0000914475-21-000020 | 10-K | XBRL Viewer | Neurocrine Biosciences INC

Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2020	Jan. 29, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 11,231,617,436
Entity Common Stock, Shares Outstanding		93,943,645
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement relating to the registrant’s annual meeting of stockholders to be filed pursuant to Regulation 14A within 120 days following the end of the registrant’s fiscal year ended December 31, 2020 are incorporated by reference into Part III of this Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000914475

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 187.1	$ 112.3
Debt securities available-for-sale (amortized cost $612.4 million at December 31, 2020 and $557.3 million at December 31, 2019)	613.9	558.2
Accounts receivable	157.1	126.6
Inventories	28.0	17.3
Other current assets	30.1	16.6
Total current assets	1,016.2	831.0
Debt securities available-for-sale (amortized cost $226.7 million at December 31, 2020 and $299.3 million at December 31, 2019)	227.1	299.7
Right-of-use assets	82.8	74.3
Equity securities	38.2	55.9
Property and equipment, net	44.6	41.9
Deferred tax assets	319.4	0.0
Restricted cash	3.2	3.2
Other long-term assets	3.2	0.0
Total assets	1,734.7	1,306.0
Current liabilities:
Accounts payable and accrued liabilities	168.7	141.3
Convertible senior notes	0.0	408.8
Other current liabilities	17.8	15.2
Total current liabilities	186.5	565.3
Convertible senior notes	317.9	0.0
Noncurrent operating lease liabilities	94.4	86.7
Other long-term liabilities	9.7	17.1
Total liabilities	608.5	669.1
Stockholders’ equity:
Preferred stock, $0.001 par value; 5.0 shares authorized; no shares issued and outstanding at December 31, 2020 and 2019	0.0	0.0
Common stock, $0.001 par value; 220.0 shares authorized; issued and outstanding shares were 93.5 million and 92.3 million at December 31, 2020 and 2019, respectively	0.1	0.1
Additional paid-in capital	1,849.7	1,768.1
Accumulated other comprehensive income	1.8	1.4
Accumulated deficit	(725.4)	(1,132.7)
Total stockholders’ equity	1,126.2	636.9
Total liabilities and stockholders’ equity	$ 1,734.7	$ 1,306.0

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000.0	5,000,000.0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares outstanding (in shares)	93,500,000	92,300,000
Common stock, shares issued (in shares)	93,500,000	92,300,000
Common stock, shares authorized (in shares)	220,000,000.0	220,000,000.0
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Short-term investments
Amortized cost	$ 612.4	$ 557.3
Long-term investments
Amortized cost	$ 226.7	$ 299.3

Consolidated Statements Income and Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Revenues	$ 1,045.9	$ 788.1	$ 451.2
Operating expenses:
Cost of sales	10.1	7.4	4.9
Research and development	275.0	200.0	155.8
Acquired in-process research and development	164.5	154.3	4.8
Selling, general and administrative	433.3	354.1	248.9
Total operating expenses	882.9	715.8	414.4
Operating income	163.0	72.3	36.8
Other (expense) income:
Interest expense	(32.8)	(32.0)	(30.5)
Unrealized loss on restricted equity securities	(17.7)	(13.0)	0.0
Loss on extinguishment of convertible senior notes	(18.4)	0.0	0.0
Investment income and other, net	12.6	19.2	15.5
Total other expense, net	(56.3)	(25.8)	(15.0)
Income before (benefit from) provision for income taxes	106.7	46.5	21.8
(Benefit from) provision for income taxes	(300.6)	9.5	0.7
Net income	407.3	37.0	21.1
Unrealized gain (loss) on debt securities available-for-sale	0.4	3.4	(0.1)
Comprehensive income	$ 407.7	$ 40.4	$ 21.0
Net income (loss) per share, basic (in USD per share)	$ 4.38	$ 0.40	$ 0.23
Net income (loss) per share, diluted (in USD per share)	$ 4.16	$ 0.39	$ 0.22
Weighted average common shares outstanding, basic (in shares)	93.1	91.6	90.2
Weighted average common shares outstanding, diluted (in shares)	97.8	95.7	95.4
Product sales, net
Revenues:
Revenues	$ 994.1	$ 752.9	$ 409.6
Collaboration revenue
Revenues:
Revenues	$ 51.8	$ 35.2	$ 41.6

Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative-effect adjustment to equity due to adoption of ASU 2016-02	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative-effect adjustment to equity due to adoption of ASU 2016-02
Beginning balance (in shares) at Dec. 31, 2017			88,800,000
Beginning balance at Dec. 31, 2017	$ 372.2		$ 0.1	$ 1,572.8	$ (1.9)	$ (1,198.8)
Net income	21.1					21.1
Unrealized gain (loss) on debt securities available-for sale	(0.1)				(0.1)
Share-based compensation expense	$ 58.1			58.1
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Issuance of common stock for vested restricted stock units (in shares)			400,000
Issuance of common stock for stock option exercises (in shares)			1,600,000
Issuance of common stock for stock option exercises	$ 29.5			29.5
Ending balance (in shares) at Dec. 31, 2018			90,800,000
Ending balance at Dec. 31, 2018	480.8	$ 8.0	$ 0.1	1,660.4	(2.0)	(1,177.7)	$ 8.0
Net income	37.0					37.0
Unrealized gain (loss) on debt securities available-for sale	3.4				3.4
Share-based compensation expense	75.3			75.3
Issuance of common stock for vested restricted stock units (in shares)			400,000
Issuance of common stock for stock option exercises (in shares)			1,000,000.0
Issuance of common stock for stock option exercises	27.3			27.3
Issuance of common stock for employee stock purchase plan (in shares)			100,000
Issuance of common stock for employee stockpurchase plan	5.1			5.1
Ending balance (in shares) at Dec. 31, 2019			92,300,000
Ending balance at Dec. 31, 2019	636.9		$ 0.1	1,768.1	1.4	(1,132.7)
Net income	407.3					407.3
Unrealized gain (loss) on debt securities available-for sale	0.4				0.4
Share-based compensation expense	100.0			100.0
Equity component of repurchased convertible senior notes, net	$ (47.5)			(47.5)
Issuance of common stock for vested restricted stock units (in shares)			500,000
Issuance of common stock for stock option exercises (in shares)	600,000		600,000
Issuance of common stock for stock option exercises	$ 23.5			23.5
Issuance of common stock for employee stock purchase plan (in shares)			100,000
Issuance of common stock for employee stockpurchase plan	5.6			5.6
Ending balance (in shares) at Dec. 31, 2020			93,500,000
Ending balance at Dec. 31, 2020	$ 1,126.2		$ 0.1	$ 1,849.7	$ 1.8	$ (725.4)

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net income	$ 407.3	$ 37.0	$ 21.1
Reconciliation of net income to net cash provided by operating activities:
Share-based compensation expense	100.0	75.3	58.1
Depreciation	8.6	7.4	4.0
Amortization of debt discount	20.0	18.9	17.6
Amortization of debt issuance costs	1.4	1.4	1.3
Change in fair value of equity securities	17.7	13.0	0.0
Deferred income taxes (including benefit from valuation allowance release)	(310.7)	0.0	0.0
Loss on extinguishment of convertible senior notes	18.4	0.0	0.0
Other	3.7	(1.2)	1.0
Changes in operating assets and liabilities:
Accounts receivable	(30.5)	(69.2)	(25.1)
Inventories	(10.7)	(6.4)	(3.5)
Accounts payable and accrued liabilities	26.9	54.0	24.2
Other assets and liabilities, net	(23.6)	16.8	2.7
Net cash provided by operating activities	228.5	147.0	101.4
Cash Flows from Investing Activities:
Purchases of debt securities available-for-sale	(735.5)	(797.2)	(545.9)
Sales and maturities of debt securities available-for-sale	750.5	669.7	327.8
Purchases of equity securities	0.0	(68.9)	0.0
Purchases of property and equipment	(10.9)	(14.7)	(24.8)
Net cash provided by (used in) investing activities	4.1	(211.1)	(242.9)
Cash Flows from Financing Activities:
Issuances of common stock under benefit plans	29.1	32.4	29.5
Partial repurchase of convertible senior notes	(186.9)	0.0	0.0
Net cash (used in) provided by financing activities	(157.8)	32.4	29.5
Change in cash and cash equivalents and restricted cash	74.8	(31.7)	(112.0)
Cash and cash equivalents and restricted cash at beginning of period	115.5	147.2	259.2
Cash and cash equivalents and restricted cash at end of period	190.3	115.5	147.2
Supplemental Disclosure:
Non-cash capital expenditures	1.4	1.0	2.3
Right-of-use assets acquired through operating leases	12.8	77.1	0.0
Cash paid for interest	11.6	11.6	11.6
Cash paid for income taxes	$ 15.3	$ 0.5	$ 0.0

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Business Activities. Neurocrine Biosciences, Inc., or Neurocrine, the Company, we, our or us, was incorporated in California in 1992 and reincorporated in Delaware in 1996. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of Neurocrine. We also have two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. both of which were formed in December 2014 and are inactive. We are a neuroscience-focused biopharmaceutical company dedicated to discovering, developing and delivering life-changing treatments for patients with serious, challenging and under-addressed neurological, endocrine and psychiatric disorders. Our diverse portfolio includes FDA-approved treatments for tardive dyskinesia, Parkinson’s disease, endometriosis, uterine fibroids and clinical programs in multiple therapeutic areas. For nearly three decades, we specialize in targeting and interrupting disease-causing mechanisms involving the interconnected pathways of the nervous and endocrine systems. (*in collaboration with AbbVie Inc.) Principles of Consolidation. The consolidated financial statements include the accounts of Neurocrine as well as our wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates. Industry Segment and Geographic Information. We operate in a single industry segment – the discovery, development and marketing of pharmaceuticals for the treatment of neurological, endocrine and psychiatric-based diseases and disorders. We had no foreign-based operations during any of the years presented. Reclassifications. Certain amounts in prior year periods have been reclassified to conform with the presentation adopted in the current year. Cash Equivalents. We consider all highly liquid investments that are readily convertible into cash and have an original maturity of three months or less at the time of purchase to be cash equivalents. Accounts Receivable. Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks and any allowance for doubtful accounts. We estimate the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of our customers and individual customer circumstances. To date, an allowance for doubtful accounts has not been material. 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 December 31, 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 2020, 2019 or 2018. 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. There were no transfers between levels in the fair value hierarchy during 2020 or 2019. Inventory. Inventory is valued at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on the first-in, first-out method. We assess the valuation of our inventory on a quarterly basis and adjust the value for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand. Inventory costs resulting from these adjustments are recognized as cost of sales in the period in which they are incurred. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, we capitalize pre-launch inventory costs prior to regulatory approval. Property and Equipment. Property and equipment are stated at cost and depreciated over the estimated useful lives of the assets using the straight-line method. Equipment is depreciated over an average estimated useful life of three to seven years. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the remaining lease term. Depreciation expense was $8.6 million for 2020, $7.4 million for 2019 and $4.0 million for 2018. Impairment of Long-Lived Assets. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If the carrying amount is not recoverable, we measure the amount of any impairment by comparing the carrying value of the asset to the present value of the expected future cash flows associated with the use of the asset. Revenue Recognition. We recognize revenue when the customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. Revenue is recognized using a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. Product Sales, Net. In the U.S., our product sales, net consist of sales of INGREZZA, primarily to specialty pharmacy providers and a specialty distributor, and sales of ONGENTYS, primarily to wholesale distributors. We recognize product sales, net when the customer obtains control of our product, which occurs at a point in time, typically upon delivery of our product to the customer. Revenues from product sales are recorded net of reserves established for applicable discounts and allowances that are offered within contracts with our customers, payors and other third parties. Such estimates are based on information received from external sources (such as written or oral information obtained from our customers with respect to their period-end inventory levels and sales to end-users during the reporting period), as supplemented by management’s judgement. Our process for estimating reserves established for these variable consideration components does not differ materially from historical practices. The transaction price, which includes variable consideration reflecting the impact of discounts and allowances, may be subject to constraint and is included in the net sales price only to the extent that it is probable that a significant reversal of the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment. Our significant categories of sales discounts and allowances are as follows: Product Discounts. Product discounts are based on payment terms extended to our customers at the time of sale, which include incentives offered for prompt payment. We maintain a reserve for product discounts based on our historical experience, including the timing of customer payments. To date, actual product discounts have not differed materially from our estimates. Government Rebates. We are obligated to pay rebates for mandated discounts under the Medicaid Drug Rebate Program. The liability for such rebates consists of invoices received for claims from prior quarters that remain unpaid, or for which an invoice has not been received, and estimated rebates for the current applicable reporting period. Such estimates are based on actual historical rebates by state, estimated payor mix, state and federal regulations and relevant contractual terms, as supplemented by management’s judgement. Our rebate accrual calculations require us to project the magnitude of our sales, by state, that will be subject to these rebates. There is a significant time-lag in our receiving rebate notices from each state (generally, several months or longer after a sale is recognized). Estimated rebates are recorded as a reduction of revenue in the period the related sale is recognized. To date, actual government rebates have not differed materially from our estimates. Chargebacks. The difference between the list price, or the price at which we sell our products to our customers, and the contracted price, or the price at which our customers sell our products to qualified healthcare professionals, is charged back to us by our customers. In addition to actual chargebacks received, we maintain a reserve for chargebacks based on estimated contractual discounts on product inventory levels on-hand in our distribution channel. To date, actual chargebacks have not differed materially from our estimates. Payor and Pharmacy Rebates. We are obligated to pay rebates as a percentage of sales under payor and pharmacy contracts. We estimate these rebates based on actual historical rebates, contractual rebate percentages, sales made through the payor channel and purchases made by pharmacies. To date, actual payor and pharmacy rebates have not differed materially from our estimates. Co-payment Assistance. We offer financial assistance to qualified patients with prescription drug co-payments required by insurance. We accrue for copay assistance based on estimated claims and the cost per claim we expect to receive associated with inventory that remains in the distribution channel at period end. To date, actual copay assistance has not differed materially from our estimates. Distributor and Other Fees. In connection with the sales of our products, we pay distributor and other fees to certain customers that provide us with inventory management, data and distribution services, which are generally recorded as a reduction of revenue. To the extent we can demonstrate a separable benefit and fair value for these services, we classify the associated costs in selling, general and administrative expenses. These costs are typically known at the time of sale, resulting in minimal adjustments subsequent to the period of sale. Product Returns. For INGREZZA, we offer our customers product return rights primarily limited to errors in shipment and damaged product. We do not permit returns of INGREZZA for expiring or expired product. Accordingly, we have limited return risk resulting from INGREZZA product sales and therefore do not record an associated returns allowance. For ONGENTYS, we offer our customers product return rights primarily limited to errors in shipment, damaged product, and expiring or expired product, provided it is within a specified period around the product expiration date, as set forth in the associated distribution agreement. Once product is returned, it is destroyed. Where actual returns history is not available, we estimate the associated returns allowance based on benchmarking data for similar products and industry experience. We record this estimate as a reduction of revenue in the period the related sale is recognized. To date, actual product returns have not differed materially from our estimates. Collaboration Revenues. We have entered into collaboration and licensing agreements under which we license certain rights to our product candidates to third parties. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; development, regulatory, and/or commercial milestone payments; and royalties on net sales of licensed products. Licenses of Intellectual Property. If the license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we use judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments. At the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, we evaluate whether achieving the milestones is considered probable and estimate the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone is included in the transaction price. Milestone payments that are not within our control, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer. Royalty Revenues. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Each quarterly period, sales-based royalties are recorded based on estimated quarterly net sales of the associated collaboration products. Differences between actual results and estimated amounts are adjusted for in the period in which they become known, which typically follows the quarterly period in which the estimate was made. To date, actual royalties received have not differed materially from our estimates. Concentration of Credit Risk. Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash, cash equivalents and marketable securities. We have established guidelines to limit our exposure to credit risk by diversifying our investment portfolio and by placing investments with high credit quality financial institutions and maturities that maintain safety and liquidity. To date, we have not experienced any credit losses and do not believe we are exposed to any significant credit risk in relation to these financial instruments. We are also subject to credit risk from our accounts receivable related to our product sales. Our two largest customers represented approximately 86% of our product revenues for both 2020 and 2019, and the significant majority of our accounts receivable balances at December 31, 2020 and 2019. For 2018, our three largest customers represented approximately 93% of our product revenue and substantially all of our accounts receivable balance at December 31, 2018. To date, we have not experienced any significant losses with respect to the collection of these accounts receivable. Cost of Sales. Cost of sales includes third-party manufacturing, transportation, freight and indirect overhead costs associated with the manufacture and distribution of INGREZZA and ONGENTYS, royalty fees on net sales of ORILISSA and ORIAHNN, and adjustments for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand. Research and Development Expenses. R&D expenses consist primarily of salaries, payroll taxes, employee benefits and share-based compensation charges for those individuals involved in ongoing R&D efforts; as well as scientific consulting fees, preclinical and clinical trial costs, R&D facilities costs, laboratory supply costs and depreciation of scientific equipment. All such costs are charged to R&D expense as incurred. These expenses result from our independent R&D efforts, as well as efforts associated with collaborations, in-licenses and third-party funded research arrangements, including event based milestones. Asset Acquisitions. We account for acquisitions of an asset or group of assets that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the assets acquired on the basis of their relative fair values. No goodwill is recognized in an asset acquisition. Intangible assets that are acquired in an asset acquisition for use in R&D activities which have no alternative future use are expensed as in-process research and development, or IPR&D, on the acquisition date. Future costs to develop these assets are recorded to R&D expense as they are incurred. Advertising Expense. Advertising costs are expensed when services are performed, or goods are delivered. We incurred advertising costs related to INGREZZA and ONGENTYS of $64.8 million for 2020, $40.6 million for 2019 and $20.5 million for 2018. Share-Based Compensation. We grant stock options to purchase our common stock to eligible employees and directors and also grant certain employees restricted stock units, or RSUs, and performance-based restricted stock units, or PRSUs. Additionally, we allow employees to participate in an employee stock purchase plan, or ESPP. We estimate the fair value of stock options and shares to be issued under the ESPP using the Black-Scholes option-pricing model on the date of grant. Restricted stock units are valued based on the closing price of our common stock on the date of grant. The fair value of equity instruments expected to vest are recognized and amortized on a straight-line basis over the requisite service period of the award, which is generally three to four years; however, certain provisions in our equity compensation plans provide for shorter vesting periods under certain circumstances. The fair value of shares to be issued under the ESPP are recognized and amortized on a straight-line basis over the purchase period, which is generally six months. Additionally, we granted certain PRSUs that vest upon the achievement of certain predefined company-specific performance-based criteria. Expense related to these PRSUs is generally recognized ratably over the expected performance period once the predefined performance-based criteria for vesting becomes probable. Income Taxes. Our income tax benefit (provision) is computed under the asset and liability method. Significant estimates are required in determining our income tax benefit (provision). Some of these estimates are based on interpretations of existing tax laws or regulations. We recognize deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined on the basis of the difference between the tax basis of assets and liabilities and their respective financial reporting amounts (temporary differences) at enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is established for deferred tax assets for which it is more likely than not that some portion or all of the deferred tax assets, including net operating losses and tax credits, will not be realized. We periodically re-assess the need for a valuation allowance against our deferred tax assets based on various factors including our historical earnings experience by taxing jurisdiction, and forecasts of future operating results and utilization of net operating losses and tax credits prior to their expiration. Significant judgment is required in making this assessment and, to the extent that a reversal of any portion of our valuation allowance against our deferred tax assets is deemed appropriate, a tax benefit will be recognized against our income tax provision in the period of such reversal. Prior to 2020, we recorded a valuation allowance that fully offset our deferred tax assets. On December 31, 2020, based on our evaluation of various factors, such as our achievement of a cumulative three-year income position as of December 31, 2020, as well as our consideration of forecasts of future operating results and utilization of net operating losses and tax credits prior to their expiration, we released substantially all of our valuation allowance against our deferred tax assets and recorded a corresponding income tax benefit. Refer to Note 9 to the consolidated financial statements for more information. We recognize tax benefits from uncertain tax positions only if it is more likely than not that the tax position will be sustained upon examination by the tax authorities based on the technical merits of the position. An adverse resolution of one or more of these uncertain tax positions in any period could have a material impact on the results of operations for that period. Net Income Per Share. Basic net income per share is computed using the weighted average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common and potentially dilutive shares outstanding during the period, including the potentially dilutive shares resulting from the conversion of the 2024 Notes and excluding the effect of stock options and restricted stock outstanding for periods when their effect is anti-dilutive, using the treasury stock method. Convertible debt instruments that may be settled entirely or partly in cash (such as the 2024 Notes) may, in certain circumstances where the borrower has the ability and intent to settle in cash, be accounted for under the treasury stock method. We issued the 2024 Notes with a combination settlement feature, which we have the ability and intent to use upon conversion of the 2024 Notes, to settle the principal amount of debt for cash and the excess of the principal portion in shares of our common stock. As a result, of the approximately 5.0 million shares underlying the 2024 Notes at December 31, 2020, only the shares required to settle the excess of the principal portion would be considered dilutive under the treasury stock method. Further, approximately 0.2 million PRSUs were excluded from the calculation of diluted net income per share as the performance condition has not been achieved. In loss periods, basic net loss per share and diluted net loss per share are identical because the otherwise dilutive potential common shares become anti-dilutive and are therefore excluded. Recently Adopted Accounting Pronouncements. ASU 2016-13. 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, 2020, including 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 ASU 2019-12 will have on our condensed consolidated financial statements and related disclosures. ASU 2020-06. In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments, and amends existing earnings-per-share, or EPS, guidance by requiring that an entity use the if-converted method when calculating diluted EPS for convertible instruments. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years, with early adoption permitted for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We plan to adopt ASU 2020-06 effective January 1, 2022 and are currently evaluating the effect ASU 2020-06 will have on our consolidated financial statements and related disclosures.

License and Collaboration Agreements	12 Months Ended
License and Collaboration Agreements	Dec. 31, 2020
Business Combinations [Abstract]
Commitments and Contingencies	Under the terms of the following license and collaboration agreements, we may be required to make milestone payments upon achievement of certain development and regulatory activities of up to $8.5 billion and pay royalties on future sales, if any, of commercial products resulting from these agreements.
License and Collaboration Agreements	License and Collaboration Agreements Takeda Pharmaceutical Company Limited. We entered into an exclusive license agreement with Takeda Pharmaceutical Company Limited, or Takeda, which became effective in July 2020, 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, (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. NBI-1065844 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 NBI-1065844 before we initiate a Phase III clinical trial. 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, which, including certain transaction related costs, was expensed as in-process research and development, or IPR&D, in the third quarter of 2020. Pursuant to the terms of the agreement, Takeda may also be entitled to receive additional payments of up to $1.9 billion upon the achievement of certain event-based milestones associated with Royalty-Bearing Products, as well as receive royalties on the 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. Idorsia Pharmaceuticals Ltd. In May 2020, we entered a collaboration and licensing agreement with Idorsia Pharmaceuticals Ltd, or Idorsia, to license the global rights 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 also includes a research collaboration to discover and identify additional novel T-type calcium channel blockers as development candidates. In connection with the exercise of the option, we paid Idorsia $45.0 million upfront, which we 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 we recorded as a prepaid asset and is being 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 additional payments of up to $365.0 million with respect to NBI-827104 and $620.0 million with respect to the development candidates. Idorsia may also be entitled to receive additional payments of up to $750.0 million upon the achievement of certain commercial milestones, as well as receive royalties on the future net sales of any collaboration product. Further, we will be responsible for all manufacturing, development and commercialization costs of any collaboration product. Xenon Pharmaceuticals, Inc. 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 (XEN901) and three preclinical candidates, which compounds we will have the exclusive right to further develop and commercialize under the terms and conditions set forth in the agreement. We will be solely responsible, at our sole cost and expense, for all development and manufacturing of the compounds and any pharmaceutical product that contains a compound, subject to Xenon’s right to elect to co-fund the development of one product in a major indication and thus receive a mid-single digit percentage increase in royalties owed on the net sales of such product in the U.S. If Xenon exercises such option, the parties will share equally all reasonable and documented costs and expenses incurred in connection with the development of such product in the applicable indication, except costs and expenses that are solely related to the development of such product for regulatory approval outside the U.S. In connection with the agreement, we paid Xenon $30.0 million upfront and purchased $20.0 million of Xenon’s common stock at $14.196 per share, representing approximately 1.4 million shares. Pursuant to the terms of the agreement, Xenon may also be entitled to receive additional payments of up to $1.7 billion upon the achievement of certain event-based milestones, as well as receive royalties on the future 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. Voyager Therapeutics, Inc. We entered into a collaboration and license agreement with Voyager Therapeutics, Inc., or Voyager, which became effective in March 2019, to develop and commercialize four programs using Voyager’s proprietary gene therapy platform. The four programs consist of the NBIb-1817 (VY-AADC) program for Parkinson’s disease, the Friedreich’s ataxia program and the rights to two undisclosed programs. In connection with the agreement, we paid Voyager $115.0 million upfront and purchased $50.0 million of Voyager’s common stock at $11.9625 per share, representing approximately 4.2 million shares. Pursuant to the terms of the agreement, Voyager may also be entitled to receive additional payments of up to $1.7 billion upon the achievement of certain event-based milestones, as well as receive royalties on the future net sales of any collaboration product. Pursuant to development plans agreed to by us and Voyager, unless Voyager exercises its co-development and co-commercialization rights as provided for in the agreement, we will be responsible for all development costs. Further, upon the occurrence of a specified event for each program, we will assume responsibility for the development, manufacturing, and commercialization activities of such program. We accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business. Our equity investment in Voyager was recorded at a fair value of $54.7 million after considering Voyager’s stock price on the date of closing and certain lock-up and voting provisions applicable to the acquired shares. The remaining $113.1 million of the purchase price, which includes the applicable transaction costs, was expensed as in-process research and development, or IPR&D, in the first quarter of 2019. In June 2019, we entered into an amendment to the collaboration and license agreement with Voyager. Under the terms of the amendment, we paid Voyager $5.0 million upfront to obtain rights outside the U.S. to the Friedreich’s ataxia program in connection with the early return of those rights to Voyager pursuant to a restructuring of Voyager’s gene therapy relationship with Sanofi Genzyme. The upfront payment was expensed as IPR&D in the second quarter of 2019. BIAL – Portela & Ca, S.A. We acquired the U.S. and Canada rights to ONGENTYS® from BIAL in the first quarter of 2017. We launched ONGENTYS in the U.S. in September 2020, after receiving FDA approval for ONGENTYS as an adjunctive therapy to levodopa/DOPA decarboxylase inhibitors in adult Parkinson's disease patients in April 2020. FDA approval for ONGENTYS for Parkinson’s disease resulted in a $20.0 million event-based payment to BIAL, which we expensed as R&D in the second quarter of 2020. We further recognized R&D expense of $10.0 million in each 2019 and 2018 in connection with BIAL’s achievement of certain regulatory event-based milestones related to then ongoing development of ONGENTYS. Pursuant to the terms of the agreement, BIAL may also be entitled to receive additional payments of up to $75.0 million upon the achievement of certain event-based milestones. Under the terms of the agreement, we are responsible for the commercialization of ONGENTYS in the U.S. and Canada. Further, we 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 determined 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. 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. 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 and $15.0 million associated with the achievement of a certain event-based milestone. We further recognized revenue of $2.7 million in 2020 and $0.9 million in 2019 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, $6.7 million of the $30.0 million upfront payment received from MTPC is being deferred and will be recognized as revenue over the ongoing study period using an input method according to costs incurred to-date relative to estimated total costs associated with the study. Pursuant to the terms of the agreement, we may also be entitled to receive additional payments of up to $70.0 million upon the achievement of certain event-based milestones, receive payments for the manufacture of certain pharmaceutical products, as well as receive royalties on the future net sales of any collaboration product 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. AbbVie Inc. In June 2010, we entered into an exclusive worldwide collaboration with AbbVie Inc., or AbbVie, to develop and commercialize elagolix and all next-generation gonadotropin-releasing factor, or GnRH, antagonists and collectively, GnRH Compounds, for women’s and men’s health. AbbVie received approval for 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 FDA approval for ORIAHNN for the management of heavy menstrual bleeding associated with uterine fibroids in pre-menopausal women. We recognized sales-based royalties on AbbVie net sales of ORILISSA and ORIAHNN of $19.2 million in 2020, $14.3 million in 2019 and $1.6 million in 2018. FDA approval for ORIAHNN for uterine fibroids resulted in the achievement of a $30.0 million event-based milestone, which we recognized as collaboration revenue in the second quarter of 2020. In 2019, we recognized collaboration revenue of $20.0 million in connection with the FDA’s acceptance of AbbVie’s NDA submission for the approval of ORIAHNN for uterine fibroids. In 2018, we recognized collaboration revenue of $40.0 million in connection with the FDA’s approval for ORILISSA for endometriosis. 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 event-based milestones. Pursuant to the terms of the agreement, we may also be entitled to receive additional payments of up to $366.0 million upon the achievement of certain event-based milestones. Under the terms of the agreement, AbbVie is responsible for all third-party development, marketing, and commercialization costs. We are entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights.
Subsequent Events	On February 2, 2021, we notified Voyager of our termination of the NBIb-1817 for Parkinson’s disease program. The effective date of this termination will be August 2, 2021. The termination does not apply to any other development program other than NBIb-1817 for Parkinson’s disease, and our collaboration and license agreement with Voyager will otherwise continue in effect.

Debt Securities

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Debt Securities

The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive income (loss), allowance for credit losses, and fair value of debt securities available-for-sale at December 31, 2020, aggregated by major security type and contractual maturity:


(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss		Allowance for Credit Losses		Fair Value
Commercial paper	Within 1 year	$	82.2	$	—	$	—	$	—	$	82.2
Corporate debt securities	Within 1 year	299.3		1.4		—		—		300.7
Securities of government-sponsored entities	Within 1 year	230.9		0.1		—		—		231.0
		$	612.4	$	1.5	$	—	$	—	$	613.9

Corporate debt securities	1 to 2 years	$	144.8	$	0.4	$	—	$	—	$	145.2
Securities of government-sponsored entities	1 to 2 years	81.9		0.1		(0.1)		—		81.9
		$	226.7	$	0.5	$	(0.1)	$	—	$	227.1

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 Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
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

The following table summarizes debt securities available-for-sale in an unrealized loss position for which an allowance for credit losses has not been recorded at December 31, 2020, 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 Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Securities of government-sponsored entities	$	95.0	$	(0.1)	$	—	$	—	$	95.0	$	(0.1)

At December 31, 2020, our security portfolio consisted of 148 securities related to investments in debt securities available-for-sale, of which 30 securities were in an unrealized loss position.

Our investments in corporate debt securities in an unrealized loss position at December 31, 2020 are of high credit quality (rated A or higher). 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 Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate debt securities	$	186.1	$	(0.1)	$	—	$	—	$	186.1	$	(0.1)

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

Investments at December 31, 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	$	187.1	$	187.1	$	—	$	—
Total cash and cash equivalents	187.1		187.1		—		—
Restricted cash:
Certificates of deposit	3.2		3.2		—		—
Total restricted cash	3.2		3.2		—		—
Debt securities available-for-sale:
Commercial paper	82.2		—		82.2		—
Corporate debt securities	445.9		—		445.9		—
Securities of government-sponsored entities	312.9		—		312.9		—
Total debt securities available-for-sale	841.0		—		841.0		—
Equity securities:
Equity securities–biotechnology industry	38.2		—		—		38.2
Total equity securities	38.2		—		—		38.2
Total recurring fair value measurements	$	1,069.5	$	190.3	$	841.0	$	38.2

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 securities, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3):


	Year Ended December 31,
(in millions)	2020		2019		2018
Beginning balance	$	55.9	$	—	$	—
Purchases	—		68.9		—
Unrealized loss included in earnings	(17.7)		(13.0)		—
Ending balance	$	38.2	$	55.9	$	—

At December 31, 2020, the discount for lack of marketability used in the valuation analysis of equity securities ranged from 15.0% to 34.0% (weighted average of 24.8%). The discount for lack of marketability was weighted by the relative fair value of the instruments. A significant increase (decrease) in the discount for lack of marketability in isolation would result in a significantly lower (higher) fair value measurement. Unrealized gains and losses on equity securities are included in other income (expense), net.

- Definition

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

+ References + Details

Convertible Senior Notes

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Convertible Senior Notes

On May 2, 2017, we completed a private placement of $517.5 million in aggregate principal amount of 2.25% convertible senior notes due 2024, or the 2024 Notes, and entered into an indenture agreement, 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 5 business-day period immediately after any 5 consecutive trading-day period (the measurement period) in which the trading price (as defined in the 2024 Indenture) per $1,000 principal amount of the

2024 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such trading day;

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

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

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

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 notes. The conversion value is the sum of the daily conversion value which is the product of the effective conversion rate divided by 25 days and the daily 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 5.0 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 outstanding principal value and any conversion premium in any combination of cash and shares of its 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 their 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 December 31, 2020, the remaining period over which the discount on the liability component will be amortized was approximately 3.4 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.

In November 2020, we entered into separate, privately negotiated transactions with certain holders of the 2024 Notes to repurchase $136.2 million aggregate principal amount of the 2024 Notes for an aggregate repurchase price of $186.9 million in cash. We accounted for the partial repurchase of the 2024 Notes as a debt extinguishment. As a result, we attributed $130.7 million of the aggregate repurchase price to the liability component based on the fair value of the liability component immediately before extinguishment. The fair value of the liability component was calculated at settlement using a discounted cash flow analysis with a discount rate of 3.37%, which was the market rate for similar notes that have no conversion rights. The difference of $56.3 million between the fair value of the aggregate consideration remitted to certain holders of the 2024 Notes and the fair value of the liability component was attributed to the reacquisition of the equity component and recognized as a reduction to additional paid-in capital. The carrying amount of the liability of $112.4 million at settlement was recognized as a reduction to convertible senior notes and resulted in an $18.4 million loss on extinguishment.

The 2024 Notes, net of discounts and deferred financing costs, consisted of the following:


	December 31,
(in millions)	2020		2019
Principal	$	381.3	$	517.5
Deferred financing costs	(4.0)		(6.9)
Debt discount, net	(59.4)		(101.8)
Net carrying amount	$	317.9	$	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 $514.3 million and $596.8 million at December 31, 2020 and 2019, respectively.

Other Balance Sheet Details

12 Months Ended

Dec. 31, 2020

Other Balance Sheet Details [Abstract]

Other Balance Sheet Details

Inventories consisted of the following:


	December 31,
(in millions)	2020		2019
Raw materials	$	16.6	$	14.1
Work in process	2.4		1.5
Finished goods	9.0		1.7
Total inventories	$	28.0	$	17.3

Property and equipment, net, consisted of the following:


	December 31,
(in millions)	2020		2019
Tenant improvements	$	29.5	$	26.3
Scientific equipment	39.2		33.5
Computer equipment	13.9		12.5
Furniture and fixtures	3.7		3.2
	86.3		75.5
Less accumulated depreciation	(41.7)		(33.6)
Total property and equipment, net	$	44.6	$	41.9

Accounts payable and accrued liabilities consisted of the following:


	December 31,
(in millions)	2020		2019
Accrued employee related costs	$	38.2	$	38.9
Revenue-related reserves for discounts and allowances	34.6		30.6
Accrued development costs	32.9		25.5
Accrued Branded Prescription Drug Fee	23.6		4.9
Accounts payable and other accrued liabilities	39.4		41.4
Total accounts payable and accrued liabilities	$	168.7	$	141.3

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


	December 31,
(in millions)	2020		2019
Cash and cash equivalents	$	187.1	$	112.3
Restricted cash	3.2		3.2
Total cash, cash equivalents and restricted cash	$	190.3	$	115.5

Net Income Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Income Per Share

Net income per share was calculated as follows:


	Year Ended December 31,
(in millions, except per share data)	2020		2019		2018
Net income - basic and diluted	$	407.3	$	37.0	$	21.1
Weighted-average common shares outstanding:
Basic	93.1		91.6		90.2
Effect of dilutive securities:

Stock options	2.4		2.6		3.2
Restricted stock units	0.5		0.4		0.6
2024 Notes	1.8		1.1		1.3
Diluted	97.8		95.7		95.4
Net income per share:
Basic	$	4.38	$	0.40	$	0.23
Diluted	$	4.16	$	0.39	$	0.22

Shares which have been excluded from diluted per share amounts because their effect would have been anti-dilutive were 2.5 million, 2.1 million and 0.9 million for 2020, 2019 and 2018, respectively.

Share-Based Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Share-Based Compensation

In May 2011, we adopted the 2011 Equity Incentive Plan, as amended, or the 2011 Plan. The 2011 Plan authorized 21 million shares of common stock for issuance and allowed for the grant of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, or RSUs, performance stock awards, performance-based restricted stock units, or PRSUs, and certain other awards. During 2020, the 2011 Plan was merged into the 2020 Plan (defined below). As a result, there were no shares of common stock remaining available for future grant under the 2011 Plan.

In May 2018, we adopted the 2018 Employee Stock Purchase Plan, or ESPP, pursuant to which 0.3 million shares of common stock are authorized for issuance. At December 31, 2020, 0.2 million shares of common stock remain available for future grant under the 2018 ESPP.

In May 2020, we adopted the 2020 Equity Incentive Plan, or the 2020 Plan. The 2020 Plan authorized 3.3 million shares of common stock for issuance and allows for the grant of stock options, stock appreciation rights, restricted stock awards, RSUs, performance stock awards, PRSUs and certain other awards. The 2011 Plan was merged into the 2020 Plan and, as a result, all remaining shares in the 2011 Plan were transferred into the 2020 Plan. At December 31, 2020, 8.2 million shares of common stock remain available for future grant under the 2020 Plan.

Share-Based Compensation Expense. The effect of share-based compensation expense on our consolidated statements of income and comprehensive income by line-item follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Selling, general and administrative expense	$	66.3	$	49.5	$	31.9
Research and development expense	33.7		25.8		26.2
Total share-based compensation expense	$	100.0	$	75.3	$	58.1

Share-based compensation expense by award-type follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Stock options	$	47.5	$	36.5	$	35.4
RSUs	44.2		30.5		21.9
PRSUs	5.3		5.6		—
ESPP	3.0		2.7		0.8
Total share-based compensation expense	$	100.0	$	75.3	$	58.1

At December 31, 2020, unrecognized share-based compensation expense by award-type and the weighted-average period over which such expense is expected to be recognized, as applicable, were as follows:


(dollars in millions)	Unrecognized Expense		Weighted-Average Recognition Period
Stock options	$	86.2	2.3 years
RSUs	$	99.5	2.3 years

Stock Options. Typically, stock options have a ten-year term and vest over a three to four-year period. The exercise price of stock options granted is equal to the closing price of our common stock on the date of grant. We estimate the fair value of stock options using the Black-Scholes option-pricing model on the date of grant. The Black-Scholes option-pricing model incorporates various and highly sensitive assumptions including expected volatility, term and interest rates. The weighted-average grant-date fair values of stock options granted were $45.67, $41.74 and $43.42 for 2020, 2019 and 2018, respectively.

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


	Year Ended December 31,
	2020		2019		2018
Risk-free interest rate	1.4	%	2.4	%	2.5	%
Expected volatility of common stock	48.5	%	54.8	%	59.5	%
Dividend yield	0.0	%	0.0	%	0.0	%
Expected option term	5.3 years		5.4 years		4.7 years

The weighted-average valuation assumptions were determined as follows:

•The expected volatility of common stock is estimated based on the historical volatility of our common stock over the most recent period commensurate with the estimated expected term of our stock options.

•The expected option term is estimated based on historical experience as well as the status of the employee. For example, directors and officers have a longer expected option term than all other employees.

•The risk-free interest rate for periods within the contractual life of a stock option is based upon observed interest rates appropriate for the expected term of our employee stock options.

•We have not historically declared or paid dividends and do not intend to do so in the foreseeable future.

A summary of activity related to stock options follows:


(in millions, except weighted average data)	Number of Stock Options	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2019	6.1	$	52.62
Granted	1.3	$	103.44
Exercised	(0.6)	$	43.90
Canceled	—	$	—
Outstanding at December 31, 2020	6.8	$	62.98	6.4 years	$	235.4
Exercisable at December 31, 2020	4.7	$	49.80	5.5 years	$	218.2

The total intrinsic value of stock options exercised during 2020, 2019 and 2018 was $40.2 million, $64.3 million and $117.0 million, respectively. Cash received from stock option exercises during 2020, 2019 and 2018 was $23.5 million, $27.3 million and $29.5 million, respectively.

Restricted Stock Units. Typically, RSUs vest over a four-year period. The fair value of RSUs is based on the closing sale price of our common stock on the date of issuance. RSUs may be subject to a deferred delivery arrangement at the election of eligible employees.

A summary of activity related to RSUs follows:


(in millions, except weighted average data)	Number of RSUs	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Unvested at December 31, 2019	1.4	$	74.77
Granted	0.7	$	102.92
Released	(0.5)	$	67.86
Canceled	(0.1)	$	84.95
Unvested at December 31, 2020	1.5	$	89.60	1.3 years	$	147.5

The total fair value of RSUs that vested during 2020, 2019 and 2018 was $49.7 million, $36.1 million and $35.5 million, respectively.

Performance-Based Restricted Stock Units. PRSUs vest based on the achievement of certain predefined Company-specific performance criteria and expire four to five years from the grant date. The fair value of PRSUs is estimated based on the closing sale price of our common stock on the date of grant. Expense recognition for PRSUs commences when attainment of the performance-based criteria is determined to be probable.

A summary of activity related to PRSUs follows:


(in millions, except weighted average data)	Number of PRSUs	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Unvested at December 31, 2019	0.3	$	59.62
Granted	0.2	$	102.90
Released	(0.1)	$	82.04
Canceled	(0.2)	$	45.67
Unvested at December 31, 2020	0.2	$	102.90	2.2 years	$	15.8

At December 31, 2020, unrecognized share-based compensation expense for PRSUs was $17.0 million. The total fair value of PRSUs that vested during 2020 was $13.5 million. No PRSUs vested during 2019 or 2018.

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

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

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


	Year Ended December 31,
(in millions)	2020		2019		2018
Current:
Federal	$	—	$	—	$	(0.1)
State	10.1		9.5		0.8
Total current taxes	10.1		9.5		0.7
Deferred:
Federal	(287.5)		—		—
State	(23.2)		—		—
Total deferred taxes	(310.7)		—		—
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7

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


	Year Ended December 31,
(in millions)	2020		2019		2018
Federal income taxes at 21% for 2020, 2019, 2018	$	22.4	$	9.8	$	4.6
State income tax, net of federal benefit	5.5		4.0		0.4
Non-deductible expenses	0.6		0.8		0.4
Branded prescription drug fee	4.9		3.7		—
Share-based compensation expense	(6.7)		(12.8)		(9.8)
Officer compensation	3.7		3.1		0.9
Change in tax rate	3.3		(4.1)		(0.2)
Expired tax attributes	1.1		1.2		13.9
Research credits	(39.0)		(10.4)		(13.5)
Change in valuation allowance	(296.3)		13.9		4.3
Other	(0.1)		0.3		(0.3)
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7

Significant components of our deferred tax assets as of December 31, 2020 and 2019 are listed below.


	December 31,
(in millions)	2020		2019
Deferred tax assets:
Net operating losses	$	111.4	$	181.3
Research and development credits	109.6		71.9
Capitalized research and development	24.7		28.0
Share-based compensation expense	29.8		22.9
Operating lease assets	25.2		23.3
Intangible assets	86.7		49.3
Other	23.9		18.5
Total deferred tax assets	411.3		395.2
Deferred tax liabilities:
Convertible senior notes	(13.8)		(24.1)
Operating lease liabilities	(19.9)		(18.2)
Other	(8.4)		(6.9)
Total deferred tax liabilities	(42.1)		(49.2)
Net of deferred tax assets and liabilities	369.2		346.0
Valuation allowance	(49.8)		(346.0)
Net deferred tax assets	$	319.4	$	—

At December 31, 2020, our deferred tax assets were primarily the result of federal net operating loss carry forwards, capitalized research costs, acquired intangible assets and tax credit carryforwards. At December 31, 2020 and 2019, we recorded a valuation allowance of $49.8 million and $346.0 million, respectively, against our gross deferred tax asset balance.

At each reporting date, management considers new evidence, both positive and negative, that could affect its assessment of the future realizability of our deferred tax assets. At December 31, 2020, in part because we achieved three years of cumulative pretax income, management determined there is sufficient positive evidence to conclude that it is more likely than not deferred tax assets of $319.4 million are realizable. Accordingly, we recorded a net valuation release of $296.3 million on the basis of management’s assessment. The remaining valuation allowance of $49.8 million consists primarily of state net operating loss and credit carryforwards for which management cannot conclude it is more likely than not to be realized. The release of the valuation allowance is reported under continuing operations as a benefit to income tax expense.

At December 31, 2020, we had federal and state income tax net operating loss carryforwards of $518.2 million and $340.8 million, respectively. The federal net operating losses will begin to expire in 2028, unless previously utilized.

California net operating losses will begin to expire in 2028 unless previously utilized and the net operating losses related to other states will begin to expire in 2026.

In addition, we have federal and California R&D tax credit carryforwards of $92.1 million and $56.4 million, respectively. A portion of the federal R&D tax credit carryforwards expired in 2020. The remaining federal R&D tax credits will continue to expire beginning in 2021, unless previously utilized. The California R&D tax credits carry forward indefinitely.

Additionally, the future utilization of our net operating loss and R&D tax credit carryforwards to offset future taxable income may be subject to an annual limitation, pursuant to Internal Revenue Code Sections 382 and 383, as a result of ownership changes that could occur in the future. No ownership changes have occurred through December 31, 2020.

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

Our policy is to recognize interest or penalties related to income tax matters in income tax expense. Interest and penalties related to income tax matters were not material for 2020, 2019 or 2018.

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

A summary of activity related to unrecognized tax benefits follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Balance at January 1	$	63.9	$	54.8	$	37.4
(Decrease) increase related to prior year tax positions	(5.7)		0.3		6.1
Increase related to current year tax positions	3.9		9.5		11.7
Settlements related to prior year tax positions	(0.2)		—		—
Expiration of the statute of limitations for the assessment of taxes	(1.1)		(0.7)		(0.4)
Balance at December 31	$	60.8	$	63.9	$	54.8

We excluded those deferred tax assets that are not more-likely-than-not to be sustained under the technical merits of the tax position. Such unrecognized tax benefits total $3.9 million for current year tax positions, as reflected in the table above.

At December 31, 2020, we had $53.9 million of unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate, subject to the valuation allowance. We do not expect a significant change in our unrecognized tax benefits in the next twelve months.

- Definition

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

+ References + Details

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

We have operating leases for our office and laboratory facilities, including our corporate headquarters, with terms that expire from 2025 through 2031. We have two options to extend the term of the operating lease for our corporate headquarters for a period of ten years each. However, as we were not reasonably certain to exercise either of those options at lease commencement, neither option was recognized as part of the associated operating lease right-of-use, or ROU, asset or liability. 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 $10.1 million for 2020 and $8.1 million for 2019. Cash paid for amounts included in the measurement of lease liabilities was $8.6 million for 2020 and $7.7 million for 2019.

Our operating leases had a weighted-average remaining lease term of approximately 10.3 years and 11.2 years at December 31, 2020 and 2019, respectively, and a weighted-average discount rate of 5.6% and 5.8% at December 31, 2020 and 2019, respectively.

Approximate future minimum lease payments under operating leases were as follows:


(in millions)	December 31, 2020
Year ending December 31, 2021	$	10.7
Year ending December 31, 2022	12.4
Year ending December 31, 2023	12.7
Year ending December 31, 2024	13.1
Year ending December 31, 2025	13.5
Thereafter	77.5
Total operating lease payments	139.9
Less accreted interest	35.2
Total operating lease liabilities	104.7
Less current operating lease liabilities	10.3
Noncurrent operating lease liabilities	$	94.4

Note 1: Amounts presented in the table above exclude $19.7 million of non-cancelable future minimum lease payments for operating leases that have not yet commenced.

Note 2: Current operating lease liabilities are included in other current liabilities on the consolidated balance sheets.

Retirement Plan	12 Months Ended
Retirement Plan	Dec. 31, 2020
Retirement Benefits [Abstract]
Retirement Plan	Retirement PlanWe have a 401(k) defined contribution savings plan, or the 401(k) Plan. The 401(k) Plan is for the benefit of all qualifying employees and permits voluntary contributions by employees up to 60% of base salary limited by the IRS-imposed maximum. Employer contributions were $6.7 million, $4.9 million, and $1.8 million for 2020, 2019 and 2018, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

A summary of our quarterly results follows:


(in millions, except per share data)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
Year Ended December 31, 2020:
Total revenues	$	237.1	$	302.4	$	258.5	$	247.9
Total operating expenses (1)	$	178.2	$	225.8	$	302.8	$	176.1
Net income (loss) (1)	$	37.4	$	79.6	$	(57.6)	$	347.9
Net income (loss) per share, basic (1)	$	0.40	$	0.86	$	(0.62)	$	3.72
Net income (loss) per share, diluted (1)	$	0.39	$	0.81	$	(0.62)	$	3.58
Weighted average common shares outstanding, basic	92.6		93.0		93.3		93.5
Weighted average common shares outstanding, diluted	97.0		98.2		93.3		97.2

Year Ended December 31, 2019:
Total revenues	$	138.4	$	183.5	$	222.1	$	244.1
Total operating expenses (2)	$	239.4	$	149.1	$	132.0	$	195.3
Net (loss) income (2)	$	(102.1)	$	51.3	$	53.8	$	34.0
Net (loss) income per share, basic (2)	$	(1.12)	$	0.56	$	0.59	$	0.37
Net (loss) income per share, diluted (2)	$	(1.12)	$	0.54	$	0.56	$	0.35
Weighted average common shares outstanding, basic	91.1		91.4		91.9		92.2
Weighted average common shares outstanding, diluted	91.1		94.8		96.1		97.2

(1) In connection with the payment of the upfront fee pursuant to our collaboration and license agreement with Idorsia, we recorded a charge of $46.0 million, accounted for as IPR&D, in the second quarter of 2020. In connection with the payment of the upfront fee pursuant to our collaboration with Takeda, we recorded a charge of $118.5 million, accounted for as IPR&D, in the third quarter of 2020.

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

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Business Activities	Business Activities. Neurocrine Biosciences, Inc., or Neurocrine, the Company, we, our or us, was incorporated in California in 1992 and reincorporated in Delaware in 1996. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of Neurocrine. We also have two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. both of which were formed in December 2014 and are inactive. We are a neuroscience-focused biopharmaceutical company dedicated to discovering, developing and delivering life-changing treatments for patients with serious, challenging and under-addressed neurological, endocrine and psychiatric disorders. Our diverse portfolio includes FDA-approved treatments for tardive dyskinesia, Parkinson’s disease, endometriosis, uterine fibroids and clinical programs in multiple therapeutic areas. For nearly three decades, we specialize in targeting and interrupting disease-causing mechanisms involving the interconnected pathways of the nervous and endocrine systems. (*in collaboration with AbbVie Inc.)
Principles of Consolidation	Principles of Consolidation. The consolidated financial statements include the accounts of Neurocrine as well as our wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, or GAAP, requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates.
Industry Segment and Geographic Information	Industry Segment and Geographic Information. We operate in a single industry segment – the discovery, development and marketing of pharmaceuticals for the treatment of neurological, endocrine and psychiatric-based diseases and disorders. We had no foreign-based operations during any of the years presented.
Reclassifications	Reclassifications. Certain amounts in prior year periods have been reclassified to conform with the presentation adopted in the current year.
Cash Equivalents	Cash Equivalents. We consider all highly liquid investments that are readily convertible into cash and have an original maturity of three months or less at the time of purchase to be cash equivalents.
Accounts Receivable	Accounts Receivable. Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks and any allowance for doubtful accounts. We estimate the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of our customers and individual customer circumstances. To date, an allowance for doubtful accounts has not been material.
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 December 31, 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 2020, 2019 or 2018.
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. There were no transfers between levels in the fair value hierarchy during 2020 or 2019.
Inventory	Inventory. Inventory is valued at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on the first-in, first-out method. We assess the valuation of our inventory on a quarterly basis and adjust the value for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand. Inventory costs resulting from these adjustments are recognized as cost of sales in the period in which they are incurred. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, we capitalize pre-launch inventory costs prior to regulatory approval.
Property and Equipment	Property and Equipment. Property and equipment are stated at cost and depreciated over the estimated useful lives of the assets using the straight-line method. Equipment is depreciated over an average estimated useful life of three to seven years. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the remaining lease term. Depreciation expense was $8.6 million for 2020, $7.4 million for 2019 and $4.0 million for 2018.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If the carrying amount is not recoverable, we measure the amount of any impairment by comparing the carrying value of the asset to the present value of the expected future cash flows associated with the use of the asset.
Revenue Recognition	Revenue Recognition. We recognize revenue when the customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. Revenue is recognized using a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. Product Sales, Net. In the U.S., our product sales, net consist of sales of INGREZZA, primarily to specialty pharmacy providers and a specialty distributor, and sales of ONGENTYS, primarily to wholesale distributors. We recognize product sales, net when the customer obtains control of our product, which occurs at a point in time, typically upon delivery of our product to the customer. Revenues from product sales are recorded net of reserves established for applicable discounts and allowances that are offered within contracts with our customers, payors and other third parties. Such estimates are based on information received from external sources (such as written or oral information obtained from our customers with respect to their period-end inventory levels and sales to end-users during the reporting period), as supplemented by management’s judgement. Our process for estimating reserves established for these variable consideration components does not differ materially from historical practices. The transaction price, which includes variable consideration reflecting the impact of discounts and allowances, may be subject to constraint and is included in the net sales price only to the extent that it is probable that a significant reversal of the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts may ultimately differ from our estimates. If actual results vary, we adjust these estimates, which could have an effect on earnings in the period of adjustment. Our significant categories of sales discounts and allowances are as follows: Product Discounts. Product discounts are based on payment terms extended to our customers at the time of sale, which include incentives offered for prompt payment. We maintain a reserve for product discounts based on our historical experience, including the timing of customer payments. To date, actual product discounts have not differed materially from our estimates. Government Rebates. We are obligated to pay rebates for mandated discounts under the Medicaid Drug Rebate Program. The liability for such rebates consists of invoices received for claims from prior quarters that remain unpaid, or for which an invoice has not been received, and estimated rebates for the current applicable reporting period. Such estimates are based on actual historical rebates by state, estimated payor mix, state and federal regulations and relevant contractual terms, as supplemented by management’s judgement. Our rebate accrual calculations require us to project the magnitude of our sales, by state, that will be subject to these rebates. There is a significant time-lag in our receiving rebate notices from each state (generally, several months or longer after a sale is recognized). Estimated rebates are recorded as a reduction of revenue in the period the related sale is recognized. To date, actual government rebates have not differed materially from our estimates. Chargebacks. The difference between the list price, or the price at which we sell our products to our customers, and the contracted price, or the price at which our customers sell our products to qualified healthcare professionals, is charged back to us by our customers. In addition to actual chargebacks received, we maintain a reserve for chargebacks based on estimated contractual discounts on product inventory levels on-hand in our distribution channel. To date, actual chargebacks have not differed materially from our estimates. Payor and Pharmacy Rebates. We are obligated to pay rebates as a percentage of sales under payor and pharmacy contracts. We estimate these rebates based on actual historical rebates, contractual rebate percentages, sales made through the payor channel and purchases made by pharmacies. To date, actual payor and pharmacy rebates have not differed materially from our estimates. Co-payment Assistance. We offer financial assistance to qualified patients with prescription drug co-payments required by insurance. We accrue for copay assistance based on estimated claims and the cost per claim we expect to receive associated with inventory that remains in the distribution channel at period end. To date, actual copay assistance has not differed materially from our estimates. Distributor and Other Fees. In connection with the sales of our products, we pay distributor and other fees to certain customers that provide us with inventory management, data and distribution services, which are generally recorded as a reduction of revenue. To the extent we can demonstrate a separable benefit and fair value for these services, we classify the associated costs in selling, general and administrative expenses. These costs are typically known at the time of sale, resulting in minimal adjustments subsequent to the period of sale. Product Returns. For INGREZZA, we offer our customers product return rights primarily limited to errors in shipment and damaged product. We do not permit returns of INGREZZA for expiring or expired product. Accordingly, we have limited return risk resulting from INGREZZA product sales and therefore do not record an associated returns allowance. For ONGENTYS, we offer our customers product return rights primarily limited to errors in shipment, damaged product, and expiring or expired product, provided it is within a specified period around the product expiration date, as set forth in the associated distribution agreement. Once product is returned, it is destroyed. Where actual returns history is not available, we estimate the associated returns allowance based on benchmarking data for similar products and industry experience. We record this estimate as a reduction of revenue in the period the related sale is recognized. To date, actual product returns have not differed materially from our estimates. Collaboration Revenues. We have entered into collaboration and licensing agreements under which we license certain rights to our product candidates to third parties. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; development, regulatory, and/or commercial milestone payments; and royalties on net sales of licensed products. Licenses of Intellectual Property. If the license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we use judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments. At the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, we evaluate whether achieving the milestones is considered probable and estimate the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone is included in the transaction price. Milestone payments that are not within our control, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer. Royalty Revenues. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Each quarterly period, sales-based royalties are recorded based on estimated quarterly net sales of the associated collaboration products. Differences between actual results and estimated amounts are adjusted for in the period in which they become known, which typically follows the quarterly period in which the estimate was made. To date, actual royalties received have not differed materially from our estimates.
Concentration of Credit Risk	Concentration of Credit Risk. Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash, cash equivalents and marketable securities. We have established guidelines to limit our exposure to credit risk by diversifying our investment portfolio and by placing investments with high credit quality financial institutions and maturities that maintain safety and liquidity. To date, we have not experienced any credit losses and do not believe we are exposed to any significant credit risk in relation to these financial instruments. We are also subject to credit risk from our accounts receivable related to our product sales. Our two largest customers represented approximately 86% of our product revenues for both 2020 and 2019, and the significant majority of our accounts receivable balances at December 31, 2020 and 2019. For 2018, our three largest customers represented approximately 93% of our product revenue and substantially all of our accounts receivable balance at December 31, 2018. To date, we have not experienced any significant losses with respect to the collection of these accounts receivable.
Cost of Sales	Cost of Sales. Cost of sales includes third-party manufacturing, transportation, freight and indirect overhead costs associated with the manufacture and distribution of INGREZZA and ONGENTYS, royalty fees on net sales of ORILISSA and ORIAHNN, and adjustments for excess and obsolete inventory to the extent management determines that the cost cannot be recovered based on estimates about future demand.
Research and Development Expenses	Research and Development Expenses. R&D expenses consist primarily of salaries, payroll taxes, employee benefits and share-based compensation charges for those individuals involved in ongoing R&D efforts; as well as scientific consulting fees, preclinical and clinical trial costs, R&D facilities costs, laboratory supply costs and depreciation of scientific equipment. All such costs are charged to R&D expense as incurred. These expenses result from our independent R&D efforts, as well as efforts associated with collaborations, in-licenses and third-party funded research arrangements, including event based milestones.
Asset Acquisitions	Asset Acquisitions. We account for acquisitions of an asset or group of assets that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the assets acquired on the basis of their relative fair values. No goodwill is recognized in an asset acquisition. Intangible assets that are acquired in an asset acquisition for use in R&D activities which have no alternative future use are expensed as in-process research and development, or IPR&D, on the acquisition date. Future costs to develop these assets are recorded to R&D expense as they are incurred.
Advertising Expense	Advertising Expense. Advertising costs are expensed when services are performed, or goods are delivered. We incurred advertising costs related to INGREZZA and ONGENTYS of $64.8 million for 2020, $40.6 million for 2019 and $20.5 million for 2018.
Share-Based Compensation	Share-Based Compensation. We grant stock options to purchase our common stock to eligible employees and directors and also grant certain employees restricted stock units, or RSUs, and performance-based restricted stock units, or PRSUs. Additionally, we allow employees to participate in an employee stock purchase plan, or ESPP. We estimate the fair value of stock options and shares to be issued under the ESPP using the Black-Scholes option-pricing model on the date of grant. Restricted stock units are valued based on the closing price of our common stock on the date of grant. The fair value of equity instruments expected to vest are recognized and amortized on a straight-line basis over the requisite service period of the award, which is generally three to four years; however, certain provisions in our equity compensation plans provide for shorter vesting periods under certain circumstances. The fair value of shares to be issued under the ESPP are recognized and amortized on a straight-line basis over the purchase period, which is generally six months. Additionally, we granted certain PRSUs that vest upon the achievement of certain predefined company-specific performance-based criteria. Expense related to these PRSUs is generally recognized ratably over the expected performance period once the predefined performance-based criteria for vesting becomes probable.
Income Taxes	Income Taxes. Our income tax benefit (provision) is computed under the asset and liability method. Significant estimates are required in determining our income tax benefit (provision). Some of these estimates are based on interpretations of existing tax laws or regulations. We recognize deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined on the basis of the difference between the tax basis of assets and liabilities and their respective financial reporting amounts (temporary differences) at enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is established for deferred tax assets for which it is more likely than not that some portion or all of the deferred tax assets, including net operating losses and tax credits, will not be realized. We periodically re-assess the need for a valuation allowance against our deferred tax assets based on various factors including our historical earnings experience by taxing jurisdiction, and forecasts of future operating results and utilization of net operating losses and tax credits prior to their expiration. Significant judgment is required in making this assessment and, to the extent that a reversal of any portion of our valuation allowance against our deferred tax assets is deemed appropriate, a tax benefit will be recognized against our income tax provision in the period of such reversal. Prior to 2020, we recorded a valuation allowance that fully offset our deferred tax assets. On December 31, 2020, based on our evaluation of various factors, such as our achievement of a cumulative three-year income position as of December 31, 2020, as well as our consideration of forecasts of future operating results and utilization of net operating losses and tax credits prior to their expiration, we released substantially all of our valuation allowance against our deferred tax assets and recorded a corresponding income tax benefit. Refer to Note 9 to the consolidated financial statements for more information. We recognize tax benefits from uncertain tax positions only if it is more likely than not that the tax position will be sustained upon examination by the tax authorities based on the technical merits of the position. An adverse resolution of one or more of these uncertain tax positions in any period could have a material impact on the results of operations for that period.
Net Income Per Share	Net Income Per Share. Basic net income per share is computed using the weighted average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common and potentially dilutive shares outstanding during the period, including the potentially dilutive shares resulting from the conversion of the 2024 Notes and excluding the effect of stock options and restricted stock outstanding for periods when their effect is anti-dilutive, using the treasury stock method. Convertible debt instruments that may be settled entirely or partly in cash (such as the 2024 Notes) may, in certain circumstances where the borrower has the ability and intent to settle in cash, be accounted for under the treasury stock method. We issued the 2024 Notes with a combination settlement feature, which we have the ability and intent to use upon conversion of the 2024 Notes, to settle the principal amount of debt for cash and the excess of the principal portion in shares of our common stock. As a result, of the approximately 5.0 million shares underlying the 2024 Notes at December 31, 2020, only the shares required to settle the excess of the principal portion would be considered dilutive under the treasury stock method. Further, approximately 0.2 million PRSUs were excluded from the calculation of diluted net income per share as the performance condition has not been achieved. In loss periods, basic net loss per share and diluted net loss per share are identical because the otherwise dilutive potential common shares become anti-dilutive and are therefore excluded.
Recently Adopted 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, 2020, including 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 ASU 2019-12 will have on our condensed consolidated financial statements and related disclosures. ASU 2020-06. In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments, and amends existing earnings-per-share, or EPS, guidance by requiring that an entity use the if-converted method when calculating diluted EPS for convertible instruments. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years, with early adoption permitted for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We plan to adopt ASU 2020-06 effective January 1, 2022 and are currently evaluating the effect ASU 2020-06 will have on our consolidated financial statements and related disclosures.

Debt Securities (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Amortized cost, gross unrealized gain (loss) positions and estimated fair value for available-for-sale debt securities


(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss		Allowance for Credit Losses		Fair Value
Commercial paper	Within 1 year	$	82.2	$	—	$	—	$	—	$	82.2
Corporate debt securities	Within 1 year	299.3		1.4		—		—		300.7
Securities of government-sponsored entities	Within 1 year	230.9		0.1		—		—		231.0
		$	612.4	$	1.5	$	—	$	—	$	613.9

Corporate debt securities	1 to 2 years	$	144.8	$	0.4	$	—	$	—	$	145.2
Securities of government-sponsored entities	1 to 2 years	81.9		0.1		(0.1)		—		81.9
		$	226.7	$	0.5	$	(0.1)	$	—	$	227.1


(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
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


	Less Than 12 Months				12 Months or Longer				Total
(in millions)	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Securities of government-sponsored entities	$	95.0	$	(0.1)	$	—	$	—	$	95.0	$	(0.1)


	Less Than 12 Months				12 Months or Longer				Total
(in millions)	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate debt securities	$	186.1	$	(0.1)	$	—	$	—	$	186.1	$	(0.1)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Investments measured at fair value on recurring basis

Investments at December 31, 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	$	187.1	$	187.1	$	—	$	—
Total cash and cash equivalents	187.1		187.1		—		—
Restricted cash:
Certificates of deposit	3.2		3.2		—		—
Total restricted cash	3.2		3.2		—		—
Debt securities available-for-sale:
Commercial paper	82.2		—		82.2		—
Corporate debt securities	445.9		—		445.9		—
Securities of government-sponsored entities	312.9		—		312.9		—
Total debt securities available-for-sale	841.0		—		841.0		—
Equity securities:
Equity securities–biotechnology industry	38.2		—		—		38.2
Total equity securities	38.2		—		—		38.2
Total recurring fair value measurements	$	1,069.5	$	190.3	$	841.0	$	38.2

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 equity securities measured at fair value on recurring basis using significant unobservable inputs

The following table presents a reconciliation of equity securities, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3):


	Year Ended December 31,
(in millions)	2020		2019		2018
Beginning balance	$	55.9	$	—	$	—
Purchases	—		68.9		—
Unrealized loss included in earnings	(17.7)		(13.0)		—
Ending balance	$	38.2	$	55.9	$	—

Convertible Senior Notes (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Convertible senior notes net of discounts and deferred financing costs

The 2024 Notes, net of discounts and deferred financing costs, consisted of the following:


	December 31,
(in millions)	2020		2019
Principal	$	381.3	$	517.5
Deferred financing costs	(4.0)		(6.9)
Debt discount, net	(59.4)		(101.8)
Net carrying amount	$	317.9	$	408.8

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Other Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2020

Other Balance Sheet Details [Abstract]

Inventories

Inventories consisted of the following:


	December 31,
(in millions)	2020		2019
Raw materials	$	16.6	$	14.1
Work in process	2.4		1.5
Finished goods	9.0		1.7
Total inventories	$	28.0	$	17.3

Property and Equipment

Property and equipment, net, consisted of the following:


	December 31,
(in millions)	2020		2019
Tenant improvements	$	29.5	$	26.3
Scientific equipment	39.2		33.5
Computer equipment	13.9		12.5
Furniture and fixtures	3.7		3.2
	86.3		75.5
Less accumulated depreciation	(41.7)		(33.6)
Total property and equipment, net	$	44.6	$	41.9

Accounts Payable and Accrued Liabilities

Accounts payable and accrued liabilities consisted of the following:


	December 31,
(in millions)	2020		2019
Accrued employee related costs	$	38.2	$	38.9
Revenue-related reserves for discounts and allowances	34.6		30.6
Accrued development costs	32.9		25.5
Accrued Branded Prescription Drug Fee	23.6		4.9
Accounts payable and other accrued liabilities	39.4		41.4
Total accounts payable and accrued liabilities	$	168.7	$	141.3

Reconciliation of Cash, Cash Equivalents and Restricted Cash


	December 31,
(in millions)	2020		2019
Cash and cash equivalents	$	187.1	$	112.3
Restricted cash	3.2		3.2
Total cash, cash equivalents and restricted cash	$	190.3	$	115.5

Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of net income (loss) per share

Net income per share was calculated as follows:


	Year Ended December 31,
(in millions, except per share data)	2020		2019		2018
Net income - basic and diluted	$	407.3	$	37.0	$	21.1
Weighted-average common shares outstanding:
Basic	93.1		91.6		90.2
Effect of dilutive securities:

Stock options	2.4		2.6		3.2
Restricted stock units	0.5		0.4		0.6
2024 Notes	1.8		1.1		1.3
Diluted	97.8		95.7		95.4
Net income per share:
Basic	$	4.38	$	0.40	$	0.23
Diluted	$	4.16	$	0.39	$	0.22

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Compensation cost related to share based compensation

The effect of share-based compensation expense on our consolidated statements of income and comprehensive income by line-item follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Selling, general and administrative expense	$	66.3	$	49.5	$	31.9
Research and development expense	33.7		25.8		26.2
Total share-based compensation expense	$	100.0	$	75.3	$	58.1

Share-based compensation expense by award-type follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Stock options	$	47.5	$	36.5	$	35.4
RSUs	44.2		30.5		21.9
PRSUs	5.3		5.6		—
ESPP	3.0		2.7		0.8
Total share-based compensation expense	$	100.0	$	75.3	$	58.1

At December 31, 2020, unrecognized share-based compensation expense by award-type and the weighted-average period over which such expense is expected to be recognized, as applicable, were as follows:


(dollars in millions)	Unrecognized Expense		Weighted-Average Recognition Period
Stock options	$	86.2	2.3 years
RSUs	$	99.5	2.3 years

Weighted-average assumptions for stock option grants using black-scholes option-pricing model

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


	Year Ended December 31,
	2020		2019		2018
Risk-free interest rate	1.4	%	2.4	%	2.5	%
Expected volatility of common stock	48.5	%	54.8	%	59.5	%
Dividend yield	0.0	%	0.0	%	0.0	%
Expected option term	5.3 years		5.4 years		4.7 years

Summary and changes in stock options outstanding

A summary of activity related to stock options follows:


(in millions, except weighted average data)	Number of Stock Options	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2019	6.1	$	52.62
Granted	1.3	$	103.44
Exercised	(0.6)	$	43.90
Canceled	—	$	—
Outstanding at December 31, 2020	6.8	$	62.98	6.4 years	$	235.4
Exercisable at December 31, 2020	4.7	$	49.80	5.5 years	$	218.2

Summary and changes in restricted stock units outstanding

A summary of activity related to RSUs follows:


(in millions, except weighted average data)	Number of RSUs	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Unvested at December 31, 2019	1.4	$	74.77
Granted	0.7	$	102.92
Released	(0.5)	$	67.86
Canceled	(0.1)	$	84.95
Unvested at December 31, 2020	1.5	$	89.60	1.3 years	$	147.5

A summary of activity related to PRSUs follows:


(in millions, except weighted average data)	Number of PRSUs	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Unvested at December 31, 2019	0.3	$	59.62
Granted	0.2	$	102.90
Released	(0.1)	$	82.04
Canceled	(0.2)	$	45.67
Unvested at December 31, 2020	0.2	$	102.90	2.2 years	$	15.8

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Components of income tax expense for continuing operations

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


	Year Ended December 31,
(in millions)	2020		2019		2018
Current:
Federal	$	—	$	—	$	(0.1)
State	10.1		9.5		0.8
Total current taxes	10.1		9.5		0.7
Deferred:
Federal	(287.5)		—		—
State	(23.2)		—		—
Total deferred taxes	(310.7)		—		—
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7

Provision for income taxes on earnings subject to income taxes differs from statutory federal rate

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


	Year Ended December 31,
(in millions)	2020		2019		2018
Federal income taxes at 21% for 2020, 2019, 2018	$	22.4	$	9.8	$	4.6
State income tax, net of federal benefit	5.5		4.0		0.4
Non-deductible expenses	0.6		0.8		0.4
Branded prescription drug fee	4.9		3.7		—
Share-based compensation expense	(6.7)		(12.8)		(9.8)
Officer compensation	3.7		3.1		0.9
Change in tax rate	3.3		(4.1)		(0.2)
Expired tax attributes	1.1		1.2		13.9
Research credits	(39.0)		(10.4)		(13.5)
Change in valuation allowance	(296.3)		13.9		4.3
Other	(0.1)		0.3		(0.3)
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7

Components of deferred tax assets

Significant components of our deferred tax assets as of December 31, 2020 and 2019 are listed below.


	December 31,
(in millions)	2020		2019
Deferred tax assets:
Net operating losses	$	111.4	$	181.3
Research and development credits	109.6		71.9
Capitalized research and development	24.7		28.0
Share-based compensation expense	29.8		22.9
Operating lease assets	25.2		23.3
Intangible assets	86.7		49.3
Other	23.9		18.5
Total deferred tax assets	411.3		395.2
Deferred tax liabilities:
Convertible senior notes	(13.8)		(24.1)
Operating lease liabilities	(19.9)		(18.2)
Other	(8.4)		(6.9)
Total deferred tax liabilities	(42.1)		(49.2)
Net of deferred tax assets and liabilities	369.2		346.0
Valuation allowance	(49.8)		(346.0)
Net deferred tax assets	$	319.4	$	—

A summary of activity related to unrecognized tax benefits follows:


	Year Ended December 31,
(in millions)	2020		2019		2018
Balance at January 1	$	63.9	$	54.8	$	37.4
(Decrease) increase related to prior year tax positions	(5.7)		0.3		6.1
Increase related to current year tax positions	3.9		9.5		11.7
Settlements related to prior year tax positions	(0.2)		—		—
Expiration of the statute of limitations for the assessment of taxes	(1.1)		(0.7)		(0.4)
Balance at December 31	$	60.8	$	63.9	$	54.8

Leases (Table)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Summary of minimum lease payments for operating lease liabilities

Approximate future minimum lease payments under operating leases were as follows:


(in millions)	December 31, 2020
Year ending December 31, 2021	$	10.7
Year ending December 31, 2022	12.4
Year ending December 31, 2023	12.7
Year ending December 31, 2024	13.1
Year ending December 31, 2025	13.5
Thereafter	77.5
Total operating lease payments	139.9
Less accreted interest	35.2
Total operating lease liabilities	104.7
Less current operating lease liabilities	10.3
Noncurrent operating lease liabilities	$	94.4

Note 1: Amounts presented in the table above exclude $19.7 million of non-cancelable future minimum lease payments for operating leases that have not yet commenced.

Note 2: Current operating lease liabilities are included in other current liabilities on the consolidated balance sheets.

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Results of Operations

A summary of our quarterly results follows:


(in millions, except per share data)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
Year Ended December 31, 2020:
Total revenues	$	237.1	$	302.4	$	258.5	$	247.9
Total operating expenses (1)	$	178.2	$	225.8	$	302.8	$	176.1
Net income (loss) (1)	$	37.4	$	79.6	$	(57.6)	$	347.9
Net income (loss) per share, basic (1)	$	0.40	$	0.86	$	(0.62)	$	3.72
Net income (loss) per share, diluted (1)	$	0.39	$	0.81	$	(0.62)	$	3.58
Weighted average common shares outstanding, basic	92.6		93.0		93.3		93.5
Weighted average common shares outstanding, diluted	97.0		98.2		93.3		97.2

Year Ended December 31, 2019:
Total revenues	$	138.4	$	183.5	$	222.1	$	244.1
Total operating expenses (2)	$	239.4	$	149.1	$	132.0	$	195.3
Net (loss) income (2)	$	(102.1)	$	51.3	$	53.8	$	34.0
Net (loss) income per share, basic (2)	$	(1.12)	$	0.56	$	0.59	$	0.37
Net (loss) income per share, diluted (2)	$	(1.12)	$	0.54	$	0.56	$	0.35
Weighted average common shares outstanding, basic	91.1		91.4		91.9		92.2
Weighted average common shares outstanding, diluted	91.1		94.8		96.1		97.2

Organization and Summary of Significant Accounting Policies - Additional Information (Details) shares in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($) subsidiary segment shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of wholly owned Irish subsidiaries \| subsidiary		2
Number of operating segments \| segment		1
Number of reportable segments \| segment		1
Accrued interest receivables write-off threshold period	90 days	90 days
Accrued interest receivables	$ 3,700,000	$ 3,700,000
Accrued interest receivables write-off		0	$ 0	$ 0
Depreciation		8,600,000	7,400,000	4,000,000.0
Advertising expense		$ 64,800,000	$ 40,600,000	$ 20,500,000
PRSUs
Organization And Summary Of Significant Accounting Policies [Line Items]
Ending Balance, Unvested (in shares) \| shares	0.2	0.2	0.3
2.25% Convertible senior notes due 2024
Organization And Summary Of Significant Accounting Policies [Line Items]
Shares issued to settle notes at initial conversion rate (in shares) \| shares	5.0
ESPP
Organization And Summary Of Significant Accounting Policies [Line Items]
Share based compensation arrangement by share based payment award purchase period		6 months
Revenue, Product and Service Benchmark \| Customer Concentration Risk \| Largest two customers
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		86.00%	86.00%
Revenue, Product and Service Benchmark \| Customer Concentration Risk \| Largest three customers
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				93.00%
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		3 years
Share-based compensation arrangement by share-based payment award, award requisite service period		3 years
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		7 years
Share-based compensation arrangement by share-based payment award, award requisite service period		4 years

License and Collaboration Agreements - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended			3 Months Ended								12 Months Ended			28 Months Ended	42 Months Ended	126 Months Ended
	May 31, 2020	Mar. 31, 2015	Jun. 30, 2010	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2017	Dec. 31, 2020	Dec. 31, 2020	Jul. 31, 2020	Apr. 30, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				$ 8,500.0								$ 8,500.0				$ 8,500.0	$ 8,500.0
Equity securities fair value amount				38.2				$ 55.9				38.2	$ 55.9			38.2	38.2
Acquired in-process research and development												164.5	154.3	$ 4.8
Revenues				247.9	$ 258.5	$ 302.4	$ 237.1	244.1	$ 222.1	$ 183.5	$ 138.4	1,045.9	788.1	451.2
Takeda \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				1,900.0								1,900.0				1,900.0	1,900.0
Upfront payments made																		$ 120.0
Acquired in-process research and development					$ 118.5
Idorsia \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payments made	$ 45.0
Incremental funding provided	$ 7.2
Research collaboration term	2 years
Potential commercial milestone payments				750.0								750.0				750.0	750.0
Acquired in-process research and development						46.0
Idorsia \| Collaborative Arrangement \| NBI-827104
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				365.0								365.0				365.0	365.0
Idorsia \| Collaborative Arrangement \| Development Product Candidates
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				620.0								620.0				620.0	620.0
Xenon \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				1,700.0								1,700.0				1,700.0	1,700.0
Upfront payments made								30.0					30.0
Investment in equity securities without readily determinable fair value								$ 20.0					$ 20.0
Share price (in USD per share)								$ 14.196					$ 14.196
Equity securities fair value amount								$ 14.1					$ 14.1
Acquired in-process research and development								$ 36.2
Xenon \| Collaborative Arrangement \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity securities number of shares (in shares)								1.4					1.4
Voyager \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				1,700.0								1,700.0				1,700.0	1,700.0
Upfront payments made											115.0
Investment in equity securities without readily determinable fair value											$ 50.0
Share price (in USD per share)											$ 11.9625
Equity securities fair value amount											$ 54.7
Acquired in-process research and development										$ 5.0	$ 113.1
Voyager \| Collaborative Arrangement \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity securities number of shares (in shares)											4.2
B I A L \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments				75.0								75.0				75.0	75.0
Milestone payments								$ 10.0					$ 10.0	10.0					$ 20.0
Mitsubishi Tanabe \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues															$ 19.8	15.0
Deferred revenue recognized												2.7	0.9
Contract with customer, liability				6.7								6.7				6.7	6.7
Upfront payments received		$ 30.0
Potential milestone payment receipts				70.0								70.0				70.0	70.0
Mitsubishi Tanabe \| Collaborative Arrangement \| Patents \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Patent term		10 years
AbbVie \| Royalty
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues												19.2	14.3	1.6
AbbVie \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues			$ 75.0			$ 30.0							$ 20.0	$ 40.0			165.0
Potential milestone payment receipts				$ 366.0								$ 366.0				$ 366.0	$ 366.0
AbbVie \| Collaborative Arrangement \| Patents \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Patent term			10 years

Debt Securities - Amortized Cost, Gross Unrealized Gain (Loss) Positions and Estimated Fair Value for Available-For-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 612.4	$ 557.3
Unrealized Gain	1.5	0.9
Unrealized Loss	0.0	0.0
Allowance for Credit Losses	0.0
Fair Value	613.9	558.2
Short-term investments \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	299.3	270.5
Unrealized Gain	1.4	0.5
Unrealized Loss	0.0	0.0
Allowance for Credit Losses	0.0
Fair Value	300.7	271.0
Short-term investments \| Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	230.9	142.3
Unrealized Gain	0.1	0.4
Unrealized Loss	0.0	0.0
Allowance for Credit Losses	0.0
Fair Value	231.0	142.7
Short-term investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	82.2	144.5
Unrealized Gain	0.0	0.0
Unrealized Loss	0.0	0.0
Allowance for Credit Losses	0.0
Fair Value	82.2	144.5
Long-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	226.7	299.3
Unrealized Gain	0.5	0.5
Unrealized Loss	(0.1)	(0.1)
Allowance for Credit Losses	0.0
Fair Value	227.1	299.7
Long-term investments \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	144.8	250.5
Unrealized Gain	0.4	0.5
Unrealized Loss	0.0	(0.1)
Allowance for Credit Losses	0.0
Fair Value	145.2	250.9
Long-term investments \| Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	81.9	48.8
Unrealized Gain	0.1	0.0
Unrealized Loss	(0.1)	0.0
Allowance for Credit Losses	0.0
Fair Value	$ 81.9	$ 48.8

Debt Securities - Gross Unrealized Losses and Fair Value Available-For-Sale Debt securities in Unrealized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 95.0
Less Than 12 Months, Unrealized Losses	(0.1)
12 Months or Longer, Fair Value	0.0
12 Months or Longer, Unrealized Losses	0.0
Total Fair Value	95.0
Total Unrealized Losses	$ (0.1)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value		$ 186.1
Less Than 12 Months, Unrealized Losses		(0.1)
12 Months or Longer, Fair Value		0.0
12 Months or Longer, Unrealized Losses		0.0
Total Fair Value		186.1
Total Unrealized Losses		$ (0.1)

Debt Securities - Additional Information (Details)	Dec. 31, 2020 security
Investments, Debt and Equity Securities [Abstract]
Debt securities available for sale position number of positions	148
Number of debt securities available-for-sale in an unrealized loss position	30

Fair Value Measurements - Reconciliation of Equity Securities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, beginning balance	$ 55.9
Purchases	0.0	$ 68.9	$ 0.0
Unrealized loss included in earnings	(17.7)	(13.0)	0.0
Equity securities, ending balance	38.2	55.9
Fair value measurements recurring \| Equity securities–biotechnology industry \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, beginning balance	55.9	0.0	0.0
Purchases	0.0	68.9	0.0
Unrealized loss included in earnings	(17.7)	(13.0)	0.0
Equity securities, ending balance	$ 38.2	$ 55.9	$ 0.0

Fair Value Measurements - Additional Information (Details) - Measurement input, discount for lack of marketability	Dec. 31, 2020
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities, FV-NI, measurement input	0.150
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities, FV-NI, measurement input	0.340
Weighted average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities, FV-NI, measurement input	0.248

Convertible Senior Notes - Additional Information (Details) $ / shares in Units, shares in Millions		1 Months Ended		12 Months Ended
	May 02, 2017 USD ($) d $ / shares	Dec. 31, 2020 USD ($) shares	Nov. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Principal amount		$ 381,300,000		$ 381,300,000	$ 517,500,000
Equity component of repurchased convertible senior notes				47,500,000
Loss on extinguishment of convertible senior notes				$ 18,400,000	0	$ 0
2.25% Convertible senior notes due 2024
Debt Instrument [Line Items]
Principal amount	$ 517,500,000
Stated 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%
Principal amount on conversion rate	$ 1,000
Trading days during observation period	30 days
Conversion observation period	25 days
Conversion ratio	0.00131711
Conversion price (in USD per share) \| $ / shares	$ 75.92
Shares issued to settle notes at initial conversion rate (in shares) \| shares		5.0
Conversion premium	42.50%
Market price of common stock (in USD per share) \| $ / shares	$ 53.28
Redemption rate	100.00%
Carrying amount of the liability component upon issuance	$ 368,300,000
Assumed borrowing rate	7.50%
Carrying amount of the equity component upon issuance	$ 149,200,000
Term	7 years
Remaining discount amortization period				3 years 4 months 24 days
Transaction cost related to issuance of convertible senior note	$ 14,700,000
Events of default percentage of principal and accrued and unpaid interest due and payable upon default	100.00%
Aggregate principal amount repurchased			$ 136,200,000
Aggregate repurchase price paid in cash			186,900,000
Fair value of the liability component immediately before extinguishment			130,700,000
Equity component of repurchased convertible senior notes			56,300,000
Carrying amount of the liability component at settlement			112,400,000
Loss on extinguishment of convertible senior notes			$ 18,400,000
Fair value		$ 514,300,000		$ 514,300,000	$ 596,800,000
2.25% Convertible senior notes due 2024 \| Conversion Period One
Debt Instrument [Line Items]
Threshold common stock trading days \| d	20
Threshold consecutive common stock trading days \| d	30
Threshold percentage of common stock price trigger	130.00%
2.25% Convertible senior notes due 2024 \| Conversion Period Two
Debt Instrument [Line Items]
Threshold common stock trading days \| d	5
Threshold consecutive common stock trading days \| d	5
Principal amount on conversion rate	$ 1,000
Minimum percentage of common stock price trigger	98.00%
2.25% Convertible senior notes due 2024 \| Discount rate
Debt Instrument [Line Items]
Discount rate			0.0337

Convertible Senior Notes, Net of Discounts and Deferred Financing Costs (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Principal	$ 381.3	$ 517.5
Deferred financing costs	(4.0)	(6.9)
Debt discount, net	(59.4)	(101.8)
Net carrying amount	$ 317.9	$ 408.8

Other Balance Sheet Details - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Balance Sheet Details [Abstract]
Raw materials	$ 16.6	$ 14.1
Work in process	2.4	1.5
Finished goods	9.0	1.7
Total inventories	$ 28.0	$ 17.3

Other Balance Sheet Details - Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment	$ 86.3	$ 75.5
Less accumulated depreciation	(41.7)	(33.6)
Total property and equipment, net	44.6	41.9
Tenant improvements
Property, Plant and Equipment [Line Items]
Property and equipment	29.5	26.3
Scientific equipment
Property, Plant and Equipment [Line Items]
Property and equipment	39.2	33.5
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	13.9	12.5
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	$ 3.7	$ 3.2

Other Balance Sheet Details - Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Balance Sheet Details [Abstract]
Accrued employee related costs	$ 38.2	$ 38.9
Revenue-related reserves for discounts and allowances	34.6	30.6
Accrued development costs	32.9	25.5
Accrued Branded Prescription Drug Fee	23.6	4.9
Accounts payable and other accrued liabilities	39.4	41.4
Total accounts payable and accrued liabilities	$ 168.7	$ 141.3

Other Balance Sheet Details - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Balance Sheet Details [Abstract]
Cash and cash equivalents	$ 187.1	$ 112.3
Restricted cash	3.2	3.2
Total cash, cash equivalents and restricted cash	$ 190.3	$ 115.5

Net Income Per Share - Schedule of Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items]
Net income (loss)	$ 347.9	$ (57.6)	$ 79.6	$ 37.4	$ 34.0	$ 53.8	$ 51.3	$ (102.1)	$ 407.3	$ 37.0	$ 21.1
Weighted-average common shares outstanding:
Basic (in shares)	93.5	93.3	93.0	92.6	92.2	91.9	91.4	91.1	93.1	91.6	90.2
Effect of dilutive securities:
Diluted (in shares)	97.2	93.3	98.2	97.0	97.2	96.1	94.8	91.1	97.8	95.7	95.4
Net income per share:
Basic (in USD per share)	$ 3.72	$ (0.62)	$ 0.86	$ 0.40	$ 0.37	$ 0.59	$ 0.56	$ (1.12)	$ 4.38	$ 0.40	$ 0.23
Diluted (in USD per share)	$ 3.58	$ (0.62)	$ 0.81	$ 0.39	$ 0.35	$ 0.56	$ 0.54	$ (1.12)	$ 4.16	$ 0.39	$ 0.22
2.25% Convertible Senior Notes
Effect of dilutive securities:
2024 Notes (in shares)									1.8	1.1	1.3
Stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)									2.4	2.6	3.2
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (in shares)									0.5	0.4	0.6

Net Income Per Share - Schedule of Anti-Dilutive Shares Excluded from Diluted Per Share Amounts (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock options restricted stock and convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from diluted per share amounts (in shares)	2.5	2.1	0.9

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 31, 2020	May 31, 2018	May 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair values of stock options granted (in USD per share)	$ 45.67	$ 41.74	$ 43.42
Stock options exercised in period intrinsic value	$ 40.2	$ 64.3	$ 117.0
Cash received from stock option exercises	$ 23.5	27.3	29.5
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock authorized for issuance (in shares)	200,000				300,000
ESPP \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discounted purchase price percentage of common stock authorized for issuance	85.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of stock options	10 years
Unrecognized expense	$ 86.2
Stock options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Total intrinsic value vested in period	$ 49.7	$ 36.1	$ 35.5
Unrecognized expense	99.5
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense	17.0
Total fair value of PRSUs vested	$ 13.5
PRSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
PRSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock authorized for issuance (in shares)	0					21,000,000
2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock authorized for issuance (in shares)	8,200,000			3,300,000

Share-Based Compensation - Compensation Cost Related to Share-Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 100.0	$ 75.3	$ 58.1
Selling, general and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	66.3	49.5	31.9
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 33.7	$ 25.8	$ 26.2

Share-Based Compensation - Schedule of Share-based Compensation Expense by Award-type (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 100,000,000.0	$ 75,300,000	$ 58,100,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	47,500,000	36,500,000	35,400,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	44,200,000	30,500,000	21,900,000
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	5,300,000	5,600,000	0
ESPP
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 3,000,000.0	$ 2,700,000	$ 800,000

Share-Based Compensation - Schedule of Share-based Compensation Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Unrecognized Expense	$ 86.2
Weighted-Average Recognition Period	2 years 3 months 18 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Unrecognized Expense	$ 99.5
Weighted-Average Recognition Period	2 years 3 months 18 days

Share-Based Compensation - Weighted-Average Assumptions for Stock Option Grants using Black-Scholes Option-Pricing Model (Details) - Stock options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.40%	2.40%	2.50%
Expected volatility of common stock	48.50%	54.80%	59.50%
Dividend yield	0.00%	0.00%	0.00%
Expected option term	5 years 3 months 18 days	5 years 4 months 24 days	4 years 8 months 12 days

Share-Based Compensation - Summary of Activity Related to Stock Options (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Number of Stock Options
Beginning Balance, Outstanding (in shares) \| shares	6,100
Granted (in shares) \| shares	1,300
Exercised (in shares) \| shares	(600)
Canceled (in shares) \| shares	0
Ending Balance, Outstanding (in shares) \| shares	6,800
Exercisable (in shares) \| shares	4,700
Weighted Average Exercise Price
Beginning Balance, Outstanding (in USD per share) \| $ / shares	$ 52.62
Granted (in USD per share) \| $ / shares	103.44
Exercised (in USD per share) \| $ / shares	43.90
Canceled (in USD per share) \| $ / shares	0
Ending Balance, Outstanding (in USD per share) \| $ / shares	62.98
Exercisable (in USD per share) \| $ / shares	$ 49.80
Weighted-Average Remaining Contractual Life and Aggregate Intrinsic Value
Weighted-Average Remaining Contractual Term, Outstanding	6 years 4 months 24 days
Weighted-Average Remaining Contractual Term, Exercisable	5 years 6 months
Aggregate Intrinsic Value, Outstanding \| $	$ 235.4
Aggregate Intrinsic Value, Exercisable \| $	$ 218.2

Share-Based Compensation - Summary and Changes in Restricted Stock Units Outstanding (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
RSUs
Number of Units
Beginning Balance, Unvested (in shares)	1,400,000
Granted (in shares)	700,000
Released (in shares)	(500,000)
Canceled (in shares)	(100,000)
Ending Balance, Unvested (in shares)	1,500,000	1,400,000
Weighted-Average Grant Date Fair Value
Beginning Balance, Unvested (in USD per share)	$ 74.77
Granted (in USD per share)	102.92
Released (in USD per share)	67.86
Canceled (in USD per share)	84.95
Ending Balance, Unvested (in USD per share)	$ 89.60	$ 74.77
Weighted-Average Remaining Contractual Life and Aggregate Intrinsic Value
Unvested, weighted average remaining contractual term (in years)	1 year 3 months 18 days
Unvested, aggregate intrinsic value	$ 147.5
PRSUs
Number of Units
Beginning Balance, Unvested (in shares)	300,000
Granted (in shares)	200,000
Released (in shares)	(100,000)	0	0
Canceled (in shares)	(200,000)
Ending Balance, Unvested (in shares)	200,000	300,000
Weighted-Average Grant Date Fair Value
Beginning Balance, Unvested (in USD per share)	$ 59.62
Granted (in USD per share)	102.90
Released (in USD per share)	82.04
Canceled (in USD per share)	45.67
Ending Balance, Unvested (in USD per share)	$ 102.90	$ 59.62
Weighted-Average Remaining Contractual Life and Aggregate Intrinsic Value
Unvested, weighted average remaining contractual term (in years)	2 years 2 months 12 days
Unvested, aggregate intrinsic value	$ 15.8

Income Taxes - Components of Income Tax Expense for Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0.0	$ 0.0	$ (0.1)
State	10.1	9.5	0.8
Total current taxes	10.1	9.5	0.7
Deferred:
Federal	(287.5)	0.0	0.0
State	(23.2)	0.0	0.0
Total deferred taxes	(310.7)	0.0	0.0
(Benefit from) provision for income taxes	$ (300.6)	$ 9.5	$ 0.7

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal income taxes, rate	21.00%	21.00%	21.00%
Federal income taxes at 21% for 2020, 2019, 2018	$ 22.4	$ 9.8	$ 4.6
State income tax, net of federal benefit	5.5	4.0	0.4
Non-deductible expenses	0.6	0.8	0.4
Branded prescription drug fee	4.9	3.7	0.0
Share-based compensation expense	(6.7)	(12.8)	(9.8)
Officer compensation	3.7	3.1	0.9
Change in tax rate	3.3	(4.1)	(0.2)
Expired tax attributes	1.1	1.2	13.9
Research credits	(39.0)	(10.4)	(13.5)
Change in valuation allowance	(296.3)	13.9	4.3
Other	(0.1)	0.3	(0.3)
(Benefit from) provision for income taxes	$ (300.6)	$ 9.5	$ 0.7

Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating losses	$ 111.4	$ 181.3
Research and development credits	109.6	71.9
Capitalized research and development	24.7	28.0
Share-based compensation expense	29.8	22.9
Operating lease assets	25.2	23.3
Intangible assets	86.7	49.3
Other	23.9	18.5
Total deferred tax assets	411.3	395.2
Deferred tax liabilities:
Convertible senior notes	(13.8)	(24.1)
Operating lease liabilities	(19.9)	(18.2)
Other	(8.4)	(6.9)
Total deferred tax liabilities	(42.1)	(49.2)
Net of deferred tax assets and liabilities	369.2	346.0
Valuation allowance	(49.8)	(346.0)
Net deferred tax assets	$ 319.4	$ 0.0

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Deferred tax assets, valuation allowance	$ 49.8	$ 346.0
Realizable deferred tax assets	319.4
Deferred tax assets, net valuation release	296.3
Research and development tax credit carry forwards	109.6	71.9
Increase related to current year tax positions	3.9	$ 9.5	$ 11.7
Unrecognized tax benefits that would affect effective tax rate	53.9
Federal
Income Taxes [Line Items]
Operating loss carry forward, net	518.2
Research and development tax credit carry forwards	92.1
State and local jurisdiction
Income Taxes [Line Items]
Operating loss carry forward, net	340.8
Research and development tax credit carry forwards	$ 56.4

Income Taxes - Summary of Activity Related to Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Balance at January 1	$ 63.9	$ 54.8	$ 37.4
(Decrease) related to prior year tax positions	(5.7)
Increase related to prior year tax positions		0.3	6.1
Increase related to current year tax positions	3.9	9.5	11.7
Settlements related to prior year tax positions	(0.2)	0.0	0.0
Expiration of the statute of limitations for the assessment of taxes	(1.1)	(0.7)	(0.4)
Balance at December 31	$ 60.8	$ 63.9	$ 54.8

Leases - Additional Information (Details) $ in Millions	12 Months Ended
Leases - Additional Information (Details) $ in Millions	Dec. 31, 2020 USD ($) renewalOption	Dec. 31, 2019 USD ($)
Leases [Line Items]
Number of renewal options \| renewalOption	2
Renewal term	10 years
Restricted cash	$ 3.2	$ 3.2
Cost	10.1	8.1
Payments	$ 8.6	$ 7.7
Weighted average remaining term	10 years 3 months 18 days	11 years 2 months 12 days
Weighted average discount rate	5.60%	5.80%
Letter of Credit
Leases [Line Items]
Restricted cash	$ 3.2

Leases - Summary of Future Minimum Lease Payments Under Operating Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Year ending December 31, 2021	$ 10.7
Year ending December 31, 2022	12.4
Year ending December 31, 2023	12.7
Year ending December 31, 2024	13.1
Year ending December 31, 2025	13.5
Thereafter	77.5
Total operating lease payments	139.9
Less accreted interest	35.2
Total operating lease liabilities	104.7
Less current operating lease liabilities	10.3
Noncurrent operating lease liabilities	94.4	$ 86.7
Non-cancelable future minimum lease payments for operating leases that have not yet commenced	$ 19.7
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Defined contribution plan, maximum employee contribution percentage	60.00%
Defined contribution plan, employer contribution amount	$ 6.7	$ 4.9	$ 1.8

Summary of Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 247.9	$ 258.5	$ 302.4	$ 237.1	$ 244.1	$ 222.1	$ 183.5	$ 138.4	$ 1,045.9	$ 788.1	$ 451.2
Total operating expenses	176.1	302.8	225.8	178.2	195.3	132.0	149.1	239.4	882.9	715.8	414.4
Net income (loss)	$ 347.9	$ (57.6)	$ 79.6	$ 37.4	$ 34.0	$ 53.8	$ 51.3	$ (102.1)	$ 407.3	$ 37.0	$ 21.1
Net income (loss) per share, basic (in USD per share)	$ 3.72	$ (0.62)	$ 0.86	$ 0.40	$ 0.37	$ 0.59	$ 0.56	$ (1.12)	$ 4.38	$ 0.40	$ 0.23
Net income (loss) per share, diluted (in USD per share)	$ 3.58	$ (0.62)	$ 0.81	$ 0.39	$ 0.35	$ 0.56	$ 0.54	$ (1.12)	$ 4.16	$ 0.39	$ 0.22
Weighted average common shares outstanding, basic (in shares)	93.5	93.3	93.0	92.6	92.2	91.9	91.4	91.1	93.1	91.6	90.2
Weighted average common shares outstanding, diluted (in shares)	97.2	93.3	98.2	97.0	97.2	96.1	94.8	91.1	97.8	95.7	95.4

- Definition

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

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Summary of Quarterly Results of Operations - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development						$ 164.5	$ 154.3	$ 4.8
Idorsia \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development		$ 46.0
Takeda \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development	$ 118.5
Voyager \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development				$ 5.0	$ 113.1
Xenon \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired in-process research and development			$ 36.2

Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Details) - Fair value measurements recurring - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 1,069.5	$ 1,029.3
Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	187.1	112.3
Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	187.1	112.3
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	3.2	3.2
Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	3.2	3.2
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	82.2	144.5
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	445.9	521.9
Securities of government-sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	312.9	191.5
Total debt securities available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	841.0	857.9
Equity securities–biotechnology industry
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	38.2	55.9
Total equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	38.2	55.9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	190.3	115.5
Level 1 \| Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	187.1	112.3
Level 1 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	187.1	112.3
Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3.2	3.2
Level 1 \| Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3.2	3.2
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 1 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 1 \| Securities of government-sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 1 \| Total debt securities available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 1 \| Equity securities–biotechnology industry
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 1 \| Total equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	841.0	857.9
Level 2 \| Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2 \| Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	82.2	144.5
Level 2 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	445.9	521.9
Level 2 \| Securities of government-sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	312.9	191.5
Level 2 \| Total debt securities available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	841.0	857.9
Level 2 \| Equity securities–biotechnology industry
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 2 \| Total equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	38.2	55.9
Level 3 \| Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Restricted cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Securities of government-sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Total debt securities available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Level 3 \| Equity securities–biotechnology industry
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	38.2	55.9
Level 3 \| Total equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	$ 38.2	$ 55.9