years beginning after December 15, 2021, and interim periods within those fiscal years, with early adoption permitted in any interim period for which financial statements have not yet been made available for issuance. We are currently evaluating the effect that ASU 2019-12 will have on our condensed consolidated financial statements and related disclosures.

Debt Securities (Tables)

Debt Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Gross Unrealized Gains and Losses, Allowance for Credit Losses and Fair Value of Debt Securities Available-For-Sale	The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive loss, allowance for credit losses, and fair value of debt securities available-for-sale at June 30, 2020, aggregated by major security type and contractual maturity: (in millions) Contractual Amortized Unrealized Unrealized Allowance for Credit Losses Fair Commercial paper Within 1 year $ 140.0 $ 0.1 $ — — $ 140.1 Corporate debt securities Within 1 year 287.8 2.0 — — 289.8 Securities of government-sponsored entities Within 1 year 102.5 0.8 — — 103.3 $ 530.3 $ 2.9 $ — $ — $ 533.2 Corporate debt securities 1 to 2 years $ 173.5 $ 1.7 $ — — $ 175.2 Securities of government-sponsored entities 1 to 2 years 20.0 — — — 20.0 $ 193.5 $ 1.7 $ — $ — $ 195.2 The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive income, and fair value of debt securities available-for-sale at December 31, 2019, aggregated by major security type and contractual maturity: (in millions) Contractual Amortized Unrealized Unrealized Fair Commercial paper Within 1 year $ 144.5 — — $ 144.5 Corporate debt securities Within 1 year 270.5 0.5 — 271.0 Securities of government-sponsored entities Within 1 year 142.3 0.4 — 142.7 $ 557.3 $ 0.9 $ — $ 558.2 Corporate debt securities 1 to 2 years $ 250.5 $ 0.5 $ (0.1) $ 250.9 Securities of government-sponsored entities 1 to 2 years 48.8 — — 48.8 $ 299.3 $ 0.5 $ (0.1) $ 299.7
Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position	The following table summarizes debt securities available-for-sale in an unrealized loss position at December 31, 2019, aggregated by major security type and length of time in a continuous unrealized loss position: Less Than 12 Months 12 Months or Longer Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Corporate debt securities $ 186.1 $ (0.1) $ — $ — $ 186.1 $ (0.1)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Investments Measured at Fair Value on Recurring Basis	Investments at June 30, 2020, which were measured at fair value on a recurring basis, consisted of the following: Fair Value Measurements Using (in millions) Fair Value Level 1 Level 2 Level 3 Cash and cash equivalents: Cash and money market funds $ 415.1 $ 415.1 $ — $ — Total cash and cash equivalents 415.1 415.1 — — Restricted cash: Certificates of deposit 3.2 3.2 — — Total restricted cash 3.2 3.2 — — Debt securities available-for-sale: Commercial paper 140.1 — 140.1 — Corporate debt securities 465.0 — 465.0 — Securities of government-sponsored entities 123.3 — 123.3 — Total debt securities available-for-sale 728.4 — 728.4 — Equity securities: Equity securities–biotechnology industry 50.7 — — 50.7 Total equity securities 50.7 — — 50.7 Total recurring fair value measurements $ 1,197.4 $ 418.3 $ 728.4 $ 50.7 Investments at December 31, 2019, which were measured at fair value on a recurring basis, consisted of the following: Fair Value Measurements Using (in millions) Fair Value Level 1 Level 2 Level 3 Cash and cash equivalents: Cash and money market funds $ 112.3 $ 112.3 — — Total cash and cash equivalents 112.3 112.3 — — Restricted cash: Certificates of deposit 3.2 3.2 — — Total restricted cash 3.2 3.2 — — Debt securities available-for-sale: Commercial paper 144.5 — 144.5 — Corporate debt securities 521.9 — 521.9 — Securities of government-sponsored entities 191.5 — 191.5 — Total debt securities available-for-sale 857.9 — 857.9 — Equity securities: Equity securities–biotechnology industry 55.9 — — 55.9 Total equity securities 55.9 — — 55.9 Total recurring fair value measurements $ 1,029.3 $ 115.5 $ 857.9 $ 55.9
Reconciliation of Our Investment in Restricted Equity Securities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following table presents a reconciliation of equity security investments, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Three Months Ended Six Months Ended (in millions) 2020 2019 2020 2019 Balance at beginning of period $ 39.4 $ 56.4 $ 55.9 $ — Purchases — — — 54.7 Unrealized gains (losses) included in earnings 11.3 21.0 (5.2) 22.7 Balance at end of period $ 50.7 $ 77.4 $ 50.7 $ 77.4

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consisted of the following: (in millions) June 30, December 31, 2019 Raw materials $ 15.8 $ 14.1 Work in process 1.8 1.5 Finished goods 4.4 1.7 Total inventories $ 22.0 $ 17.3

Restricted Cash (Tables)

Restricted Cash (Tables)	6 Months Ended
	Jun. 30, 2020
Restricted Cash and Cash Equivalents [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents, and Restricted Cash	The following table presents a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows. (in millions) June 30, December 31, Cash and cash equivalents $ 415.1 $ 112.3 Restricted cash 3.2 3.2 Total cash and cash equivalents and restricted cash $ 418.3 $ 115.5

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Schedule of Description of Operating Lease	At June 30, 2020, our operating leases consisted of the following: Address Type Square Feet Commencement Date Expiration Date 12780 El Camino Real (1) Office/Laboratory 141,000 August 7, 2019 July 31, 2031 12790 El Camino Real, Suite 130 (1) Office 2,000 December 1, 2019 July 31, 2031 12790 El Camino Real, Suite 150 (1) Office 8,000 August 7, 2019 July 31, 2031 12790 El Camino Real, Suite 300 (1) Office 28,000 December 1, 2019 July 31, 2031 12777 High Bluff Drive Office 45,000 July 1, 2018 July 31, 2029 12790 El Camino Real, Suite 200 (1) Office 28,000 February 1, 2021 July 31, 2031 12790 El Camino Real, Suite 100 (1) Office 17,000 February 1, 2021 July 31, 2031 ______________ (1) Under the terms of the 12780/12790 El Camino Real master lease, we have 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. As such, neither option was recognized as part of the associated operating lease right-of-use asset or liability.
Lessee, Operating Lease, Liability, Maturity	Approximate future minimum lease payments under operating leases were as follows: (in millions) June 30, Year ending December 31, 2020 (6 months remaining) $ 4.3 Year ending December 31, 2021 10.6 Year ending December 31, 2022 10.9 Year ending December 31, 2023 11.2 Year ending December 31, 2024 11.6 Thereafter 79.7 Total operating lease payments 128.3 Less accreted interest 34.8 Total operating lease liabilities 93.5 Less current operating lease liabilities 9.2 Noncurrent operating lease liabilities $ 84.3 ______________ Note: Amounts presented in the table above exclude $28.3 million of non-cancelable future minimum lease payments for operating leases that have not yet commenced.

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Summary of Notes Net of Discount and Deferred Financing Costs	The 2024 Notes, net of discounts and deferred financing costs, consisted of the following: (in millions) June 30, December 31, Principal $ 517.5 $ 517.5 Deferred financing costs (6.2) (6.9) Debt discount, net (91.8) (101.8) Net carrying amount $ 419.5 $ 408.8

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Schedule of Net Income Per Share	Net income (loss) per share was calculated as follows: Three Months Ended Six Months Ended (in millions, except per share data) 2020 2019 2020 2019 Net income (loss) - basic and diluted $ 79.6 $ 51.3 $ 117.0 $ (50.8) Weighted-average common shares outstanding: Basic 93.0 91.4 92.8 91.2 Effect of dilutive securities: Stock options 2.6 2.6 2.5 — Restricted stock 0.5 0.3 0.5 — 2024 Notes 2.1 0.5 1.8 — Diluted 98.2 94.8 97.6 91.2 Net income (loss) per share: Basic $ 0.86 $ 0.56 $ 1.26 $ (0.56) Diluted $ 0.81 $ 0.54 $ 1.20 $ (0.56)

Organization and Significant _3

Organization and Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	3 Months Ended		6 Months Ended		120 Months Ended
	Jun. 30, 2010USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)subsidiary	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)	Jul. 31, 2020USD ($)	May 31, 2020USD ($)	Apr. 30, 2020USD ($)
Product Information [Line Items]
Number of wholly owned Irish subsidiaries | subsidiary				2
Revenue from contract with customer		$ 302,400,000	$ 183,500,000	$ 539,500,000	$ 321,900,000
Accrued interest receivables write-off threshold period		90 days		90 days		90 days
Accrued interest receivables		$ 3,700,000		$ 3,700,000		$ 3,700,000
Accrued interest receivables write-off				$ 0
B I A L | Collaborative Arrangement
Product Information [Line Items]
Milestone payment									$ 20,000,000
AbbVie | Collaborative Arrangement
Product Information [Line Items]
Revenue from contract with customer	$ 75,000,000	$ 30,000,000				$ 165,000,000
Idorsia | Collaborative Arrangement
Product Information [Line Items]
Upfront payments made								$ 45,000,000
Takeda | Collaborative Arrangement | Subsequent Event
Product Information [Line Items]
Upfront payments made							$ 120,000,000

Significant Collaboration and_2

Significant Collaboration and Licensing Agreements - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended					3 Months Ended			6 Months Ended		9 Months Ended	27 Months Ended	28 Months Ended	120 Months Ended
	May 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2015	Jun. 30, 2010	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2017	Jun. 30, 2020	Apr. 30, 2020	Mar. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from contract with customer						$ 302,400,000		$ 183,500,000	$ 539,500,000	$ 321,900,000
Equity securities fair value		$ 55,900,000				50,700,000	$ 55,900,000		50,700,000		$ 50,700,000			$ 50,700,000
Acquired in-process research and development						46,000,000		5,000,000	46,000,000	$ 118,100,000
AbbVie | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from contract with customer					$ 75,000,000	30,000,000								165,000,000
Potential milestone payment receipts						366,000,000			366,000,000		366,000,000			366,000,000
Collaboration termination notice period					180 days
AbbVie | Collaborative Arrangement | Patents [Member] | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Patent term					10 years
B I A L | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payment															$ 20,000,000
Potential milestone payments						75,000,000			75,000,000		75,000,000			75,000,000
Voyager | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration termination notice period			180 days
Potential milestone payments																$ 1,700,000,000
Upfront payments made																115,000,000
Equity securities cost																$ 50,000,000
Share price (in USD per share)																$ 11.9625
Equity securities fair value																$ 54,700,000
Acquired in-process research and development			$ 5,000,000					$ 113,100,000
Voyager | Collaborative Arrangement | Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares owned																4.2
Xenon | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration termination notice period		90 days
Potential milestone payments						1,700,000,000			1,700,000,000		1,700,000,000			1,700,000,000
Upfront payments made		$ 30,000,000					30,000,000
Equity securities cost		$ 20,000,000					$ 20,000,000
Share price (in USD per share)		$ 14.196					$ 14.196
Equity securities fair value		$ 14,100,000					$ 14,100,000
Acquired in-process research and development							$ 36,200,000
Xenon | Collaborative Arrangement | Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares owned		1.4					1.4
Mitsubishi Tanabe | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from contract with customer												$ 15,000,000	$ 19,800,000
Potential milestone payment receipts						70,000,000			70,000,000		70,000,000			70,000,000
Collaboration termination notice period				180 days
Upfront payments received				$ 30,000,000
Deferred revenue recognized									1,300,000		2,100,000
Deferred revenue, balance						8,100,000			8,100,000		8,100,000			8,100,000
Mitsubishi Tanabe | Collaborative Arrangement | Patents [Member] | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Patent term				10 years
Idorsia | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration termination notice period	90 days
Potential commercial milestone payments						750,000,000			750,000,000		750,000,000			750,000,000
Upfront payments made	$ 45,000,000
Acquired in-process research and development						45,000,000
Incremental funding provided	$ 7,200,000
Research collaboration term	2 years
Idorsia | Collaborative Arrangement | NBI-827104
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments						365,000,000			365,000,000		365,000,000			365,000,000
Idorsia | Collaborative Arrangement | Development Product Candidates
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments						$ 620,000,000			$ 620,000,000		$ 620,000,000			$ 620,000,000

Debt Securities - Amortized Cos

Debt Securities - Amortized Cost, Gross Unrealized Gains and Losses, Allowance for Credit Losses and Fair Value of Debt Securities Available-For-Sale (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 530.3	$ 557.3
Unrealized Gain	2.9	0.9
Unrealized Loss	0	0
Allowance for Credit Losses	0
Fair Value	533.2	558.2
Short-term investments | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	140	144.5
Unrealized Gain	0.1	0
Unrealized Loss	0	0
Allowance for Credit Losses	0
Fair Value	140.1	144.5
Short-term investments | Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	287.8	270.5
Unrealized Gain	2	0.5
Unrealized Loss	0	0
Allowance for Credit Losses	0
Fair Value	289.8	271
Short-term investments | Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	102.5	142.3
Unrealized Gain	0.8	0.4
Unrealized Loss	0	0
Allowance for Credit Losses	0
Fair Value	103.3	142.7
Long-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	193.5	299.3
Unrealized Gain	1.7	0.5
Unrealized Loss	0	(0.1)
Allowance for Credit Losses	0
Fair Value	195.2	299.7
Long-term investments | Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	173.5	250.5
Unrealized Gain	1.7	0.5
Unrealized Loss	0	(0.1)
Allowance for Credit Losses	0
Fair Value	175.2	250.9
Long-term investments | Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20	48.8
Unrealized Gain	0	0
Unrealized Loss	0	0
Allowance for Credit Losses	0
Fair Value	$ 20	$ 48.8

Debt Securities - Additional In

Debt Securities - Additional Information (Detail)	Jun. 30, 2020security
Investments, Debt and Equity Securities [Abstract]
Number of debt securities available for sale	158
Number of debt securities available for sale in unrealized loss position	17

Debt Securities - Gross Unreali

Debt Securities - Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position (Detail) - Corporate debt securities $ in Millions	Dec. 31, 2019USD ($)
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 186.1
Less Than 12 Months, Unrealized Loss	(0.1)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Loss	0
Total Fair Value	186.1
Total Unrealized Loss	$ (0.1)

Fair Value Measurements - Inves

Fair Value Measurements - Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 1,197.4	$ 1,029.3
Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	418.3	115.5
Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	728.4	857.9
Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	50.7	55.9
Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	415.1	112.3
Cash and money market funds | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	415.1	112.3
Cash and money market funds | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Cash and money market funds | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	415.1	112.3
Total cash and cash equivalents | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	415.1	112.3
Total cash and cash equivalents | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total cash and cash equivalents | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3.2	3.2
Certificates of deposit | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3.2	3.2
Certificates of deposit | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Certificates of deposit | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3.2	3.2
Total restricted cash | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3.2	3.2
Total restricted cash | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total restricted cash | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	140.1	144.5
Commercial paper | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Commercial paper | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	140.1	144.5
Commercial paper | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	465	521.9
Corporate debt securities | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Corporate debt securities | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	465	521.9
Corporate debt securities | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Securities of government-sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	123.3	191.5
Securities of government-sponsored entities | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Securities of government-sponsored entities | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	123.3	191.5
Securities of government-sponsored entities | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total debt securities available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	728.4	857.9
Total debt securities available-for-sale | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total debt securities available-for-sale | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	728.4	857.9
Total debt securities available-for-sale | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Equity securities–biotechnology industry
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	50.7	55.9
Equity securities–biotechnology industry | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Equity securities–biotechnology industry | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Equity securities–biotechnology industry | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	50.7	55.9
Total equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	50.7	55.9
Total equity securities | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total equity securities | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0	0
Total equity securities | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	$ 50.7	$ 55.9

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Our Investment in Restricted Equity Securities Measured at Fair Value on Quarterly Basis Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning of period			$ 55.9
Purchases			0	$ 54.7
Unrealized gains (losses) included in earnings	$ 11.3	$ 21	(5.2)	22.7
Balance at end of period	50.7		50.7
Equity Securities | Level 3 | Long-term investments | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning of period	39.4	56.4	55.9	0
Purchases	0	0	0	54.7
Unrealized gains (losses) included in earnings	11.3	21	(5.2)	22.7
Balance at end of period	$ 50.7	$ 77.4	$ 50.7	$ 77.4

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Discount for Lack of Marketability	Jun. 30, 2020
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities measurement input	0.175
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities measurement input	0.315
Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities measurement input	0.275

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 15.8	$ 14.1
Work in process	1.8	1.5
Finished goods	4.4	1.7
Total inventories	$ 22	$ 17.3

Restricted Cash - Summary of Re

Restricted Cash - Summary of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 415.1	$ 112.3
Restricted cash	3.2	3.2
Total cash and cash equivalents and restricted cash	$ 418.3	$ 115.5

Leases - Disclosure (Detail)

Leases - Disclosure (Detail) $ in Millions	Jun. 30, 2020USD ($)ft²renewalOption	Dec. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Restricted cash | $	$ 3.2	$ 3.2
Letter of Credit
Lessee, Lease, Description [Line Items]
Restricted cash | $	$ 3.2
12780/12790 El Camino Real Master Lease [Member]
Lessee, Lease, Description [Line Items]
Number of renewal options | renewalOption	2
Renewal term	10 years
12780 El Camino Real
Lessee, Lease, Description [Line Items]
Square feet	141,000
12790 El Camino Real, Suite 130
Lessee, Lease, Description [Line Items]
Square feet	2,000
12790 El Camino Real, Suite 150
Lessee, Lease, Description [Line Items]
Square feet	8,000
12790 El Camino Real, Suite 300
Lessee, Lease, Description [Line Items]
Square feet	28,000
12777 High Bluff Drive
Lessee, Lease, Description [Line Items]
Square feet	45,000
12790 El Camino Real, Suite 200
Lessee, Lease, Description [Line Items]
Square feet	28,000
12790 El Camino Real, Suite 100
Lessee, Lease, Description [Line Items]
Square feet	17,000

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Leases [Abstract]
Cost	$ 5	$ 3.9
Payments	$ 4.3	$ 3.3
Weighted average remaining lease term	11 years		10 years
Weighted average discount rate	5.80%		5.80%

Leases - Liability, Payment, Du

Leases - Liability, Payment, Due (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Year ending December 31, 2020 (6 months remaining)	$ 4.3
Year ending December 31, 2021	10.6
Year ending December 31, 2022	10.9
Year ending December 31, 2023	11.2
Year ending December 31, 2024	11.6
Thereafter	79.7
Total operating lease payments	128.3
Less accreted interest	34.8
Total operating lease liabilities	93.5
Less current operating lease liabilities	9.2
Noncurrent operating lease liabilities	84.3	$ 86.7
Non-cancelable future minimum lease payments for operating leases that have not yet commenced	$ 28.3

Convertible Senior Notes - Addi

Convertible Senior Notes - Additional Information (Detail) $ / shares in Units, shares in Millions	May 02, 2017USD ($)d$ / sharesshares	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Principal amount		$ 517,500,000	$ 517,500,000
2.25% Convertible Senior Notes due 2024
Debt Instrument [Line Items]
Principal amount	$ 517,500,000
Interest rate percentage	2.25%
Proceeds from issuance	$ 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%
Number of consecutive business days	5 days
Principal amount on conversion rate	$ 1,000
Minimum percentage of common stock price trigger	98.00%
Conversion observation period	25 days
Convertible senior notes convertible in to shares	0.0131711
Convertible senior notes conversion price (in USD per share) | $ / shares	$ 75.92
Shares issued to settle notes at initial conversion rate (in shares) | shares	6.8
Convertible senior note premium	42.50%
Market price of common stock (in USD per share) | $ / shares	$ 53.28
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
Transaction cost related to issuance of convertible senior notes	$ 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		$ 845,300,000	$ 596,800,000

Convertible Senior Notes - Debt

Convertible Senior Notes - Debt Net of Discounts and Deferred Financing Costs (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Principal	$ 517.5	$ 517.5
Deferred financing costs	(6.2)	(6.9)
Debt discount, net	(91.8)	(101.8)
Net carrying amount	$ 419.5	$ 408.8

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Schedule of Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Subsidiary, Sale of Stock [Line Items]
Net income (loss) - basic and diluted	$ 79.6	$ 51.3	$ 117	$ (50.8)
Weighted-average common shares outstanding:
Basic (in shares)	93	91.4	92.8	91.2
Effect of dilutive securities:
Diluted (in shares)	98.2	94.8	97.6	91.2
Net income per share:
Basic (in USD per share)	$ 0.86	$ 0.56	$ 1.26	$ (0.56)
Diluted (in USD per share)	$ 0.81	$ 0.54	$ 1.20	$ (0.56)
2024 Notes
Effect of dilutive securities:
2024 Notes (in shares)	2.1	0.5	1.8	0
Stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)	2.6	2.6	2.5	0
Restricted stock
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0.5	0.3	0.5	0

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock Options Restricted Stock Units And Convertible Senior Notes
Short-term Debt [Line Items]
Antidilutive shares (in shares)	2.2	2.3	1.4	8.5
2.25% Convertible Senior Notes due 2024
Short-term Debt [Line Items]
Antidilutive shares (in shares)			6.8

Subsequent Events (Details)

Subsequent Events (Details) - Takeda - Collaborative Arrangement - Subsequent Event $ in Millions	Jul. 31, 2020USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payments made	$ 120
Potential milestone payments	$ 1,900

Uncategorized Items - nbix-2020

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201602Member