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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 02, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	NBIX
Entity Registrant Name	NEUROCRINE BIOSCIENCES INC
Entity Central Index Key	0000914475
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		89,273,537
Entity Public Float			$ 3,407,988,476

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 254,712	$ 83,267
Short-term investments, available-for-sale	261,217	224,083
Accounts receivable	31,127	0
Other current assets	7,863	3,092
Total current assets	554,919	310,442
Property and equipment, net	10,811	6,271
Long-term investments, available-for-sale	247,361	43,490
Restricted cash	4,500	4,883
Total assets	817,591	365,086
Current liabilities:
Accounts payable and accrued liabilities	53,520	26,182
Current portion of deferred rent	0	470
Current portion of cease-use liability	62	236
Current portion of deferred gain on sale of real estate	731	3,526
Other current liabilities	113	0
Total current liabilities	54,426	30,414
Deferred gain on sale of real estate	8,043	7,372
Deferred revenue	10,231	10,231
Deferred rent	3,135	1,462
Convertible senior notes	369,618	0
Cease-use liability	0	617
Other liabilities	0	113
Total liabilities	445,453	50,209
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 220,000,000 shares authorized; issued and outstanding shares were 88,793,903 and 86,883,300 at December 31, 2017 and 2016, respectively	89	87
Additional paid-in capital	1,572,765	1,371,432
Accumulated other comprehensive loss	(1,850)	(318)
Accumulated deficit	(1,198,866)	(1,056,324)
Total stockholders' equity	372,138	314,877
Total liabilities and stockholders' equity	$ 817,591	$ 365,086

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	220,000,000	220,000,000
Common stock, shares issued	88,793,903	86,883,300
Common stock, shares outstanding	88,793,903	86,883,300

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product sales, net	$ 116,626	$ 0	$ 0
Milestones and license fees	45,000	15,000	19,769
Total revenues	161,626	15,000	19,769
Operating expenses:
Cost of product sales	1,254	0	0
Research and development	121,827	94,291	81,491
Sales, general and administrative	169,906	68,081	32,480
Total operating expenses	292,987	162,372	113,971
Loss from operations	(131,361)	(147,372)	(94,202)
Other income:
Deferred gain on real estate	2,124	3,423	3,325
Interest expense	(19,523)	0	0
Investment income, net	6,238	2,838	1,928
Other (expense) income, net	(20)	21	20
Total other income	(11,181)	6,282	5,273
Net loss	$ (142,542)	$ (141,090)	$ (88,929)
Net loss per common share:
Basic	$ (1.62)	$ (1.63)	$ (1.05)
Diluted	$ (1.62)	$ (1.63)	$ (1.05)
Shares used in the calculation of net loss per common share:
Basic	88,089	86,713	84,496
Diluted	88,089	86,713	84,496
Other comprehensive loss:
Net loss	$ (142,542)	$ (141,090)	$ (88,929)
Net unrealized (losses) gains on available-for-sale securities	(1,532)	659	(700)
Comprehensive loss	$ (144,074)	$ (140,431)	$ (89,629)

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive (Loss) Gain	Accumulated Deficit
Beginning balance at Dec. 31, 2014	$ 208,699	$ 76	$ 1,035,205	$ (277)	$ (826,305)
Beginning balance (in shares) at Dec. 31, 2014		76,466
Net loss	(88,929)	$ 0	0	0	(88,929)
Unrealized gains (losses) on investments	(700)	0	0	(700)	0
Share-based compensation	28,392	0	28,392	0	0
Issuance of common stock for restricted share units vested	1	$ 1	0	0	0
Issuance of common stock for restricted share units vested (in shares)		503
Issuance of common stock for option exercises	$ 6,304	$ 1	6,303	0	0
Issuance of common stock for option exercises (in shares)	1,315	1,308
Issuance of common stock, net of offering costs	$ 270,687	$ 8	270,679	0	0
Issuance of common stock, net of offering costs (in shares)		7,986
Ending balance at Dec. 31, 2015	424,454	$ 86	1,340,579	(977)	(915,234)
Ending balance (in shares) at Dec. 31, 2015		86,263
Net loss	(141,090)	$ 0	0	0	(141,090)
Unrealized gains (losses) on investments	659	0	0	659	0
Share-based compensation	28,464	0	28,464	0	0
Issuance of common stock for restricted share units vested	0	$ 0	0	0	0
Issuance of common stock for restricted share units vested (in shares)		284
Issuance of common stock for option exercises	$ 2,390	$ 1	2,389	0	0
Issuance of common stock for option exercises (in shares)	341	336
Ending balance at Dec. 31, 2016	$ 314,877	$ 87	1,371,432	(318)	(1,056,324)
Ending balance (in shares) at Dec. 31, 2016		86,883
Net loss	(142,542)	$ 0	0	0	(142,542)
Unrealized gains (losses) on investments	(1,532)	0	0	(1,532)	0
Share-based compensation	42,522	0	42,522	0	0
Issuance of common stock for restricted share units vested	1	$ 1	0	0	0
Issuance of common stock for restricted share units vested (in shares)		562
Issuance of common stock for option exercises	$ 13,864	$ 1	13,863	0	0
Issuance of common stock for option exercises (in shares)	1,353	1,349
Equity component of convertible debt, net of issuance costs	$ 144,948	$ 0	144,948	0	0
Ending balance at Dec. 31, 2017	$ 372,138	$ 89	$ 1,572,765	$ (1,850)	$ (1,198,866)
Ending balance (in shares) at Dec. 31, 2017		88,794

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOW FROM OPERATING ACTIVITIES
Net loss	$ (142,542)	$ (141,090)	$ (88,929)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,400	1,453	1,009
Gain on sale of assets, net	(2,104)	(3,431)	(3,334)
Cease-use expense	(544)	(584)	(85)
Amortization of debt issuance costs	848	0	0
Amortization of debt discount	10,937	0	0
Deferred revenues	0	0	10,231
Deferred rent	1,203	(294)	(16)
Amortization of premiums on investments	1,756	3,520	6,032
Non-cash share-based compensation expense	42,522	28,464	28,392
Change in operating assets and liabilities:
Accounts receivable	(31,127)	0	0
Inventory	(1,024)	0	0
Other current assets	(3,747)	1,791	(489)
Accounts payable and accrued liabilities	27,338	4,398	9,841
Cease-use liability	(247)	(300)	(610)
Other liabilities	0	(108)	(39)
Net cash used in operating activities	(94,331)	(106,181)	(37,997)
CASH FLOW FROM INVESTING ACTIVITIES
Purchases of investments	(583,408)	(298,776)	(449,052)
Sales/maturities of investments	339,088	415,826	255,123
Deposits and restricted cash	383	(92)	40
Proceeds from sales of property and equipment	7	13	9
Purchases of property and equipment	(6,940)	(4,108)	(1,934)
Net cash (used in) provided by investing activities	(250,870)	112,863	(195,814)
CASH FLOW FROM FINANCING ACTIVITIES
Issuance of common stock	13,865	2,390	276,992
Proceeds from issuance of senior convertible notes, net	502,781	0	0
Net cash provided by financing activities	516,646	2,390	276,992
Net change in cash and cash equivalents	171,445	9,072	43,181
Cash and cash equivalents at beginning of the year	83,267	74,195	31,014
Cash and cash equivalents at end of the year	254,712	83,267	74,195
SUPPLEMENTAL DISCLOSURES
Interest paid	6,242	0	0
Taxes paid	$ 0	$ 0	$ 0

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES *Business Activities.* Neurocrine Biosciences, Inc. (the Company or Neurocrine) was incorporated in California in 1992 and reincorporated in Delaware in 1996. The Company discovers and develops innovative and life-changing pharmaceuticals, in diseases with high unmet medical needs through its novel research and development (R&D) platform focused on neurological, psychological, and endocrine based diseases and disorders. In April 2017, the Company received approval from the United States Food and Drug Administration (FDA) for INGREZZA^® (valbenazine), a vesicular monoamine transporter 2 (VMAT2) inhibitor for the treatment of TD. The Company’s three lead late-stage clinical programs are elagolix, a gonadotropin-releasing hormone (GnRH) antagonist for women’s health that is partnered with AbbVie Inc. (AbbVie), INGREZZA for Tourette syndrome and opicapone, a highly-selective catechol-O-methyltransferase inhibitor for the treatment of Parkinson’s disease. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of the Company. The Company also has two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. which were formed in December 2014, both of which are inactive. *Principles of Consolidation.* The consolidated financial statements include the accounts of Neurocrine as well as its wholly owned subsidiaries. The Company does not have any significant interests in any variable interest entities. 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 (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. *Cash Equivalents.* The Company considers 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. *Short-Term and Long-Term Investments Available-for-Sale.* Certain investments are classified as available-for-sale and, in accordance with authoritative guidance, are carried at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in investment income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in investment income. *Concentration of Credit Risk.* Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, investments and accounts receivables. The Company has established guidelines to limit its exposure to credit risk by placing investments with high credit quality financial institutions, diversifying its investment portfolio and placing investments with maturities that maintain safety and liquidity. *Inventory.* Inventory is stated at the lower of cost or estimated net realizable value. The Company currently uses actual costing to determine the cost basis for its inventory. Inventory is valued on a first-in, first-out basis and consists primarily of third-party manufacturing costs. The Company capitalizes inventory costs associated with its products upon regulatory approval when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized; otherwise, such costs are expensed. Prior to FDA approval of INGREZZA, all costs related to its manufacturing were charged to research and development expense in the period incurred. At December 31, 2017, the Company’s physical inventory included active pharmaceutical product that had been produced prior to FDA approval of INGREZZA and accordingly has no cost basis as the cost associated with producing this material was expensed rather than capitalized in accordance with authoritative guidance. Additionally, manufacturing of bulk drug product, finished bottling and other labeling activities that occurred post FDA approval are included in the inventory value at December 31, 2017. The Company provides reserves for potential excess, dated or obsolete inventory based on an analysis of forecasted demand compared to quantities on hand and any firm purchase orders, as well as product shelf life. To date, the Company has determined that such reserves are not required. *Cost of Product Sales.* Cost of product sales consists of third-party manufacturing costs, transportation and freight, and indirect overhead costs associated with the manufacture and distribution of INGREZZA. Cost of product sales may also include period costs related to certain inventory manufacturing services, inventory adjustment charges as well as manufacturing variances. A significant portion of the cost of producing the product sold during the year ended December 31, 2017 was expensed as R&D prior to the Company’s New Drug Application (NDA) approval for INGREZZA and therefore is not included in the cost of product sales during this period. *Accounts Receivable.* Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks, and any allowance for doubtful accounts. The Company estimates the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of its customers and individual customer circumstances. To date, the Company has determined that an allowance for doubtful accounts is not required. *Advertising Expense.* In connection with the FDA approval and commercial launch of INGREZZA in 2017, the Company began to incur advertising costs. Advertising costs are expensed when services are performed or goods are delivered. The Company incurred $10.1 million in advertising costs in 2017 related to its marketed product, INGREZZA. No advertising costs were capitalized as prepaid expenses at December 31, 2017. *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. *Industry Segment and Geographic Information.* The Company operates in a single industry segment – the discovery, development and marketing of therapeutics for the treatment of neurological and endocrine based diseases and disorders. The Company had no foreign based operations during any of the years presented. All revenue is generated in the United States. *Impairment of Long-Lived Assets.* The Company reviews 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, the Company assesses 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, the Company measures 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. *Fair Value of Financial Instruments.* Certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable, and accrued liabilities, are carried at cost, which management believes approximates fair value because of the short-term maturity of these instruments. Convertible senior notes were recorded at the estimated value of a similar non-convertible instrument on the date of issuance and accretes to face value of the notes over the seven year term. The fair value of the 2024 Notes is estimated utilizing market quotations from an over-the-counter trading market. As of December 31, 2017, the fair value approximated 128 percent of the face principal amount of the convertible senior notes. *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 contractor 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 the Company’s independent R&D efforts as well as efforts associated with collaborations and in-licensing arrangements. In addition, the Company funds R&D at other companies and research institutions under agreements, which are generally cancelable. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. *Revenue Recognition.* *Product Sales, Net.* The Company’s net product sales consist of U.S. sales of INGREZZA and are recognized when (i) persuasive evidence of an arrangement exists, (ii) delivery has occurred and title to the product and associated risk of loss has passed to the customer, (iii) the price is fixed or determinable, and (iv) collectability is reasonably assured. INGREZZA was approved by the FDA on April 11, 2017 and the Company commenced shipments of INGREZZA to select pharmacies (SPs) and a select distributor (SD) in late April 2017. The SPs dispense product to a patient based on the fulfillment of a prescription and the SD sells product to government facilities, long-term care pharmacies or in-patient hospital pharmacies. The Company’s agreements with SPs and SDs provide for transfer of title to the product at the time the product is delivered to the SP or SD. In addition, except for limited circumstances, the SPs and SDs have no right of product return to the Company. The Company has determined it can reasonably estimate its sales allowances at the time title and risk of loss transfers to the SP or SD. Therefore, the Company records revenue when the product is delivered to the SPs or SD, which is an approach frequently referred to as the “sell-in” revenue recognition model. The Company recognizes revenue from product sales net of the following allowances: Distribution Fees: Distribution fees include fees paid to the SPs and SD for data, prompt payment discounts and other off-invoice discounts. Distribution fees are recorded as an offset to gross revenue based on contractual terms at the time revenue from the sale is recognized. Government Rebates: Government rebates include mandated discounts under the Medicaid Drug Rebate Program and the Medicare Part D prescription drug benefit. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and result from contractual agreements with, or statutory requirements pertaining to, Medicaid and Medicare benefit providers. The allowance for rebates is based on statutory discount rates, expected utilization and expected trends in net reimbursement. Expected utilization of rebates is based on prescription level detail provided by the SPs that includes insurer amounts for each prescription filled during the period as well as the limited amount of product that is in the SPs warehouse at period end. Chargebacks: Chargebacks are discounts that relate to contracts with government and other entities purchasing from the SD at a discounted price. The SD charges back to the Company the difference between the price initially paid by the SD and the discounted price paid to the SD by these entities. Chargebacks are recorded as an offset to gross revenue at the time revenue from the product sale is recognized based on known and expected SD sales to these entities. Co-Payment Assistance: The Company offers co-payment assistance to commercially insured patients meeting certain eligibility requirements. Co-payment assistance is recorded as an offset to gross revenue at the time revenue from the product sale is recognized based on expected and actual program participation. Expected program participation is based on prescription level detail provided by the SPs that includes copay amounts for each prescription filled during the period as well as the limited amount of product that is in the SPs warehouse at period end. Product Returns: The Company offers the SPs and SD limited product return rights for damages and shipment errors provided it is within a very limited period after the original shipping date as set forth in the applicable individual distribution agreement. The Company does not allow product returns for product that has been dispensed to a patient or for drug expiration. The Company receives real-time shipping reports and inventory reports from the SPs and SD and has the ability to control the amount of product that is sold to the SPs and SD. It is also able to make a reasonable estimate of potential product returns due to the limited time-frame allowed for the SPs and SD to process returns due to shipment error or damaged product. *Collaborative Research and Development Agreements.* Since 2011, the Company has followed the Accounting Standards Codification (ASC) for Revenue Recognition – Multiple-Element Arrangements, if applicable, to determine the recognition of revenue under license and collaboration agreements. The ASC provides guidance relating to the separation of deliverables included in an arrangement into different units of accounting and the allocation of consideration to the units of accounting. The evaluation of multiple-element arrangements requires management to make judgments about (i) the identification of deliverables, (ii) whether such deliverables are separable from the other aspects of the contractual relationship, (iii) the estimated selling price of each deliverable, and (iv) the expected period of performance for each deliverable. To determine the units of accounting under a multiple-element arrangement, the Company evaluates certain separation criteria, including whether the deliverables have stand-alone value, based on the relevant facts and circumstances for each arrangement. The selling prices of deliverables under an arrangement may be derived using vendor specific objective evidence (VSOE), third-party evidence, or a best estimate of selling price (BESP), if VSOE or third-party evidence is not available. For most pharmaceutical licensing and collaboration agreements, BESP is utilized. Establishing BESP involves judgment and considers multiple factors, including market conditions and company-specific factors, including those factors contemplated in negotiating the agreements, as well as internally developed models that include assumptions related to market opportunity, discounted cash flows, estimated development costs, probability of success and the time needed to commercialize a product candidate pursuant to the agreement. In validating the BESP, the Company considers whether changes in key assumptions used to determine the BESP will have a significant effect on the allocation of the arrangement consideration between the multiple deliverables. The allocated consideration for each unit of accounting is recognized over the related obligation period in accordance with the applicable revenue recognition criteria. If there are deliverables in an arrangement that are not separable from other aspects of the contractual relationship, they are treated as a combined unit of accounting, with the allocated revenue for the combined unit recognized in a manner consistent with the revenue recognition applicable to the final deliverable in the combined unit. Payments received prior to satisfying the relevant revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets and recognized as revenue when the related revenue recognition criteria are met. The Company typically receives up-front payments when licensing its intellectual property, which often occurs in conjunction with an R&D agreement. The Company will recognize revenue attributed to the license upon delivery, provided that the license has stand-alone value. Milestones are recognized when earned, as evidenced by written acknowledgment from the collaborator or other persuasive evidence that the milestone has been achieved, provided that the milestone event is substantive. A milestone event is generally considered to be substantive if its achievability was not reasonably assured at the inception of the agreement. The Company assesses whether a milestone is substantive at the inception of each agreement. *Share-Based Compensation.* The Company estimates the fair value of stock options using the Black-Scholes option pricing model on the date of grant. Restricted stock units are valued based on the closing price of the Company’s 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 the Company’s equity compensation plans provide for shorter vesting periods under certain circumstances. Additionally, the Company has granted certain performance-based equity awards that vest upon the achievement of certain pre-defined Company-specific performance criteria. Expense related to these performance-based equity awards is generally recognized ratably over the performance period once the pre-defined performance based criteria for vesting becomes probable. *Investment Income, Net.* Investment income, net is comprised of interest and dividends earned on cash, cash equivalents and investments as well as gains and losses realized from activity in the Company’s investment portfolio. For the years ended December 31, 2017, 2016 and 2015, the investment income was $6.2 million, $2.8 million and $1.9 million, respectively and primarily consisted of interest income. *Net Loss Per Share.* The Company computes basic net loss per share using the weighted average number of common shares outstanding during the period. Diluted net income per share is based upon the weighted average number of common shares and potentially dilutive securities (common share equivalents) outstanding during the period. Common share equivalents outstanding, determined using the treasury stock method, are comprised of shares that may be issued under the Company’s stock option agreements or convertible debt. Common share equivalents are excluded from the diluted net loss per share calculation because of their anti-dilutive effect. Due to the Company’s net loss position in 2017, 2016 and 2015, approximately 3.4 million, 3.8 million and 4.1 million, respectively, of common share equivalents related to outstanding restricted stock units and employee options were excluded from the diluted common shares outstanding. For the years ended December 31, 2017, 2016 and 2015, there were employee stock options, calculated on a weighted average basis, to purchase 0.4 million, 0.4 million, and 0.1 million shares of our common stock with an exercise price greater than the average market price of the underlying common shares. Additionally, during May 2017 the Company issued $517.5 million of convertible debt which under certain circumstances may convert to common shares outstanding. If converted, this $517.5 million of convertible debt would represent approximately 6.8 million common shares. *Impact of Recently Issued Accounting Standards.* In May 2014 the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. This new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date. These new standards became effective for us on January 1, 2018, and will be adopted using the modified retrospective method through a cumulative-effect adjustment, if any, directly to retained earnings as of that date. The Company has performed a review of these new standards as compared to our current accounting policies for customer contracts and collaborative relationships. As of December 31, 2017, the Company has not identified any accounting changes that would materially impact the amount of reported revenues with respect to our product revenues. The Company is currently evaluating the impact of the new standard on historical revenue recorded for our two collaboration agreements. This ongoing evaluation is dependent upon the resolution of certain questions relating to the application of the new revenue recognition guidance for collaboration agreements which will ultimately determine the impact, if any, the adoption of this standard may have on the consolidated financial statements. The company expects the accounting for contingent milestone payments to be the most significant change in accounting for its license and collaboration agreements. Topic 605 provides guidance specific to the accounting for milestone payments, including the ability to defer the recognition of any milestones until received and, if certain criteria are met, the ability to recognize milestone payments as revenue when received. However, Topic 606 does not contain guidance specific to milestone payments, thereby requiring potential milestone payments to be considered in accordance with the overall model of Topic 606. As a result, revenues from contingent milestone payments may be recognized earlier under Topic 606 than under Topic 605, based on an assessment of the probability of achievement of the milestone and the likelihood of a significant reversal of such milestone revenue at each reporting date. This assessment may result in recognizing milestone revenue before the milestone event has been achieved. In addition, Topic 606 changes guidance regarding the accounting for variable consideration received from licensees, which may impact the estimation of, and determination of the timing of, the related revenue recognition. In February 2016, the FASB issued Accounting Standards Update (ASU) 2016-02 Leases. This update amends the current accounting guidance for lease transactions. Under the new guidance, a lessee will be required to recognize both assets and liabilities for any leases in excess of twelve months. Additionally, certain qualitative and quantitative disclosures will also be required in the financial statements. The Company is required to adopt this new guidance beginning in 2019 and early adoption is permitted. The Company’s lease for its corporate headquarters is subject to this new guidance and the process of determining the impact of the adoption of this update will have on its consolidated financial statements is ongoing. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”, which clarifies the presentation of restricted cash and restricted cash equivalents in the statements of cash flows. Under this ASU, restricted cash and restricted cash equivalents are included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the statements of cash flows. This ASU is intended to reduce diversity in practice in the classification and presentation of changes in restricted cash on the statement of cash flows. This ASU requires that the statement of cash flows explain the change in total cash and equivalents and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. This ASU also requires a reconciliation between the total of cash and equivalents and restricted cash presented on the statement of cash flows and the cash and equivalents balance presented on the balance sheet. This ASU was effective for the Company on January 1, 2018. The Company does not expect the adoption of this ASU to have a material effect on its results of operations, financial condition or cash flows.

SIGNIFICANT COLLABORATIVE RESEARCH AND DEVELOPMENT AGREEMENTS	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
SIGNIFICANT COLLABORATIVE RESEARCH AND DEVELOPMENT AGREEMENTS	NOTE 2. SIGNIFICANT COLLABORATIVE RESEARCH AND DEVELOPMENT AGREEMENTS *Mitsubishi Tanabe Pharma Corporation (Mitsubishi Tanabe).* During 2015, the Company entered into a collaboration and license agreement with Mitsubishi Tanabe for the development and commercialization of INGREZZA for movement disorders in Japan and other select Asian markets. Payments to the Company under this agreement include an up-front license fee of $30 million, up to $85 million in development and commercialization event-based payments, payments for the manufacture of pharmaceutical products, and royalties on product sales in select territories in Asia. Under the terms of the agreement, Mitsubishi Tanabe is responsible for all third-party development, marketing and commercialization costs in Japan and other select Asian markets with the exception of a single Huntington’s chorea clinical trial to be performed by the Company, at an estimated cost of approximately $12 million, should Mitsubishi Tanabe request the clinical trial. The Company will 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. Under the terms of the Company’s agreement with Mitsubishi Tanabe, the collaboration effort between the parties to advance INGREZZA towards commercialization in Japan and other select Asian markets is governed by a joint steering committee and joint development committee with representatives from both the Company and Mitsubishi Tanabe. There are no performance, cancellation, termination or refund provisions in the agreement that would have a material financial consequence to the Company. The Company does not directly control when event-based payments will be achieved or when royalty payments will begin. Mitsubishi Tanabe may terminate the agreement at its discretion upon 180 days’ written notice to the Company. In such event, all INGREZZA product rights for Japan and other select Asian markets would revert to the Company. The Company has identified the following deliverables associated with the Mitsubishi Tanabe agreement: INGREZZA technology license and existing know-how, development activities to be performed as part of the collaboration, and the manufacture of pharmaceutical products. The respective standalone value from each of these deliverables has been determined by applying the BESP method and the revenue was allocated based on the relative selling price method with revenue recognition timing to be determined either by delivery or the provision of services. As discussed above, the BESP method required the use of significant estimates. The Company used an income approach to estimate the selling price for the technology license and an expense approach for estimating development activities and the manufacture of pharmaceutical products. The development activities and the manufacture of pharmaceutical products are expected to be delivered throughout the duration of the agreement. The technology license and existing know-how was delivered on the effective date of the agreement. For the year ended December 31, 2017, the Company recognized $15 million in development event-based payments resulting from Mitsubishi Tanabe’s initiation of Phase II/III development of INGREZZA in TD in Asia. No revenue was recognized under the Mitsubishi Tanabe agreement for the year ended December 31, 2016. For the year ended December 31, 2015, the Company recognized revenue under this agreement of $19.8 million associated with the delivery of a technology license and existing know-how. In accordance with our continuing performance obligations, $10.2 million of the $30 million up-front payment is being deferred and recognized in future periods. Under the terms of the agreement, there is no general obligation to return the up-front payment for any non-contingent deliverable. *AbbVie Inc. (AbbVie)*. In June 2010, the Company announced an exclusive worldwide collaboration with AbbVie, to develop and commercialize elagolix and all next-generation GnRH antagonists (collectively, GnRH Compounds) for women’s and men’s health. AbbVie made an upfront payment of $75 million and has agreed to make additional development and regulatory event-based payments of up to $480 million, of which $75 million has been earned to date, and up to an additional $50 million in commercial event-based payments. The Company has assessed event-based payments under the revised authoritative guidance for research and development milestones and determined that event-based payments prior to commencement of a Phase III clinical study, as defined in the agreement, meet the definition of a milestone in accordance with authoritative guidance as (1) they are events that can only be achieved in part on the Company’s past performance, (2) there is substantive uncertainty at the date the arrangement was entered into that the event will be achieved and (3) they result in additional payments being due to the Company. Development and regulatory event-based payments subsequent to the commencement of a Phase III clinical study, however, currently do not meet these criteria as their achievement is based on the performance of AbbVie. As of December 31, 2017, approximately $455 million remains outstanding in future event-based payments under the agreement as the performance is based solely on AbbVie. However, none of the remaining event-based payments meet the definition of a milestone in accordance with authoritative accounting guidance. Under the terms of the agreement, AbbVie is responsible for all third-party development, marketing and commercialization costs. The Company will be entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights. AbbVie may terminate the collaboration at its discretion upon 180 days’ written notice to the Company. In such event, the Company would be entitled to specified payments for ongoing clinical development and related activities and all GnRH Compound product rights would revert to the Company. During 2017, event-based revenue of $30.0 million was recognized based on AbbVie’s NDA submission for elagolix in endometriosis being accepted as filed by the FDA. During 2016, event-based revenue of $15.0 million was recognized related to AbbVie’s initiation of Phase III development of elagolix in uterine fibroids. No revenue was recognized during 2015 under this collaboration agreement.

INVESTMENTS

12 Months Ended

Dec. 31, 2017

Investments Schedule [Abstract]

INVESTMENTS

NOTE 3. INVESTMENTS

Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in comprehensive loss. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in investment income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in investment income.

Investments at December 31, 2017 and 2016 consisted of the following (in thousands):


	Years Ended December 31,
	2017		2016
Certificates of deposit	$	—	$	960
Commercial paper		75,362		49,245
Corporate debt securities		414,815		204,436
Securities of government-sponsored entities		18,401		12,932

Total investments	$	508,578	$	267,573

The following is a summary of investments classified as available-for-sale securities (in thousands):


	Contractual Maturity (in years)		Amortized Cost		Gross Unrealized Gains(1)		Gross Unrealized Losses(1)			Aggregate Estimated Fair Value
December 31, 2016:
Classified as current assets:
Certificates of deposit		Less than 1	$	960	$	—	$	—		$	960
Commercial paper		Less than 1		49,280		3		(38	)		49,245
Corporate debt securities		Less than 1		168,548		3		(117	)		168,434
Securities of government-sponsored entities		Less than 1		5,448		—		(4	)		5,444

Total short-term available-for-sale securities			$	224,236	$	6	$	(159	)	$	224,083

Classified as non-current assets:
Corporate debt securities		1 to 2	$	36,149	$	—	$	(147	)	$	36,002
Securities of government-sponsored entities		1 to 2		7,506		—		(18	)		7,488

Total long-term available-for-sale securities			$	43,655	$	—	$	(165	)	$	43,490

December 31, 2017:
Classified as current assets:
Commercial paper		Less than 1	$	75,396	$	1	$	(35	)	$	75,362
Corporate debt securities		Less than 1		178,776		—		(400	)		178,376
Securities of government-sponsored entities		Less than 1		7,503		—		(24	)		7,479

Total short-term available-for-sale securities			$	261,675	$	1	$	(459	)	$	261,217

Classified as non-current assets:
Corporate debt securities		1 to 2	$	237,749	$	—	$	(1,310	)	$	236,439
Securities of government-sponsored entities		1 to 2		11,004		—		(82	)		10,922

Total long-term available-for-sale securities			$	248,753	$	—	$	(1,392	)	$	247,361

(1)	Unrealized gains and losses are included in other comprehensive loss.

The following table presents gross unrealized losses and fair value for those available-for-sale investments that were in an unrealized loss position as of December 31, 2017 and 2016, aggregated by investment category and length of time that individual securities have been in a continuous loss position (in thousands):


	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
December 31, 2016:
Commercial paper	$	43,781	$	(38	)	$	—	$	—		$	43,781	$	(38	)
Corporate debt securities		185,243		(261	)		9,144		(3	)		194,387		(264	)
Securities of government-sponsored entities		12,932		(22	)		—		—			12,932		(22	)

Total	$	241,956	$	(321	)	$	9,144	$	(3	)	$	251,100	$	(324	)

December 31, 2017:
Commercial paper	$	62,602	$	(35	)	$	—	$	—		$	62,602	$	(35	)
Corporate debt securities		386,728		(1,660	)		28,087		(50	)		414,815		(1,710	)
Securities of government-sponsored entities		10,922		(82	)		7,479		(24	)		18,401		(106	)

Total	$	460,252	$	(1,777	)	$	35,566	$	(74	)	$	495,818	$	(1,851	)

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

NOTE 4. FAIR VALUE MEASUREMENTS

Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:


Level 1:		Observable inputs such as quoted prices in active markets;

Level 2:		Inputs include quoted prices for similar instruments in active markets and/or quoted prices for identical or similar instruments in markets that are not active near the measurement date; and

Level 3:		Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

The Company classifies its cash equivalents and available for sale investments within Level 1 or Level 2. The fair value of the Company’s high quality investment grade corporate debt securities is determined using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. The Company did not reclassify any investments between levels in the fair value hierarchy during the years ended December 31, 2017 and 2016.

The Company’s assets which are measured at fair value on a recurring basis as of December 31, 2017 and 2016 were determined using the inputs described above (in millions):


				Fair Value Measurements Using
	Carrying Value			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
December 31, 2016:
Classified as current assets:
Cash and money market funds	$	73.6		$	73.6		$	—		$	—
Certificates of deposit		1.0			1.0			—			—
Commercial paper		49.2			—			49.2			—
Securities of government-sponsored entities		5.4			—			5.4			—
Corporate debt securities		178.1			—			178.1			—

Subtotal		307.3			74.6			232.7			—
Classified as long-term assets:
Certificates of deposit		4.9			4.9			—			—
Securities of government-sponsored entities		7.5			—			7.5			—
Corporate debt securities		36.0			—			36.0			—

Total		355.7			79.5			276.2			—
Less cash, cash equivalents and restricted cash		(88.1	)		(78.5	)		(9.6	)		—

Total investments	$	267.6		$	1.0		$	266.6		$	—

December 31, 2017:
Classified as current assets:
Cash and money market funds	$	170.2		$	170.2		$	—		$	—
Commercial paper		159.9			—			159.9			—
Securities of government-sponsored entities		7.5			—			7.5			—
Corporate debt securities		178.4			—			178.4			—

Subtotal		516.0			170.2			345.8			—
Classified as long-term assets:
Cash and money market funds		1.5			1.5
Certificates of deposit		3.0			3.0			—			—
Securities of government-sponsored entities		10.9			—			10.9			—
Corporate debt securities		236.4			—			236.4			—

Total		767.8			174.7			593.1			—
Less cash, cash equivalents and restricted cash		(259.2	)		(174.6	)		(84.6	)		—

Total investments	$	508.6		$	0.1		$	508.5		$	—

The fair value of the Company’s outstanding 2.25% convertible senior notes due 2024 (the 2024 Notes) at December 31, 2017, calculated utilizing market quotations from an over-the-counter trading market for these notes (Level 2), was approximately $662.1 million. The carrying value of the 2024 Notes is discussed in Note 8 to the Consolidated Financial Statements included in this Annual Report .

- 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

PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

NOTE 5. PROPERTY AND EQUIPMENT

Property and equipment, net, at December 31, 2017 and 2016 consisted of the following (in thousands):


	December 31,
	2017			2016
Tenant improvements		2,019			1,530
Furniture and fixtures		1,303			942
Equipment		35,069			29,749

		38,391			32,221
Less accumulated depreciation		(27,580	)		(25,950	)

Property and equipment, net	$	10,811		$	6,271

For each of the years ended December 31, 2017, 2016 and 2015, depreciation expense was $2.4 million, $1.5 million and $1.0 million, respectively. During 2017, 2016 and 2015, the Company recognized a gain of approximately $7,000, $8,000 and $9,000, respectively, related to disposal of capital equipment.

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

NOTE 6. ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

Accounts payable and accrued liabilities at December 31, 2017 and 2016 consisted of the following (in thousands):


	December 31,
	2017		2016
Accrued employee related costs	$	24,901	$	9,559
Accounts payable		5,648		5,085
Accrued development costs		4,799		5,543
Other accrued liabilities		18,172		5,995

	$	53,520	$	26,182

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

NOTE 7. COMMITMENTS AND CONTINGENCIES

In December 2007, the Company closed the sale of its facility and associated real property for a purchase price of $109 million. Concurrent with the sale, the Company retired the entire $47.7 million in mortgage debt previously outstanding with respect to the facility and associated real property, and received cash of $61.0 million net of transaction costs and debt retirement.

Upon the closing of the sale of the facility and associated real property, the Company entered into a lease agreement (Lease) whereby it leased back for an initial term of 12 years its corporate headquarters comprised of two buildings located at 12790 El Camino Real (Front Building) and 12780 El Camino Real (Rear Building) in San Diego, California. The Company also entered into a series of lease amendments (Amendments), beginning in late 2008 through 2011, through which it was able to vacate the Front Building, but continue to occupy the Rear Building. The ultimate result of this real estate sale was a net gain of $39.1 million which was deferred in accordance with authoritative guidance. The Company recognized $2.1 million, $3.4 million and $3.3 million of the deferred gain during the years ended December 31, 2017, 2016 and 2015, respectively. The Company will recognize the remaining $8.8 million of the deferred gain on a straight-line basis over the amended Lease term which will expire at the end of 2029.

During 2017, the Company entered into an amendment to extend the current term of the Lease through December 31, 2029 (Term Amendment). Under the Term Amendment, the Company reduced its base rental rate by approximately 8% and will continue to pay base annual rent (subject to an annual fixed percentage increase), plus a 3.5% annual management fee, property taxes and other normal and necessary expenses associated with the Lease such as utilities, repairs and maintenance. Certain incentives were included in the Term Amendment, including approximately $13.1 million in various tenant improvement allowances, three months of rent abatement, and a reduction in the required security deposit amount from $4.7 million to $3.0 million. In lieu of a cash security deposit, Wells Fargo Bank, N.A. issued on the Company’s behalf a letter of credit in the amount of $3.0 million, which is secured by a deposit of equal amount with the same bank. The Company also has the right to extend the Lease for two consecutive ten-year terms as well as a right of first offer for future rental of adjacent office space owned by the landlord.

As of December 31, 2017, the Company had one sublease agreement for approximately 16,000 square feet of the Rear Building. This sublease is expected to result in approximately $0.1 million of rental income in 2018 with this sublease rental income being recorded as an offset to rent expense. The income generated under this sublease is lower than the Company’s financial obligation under the Lease for the Rear Building, as determined on a per square foot basis. Consequently, at the inception of a sublease, or in association with an amendment to a sublease, the Company is required to record a cease-use liability for the net present value of the estimated difference between the expected income to be generated under the sublease and future subleases and the Lease obligation over the remaining term of the Lease for the space that is occupied by the subtenant. As a result of the recent FDA approval for INGREZZA and the Term Amendment, the Company has determined that it will reoccupy the space at the conclusion of the sublease in March 2018. Additionally, during the first quarter of 2016, the Company terminated another previously existing sublease and began to reoccupy the related space to allow for expansion. These two sublease terminations resulted in reversal of cease use expense of approximately $0.5 million and $0.8 million during 2017 and 2016, respectively.

The following table sets forth changes to the accrued cease-use liability during 2017 and 2016 (in thousands):


	Years Ended December 31,
	2017			2016
Beginning balance	$	853		$	1,983
Change in estimate		(544	)		(830	)
Payments		(247	)		(300	)

Ending balance	$	62		$	853

Rent Expense. Gross rent expense was approximately $5.9 million for the year ended December 31, 2017, and $6.0 million for each of the years ended December 31, 2016 and 2015, respectively. For financial reporting purposes, the Company recognizes rent expense on a straight-line basis over the term of the lease. Accordingly, rent expense recognized in excess of rent paid is reflected as a liability in the accompanying consolidated balance sheets.

Lease Commitments. The Company leases its office and research laboratories under an operating lease that expires at the end of 2029.

As of December 31, 2017, the total estimated future annual minimum lease payments under the Company’s non-cancelable building lease for the years ending after December 31, 2017 were as follows (in thousands):


	Payment Amount
2018	$	7,368
2019		7,589
2020		7,844
2021		8,079
2022 and thereafter		74,000

Total future minimum lease payments	$	104,880

Product Liability. The Company’s business exposes it to liability risks from its potential drug products. A successful product liability claim or series of claims brought against the Company could result in payment of significant amounts of money and divert management’s attention from running the business. The Company may not be able to maintain insurance on acceptable terms, or the insurance may not provide adequate protection in the case of a product liability claim. To the extent that product liability insurance, if available, does not cover potential claims, the Company would be required to self-insure the risks associated with such claims. The Company believes that it carries reasonably adequate insurance for product liability claims.

Licensing and Research Agreements. The Company has entered into in-licensing agreements with various universities and research organizations, which are generally cancelable at the option of the Company with terms ranging from 0-180 days written notice. Under the terms of these agreements, the Company has received licenses to research tools, know-how and technology claimed in certain patents or patent applications. The Company is required to pay fees, milestones and/or royalties on future sales of products employing the technology or falling under claims of a patent, and some of the agreements require minimum royalty payments. Some of the agreements also require the Company to pay expenses arising from the prosecution and maintenance of the patents covering the in-licensed technology. The Company continually reassesses the value of the license agreements and cancels them when research efforts are discontinued on these programs. As of December 31, 2017, all in-licensed and research candidates are successfully developed, the Company may be required to pay milestone payments of approximately $132 million over the lives of these agreements, in addition to royalties on sales of the affected products at rates ranging up to 5%. Due to the uncertainties of the development process, the timing and probability of the milestone and royalty payments cannot be accurately estimated.

Litigation. From time to time, the Company may be subject to legal proceedings and claims in the ordinary course of business. On December 1, 2015, Icahn School of Medicine at Mount Sinai (Mount Sinai) filed a complaint against the Company in the United States District Court for the Southern District of New York: Icahn School of Medicine at Mount Sinai v. Neurocrine Biosciences, Inc., Case No. 1:15-cv-09414. In the complaint, Mount Sinai alleges that the Company, by entering into an exclusive worldwide collaboration with AbbVie to develop and commercialize next-generation GnRH antagonists, breached a license agreement with Mount Sinai dated August 27, 1999 (Mount Sinai License). Mount Sinai is seeking unspecified monetary damages, future sublicensing fees and attorney’s fees. In January 2016, the Company filed a motion to dismiss this complaint in its entirety. In June 2016, the Court denied the motion in part and granted the motion in part, ruling that while Mount Sinai could continue its lawsuit against the Company, there was no requirement by the Company to obtain Mount Sinai’s consent prior to licensing the next-generation GnRH antagonists to AbbVie. In July 2016, the Company filed its answer denying Mount Sinai’s allegations, and filed counterclaims against Mount Sinai. Mount Sinai filed a motion to dismiss the Company’s counterclaims and affirmative defenses, which the Court granted. A trial is anticipated to occur in the first half of 2018.The Company believes that it has meritorious defenses to the claims made in the complaint and intends to vigorously defend against such claims, but is not able to predict the ultimate outcome of this action, or estimate any potential loss.

The Company is not aware of any other proceedings or claims that it believes will have, individually or in the aggregate, a material adverse effect on its business, financial condition or results of operations.

CONVERTIBLE SENIOR NOTES

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

CONVERTIBLE SENIOR NOTES

NOTE 8. CONVERTIBLE SENIOR NOTES

On May 2, 2017, the Company completed a private placement of $517.5 million in aggregate principal amount of 2.25% convertible senior notes due 2024 (2024 Notes) and entered into an indenture agreement (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 the Company.

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

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

(ii) during the five business-day period immediately after any five 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 the Company’s 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 the Company’s assets; or

(iv) if the Company calls 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 the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s option.

It is the Company’s intent and policy to settle conversions through combination settlement, which essentially involves repayment of an amount of cash equal to the “principal portion” and delivery of the “share amount” in excess of the principal portion in shares of common stock or cash. In general, for each $1,000 in principal, the “principal portion” of cash upon settlement is defined as the lesser of $1,000, and the conversion value during the 25-day observation period as described in the indenture for the notes. The conversion value is the sum of the daily conversion value which is the product of the effective conversion rate divided by 25 days and the daily volume weighted average price (VWAP) of the Company’s 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 the Company’s common stock. 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 represents a premium of approximately 42.5% to the closing sale price of $53.28 per share of the Company’s common stock on the NASDAQ Global Select Market on April 26, 2017, the date that the Company 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, the Company would be required to repay the $517.5 million in principal value and any conversion premium in any combination of cash and shares of its common stock (at the Company’s option).

Prior to May 15, 2021, the Company may not redeem the 2024 Notes. On or after May 15, 2021, the Company may redeem for cash all or part of the 2024 Notes if the last reported sale price (as defined in the 2024 Indenture) of the Company’s 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 the Company provides 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 the Company undergoes a fundamental change, as defined in the 2024 Indenture, subject to certain conditions, holders of the 2024 Notes may require the Company 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, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its notes in connection with the make-whole fundamental change.

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

While the 2024 Notes are currently classified on the Company’s consolidated balance sheet at December 31, 2017 as long-term, the future convertibility and resulting balance sheet classification of this liability will be monitored at each quarterly reporting date and will be analyzed dependent upon market prices of the Company’s common stock during the prescribed measurement periods. In the event that the holders of the 2024 Notes have the election to convert the 2024 Notes at any time during the prescribed measurement period, the 2024 Notes would then be considered a current obligation and classified as such.

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

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

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

Debt, net of discounts and deferred financing costs at December 31, 2017, consisted of the following:


Principal	$	517,500
Deferred financing costs		(9,652	)
Debt discount, net		(138,230	)

Net carrying amount	$	369,618

SHARE-BASED COMPENSATION

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

SHARE-BASED COMPENSATION

NOTE 9. SHARE-BASED COMPENSATION

Share-Based Compensation Plans. In May 2011, the Company adopted the Neurocrine Biosciences, Inc. 2011 Equity Incentive Plan (the 2011 Plan) pursuant to which 17.0 million shares of Company common stock are authorized for issuance. The 2011 Plan provides for the grant of stock options that qualify as incentive stock options under Section 422 of the Internal Revenue Code of 1986, as amended (the Code), nonstatutory stock options, restricted stock awards, restricted stock unit awards (RSUs), stock appreciation rights, performance stock awards, performance-based restricted stock units (PRSUs) and other forms of equity compensation.

The Company also issues stock options under the Neurocrine Biosciences, Inc. Inducement Plan (Inducement Plan) to certain employees. During 2017 and 2015, 410,000 and 120,000 stock options, respectively, and during 2017 and 2015, 12,500 and 50,000 RSUs, respectively, were granted pursuant to the Inducement Plan. The Company did not grant any options or RSUs pursuant to the Inducement Plan during 2016. These stock option grants have a four year vesting period and the RSUs have a three year cliff vesting period. The Company currently has approximately 0.4 million in stock options and RSUs outstanding under this Inducement Plan.

As of December 31, 2017, approximately 6.3 million shares of common stock remained available for the future grant of awards under the 2011 Plan. Only share awards made under the 2011 Plan that are subsequently cancelled due to forfeiture or expiration are returned to the share pool available for future grants.

The Company issues new shares upon the exercise of stock options, the issuance of stock bonus awards and vesting of RSUs and PRSUs, and has 14.1 million shares of common stock reserved for such issuance as of December 31, 2017.

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

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


	Years Ended December 31,
	2017		2016		2015
Sales, general and administrative expense	$	27,951	$	16,770	$	15,281
Research and development expense		14,571		11,694		13,111

Share-based compensation expense	$	42,522	$	28,464	$	28,392

Authoritative guidance requires that cash flows resulting from tax deductions in excess of the cumulative compensation cost recognized for options exercised be classified as cash inflows provided by financing activities and cash outflows used in operating activities. Due to the Company’s net tax loss position, no tax benefits have been recognized in the consolidated statements of cash flows.

Stock Options. The exercise price of all options granted during the years ended December 31, 2017, 2016 and 2015 was equal to the closing price of the Company’s common stock on the date of grant. The estimated fair value of each option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for option grants during the three years ended December 31, 2017:


	Years Ended December 31,
	2017			2016			2015
Risk-free interest rate		2.0	%		1.4	%		1.7	%
Expected volatility of common stock		58	%		60	%		66	%
Dividend yield		0.0	%		0.0	%		0.0	%
Expected option term		5.7 years			5.6 years			6.6 years

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

The Company’s determination of fair value is affected by the Company’s stock price as well as a number of assumptions that require judgment. The weighted-average fair values of options granted during the years ended December 31, 2017, 2016 and 2015, estimated as of the grant date using the Black-Scholes option valuation model, were $25.11, $21.49 and $23.24, respectively.

A summary of the status of the Company’s stock options as of December 31, 2017, 2016 and 2015 and of changes in options outstanding under the plans during the three years ended December 31, 2017 is as follows (in thousands, except for weighted average exercise price data):


	2017					2016					2015
	Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price
Outstanding at January 1		6,112		$	20.01		5,507		$	15.63		5,750		$	9.31
Granted		1,807			46.55		1,077			40.19		1,159			37.21
Exercised		(1,353	)		10.41		(341	)		7.60		(1,315	)		5.01
Canceled		(210	)		43.05		(131	)		34.35		(87	)		46.08

Outstanding at December 31		6,356		$	28.83		6,112		$	20.01		5,507		$	15.63

Options outstanding at December 31, 2017 have a weighted average remaining contractual term of 6.7 years.

For the year ended December 31, 2017, 2016 and 2015 share-based compensation expense related to stock options was $28.2 million, $18.4 million and $13.6 million, respectively. As of December 31, 2017, there was approximately $44.0 million of unamortized compensation cost related to stock options, which is expected to be recognized over a weighted average remaining vesting period of approximately 2.7 years. As of December 31, 2017, there were approximately 4.2 million options exercisable with a weighted average exercise price of $21.22 and a weighted-average remaining contractual term of 5.7 years. The total intrinsic value, which is the amount by which the exercise price was exceeded by the sale price of the Company’s common stock on the date of sale, of stock option exercises during the years ended December 31, 2017, 2016, and 2015 was $61.4 million, $13.2 million and $43.6 million, respectively. As of December 31, 2017, the total intrinsic value of options outstanding and exercisable was $309.9 million and $234.9 million, respectively. Cash received from stock option exercises for the years ended December 31, 2017, 2016 and 2015 was $13.9 million, $2.4 million and $6.3 million, respectively.

Restricted Stock Units. The fair value of RSUs is based on the closing sale price of the Company’s common stock on the date of issuance. For the year ended December 31, 2017, 2016 and 2015, share-based compensation expense related to RSUs was $13.9 million, $8.3 million, and $6.0 million, respectively. As of December 31, 2017, there was approximately $30.0 million of unamortized compensation cost related to RSUs, which is expected to be recognized over a weighted average remaining vesting period of approximately 2.7 years.

The total intrinsic value of RSUs converted into common shares during the years ended December 31, 2017, 2016 and 2015 was $14.9 million, $12.2 million, and $5.7 million, respectively. The RSUs, at the election of eligible employees, may be subject to deferred delivery arrangement. The total intrinsic value of RSUs outstanding at December 31, 2017 was $83.8 million based on the Company’s closing stock price on that date.

A summary of the status of the Company’s RSUs as of December 31, 2017, 2016 and 2015 and of changes in RSUs outstanding under the plans for the three years ended December 31, 2017 is as follows (in thousands, except for weighted average grant date fair value per unit):


	2017					2016					2015
	Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit
Outstanding at January 1		883		$	29.33		910		$	24.23		669		$	15.01
Granted		588			47.21		326			36.73		448			33.62
Cancelled		(41	)		40.62		(69	)		32.50		(16	)		20.83
Converted into common shares		(350	)		24.19		(284	)		20.71		(191	)		14.24

Outstanding at December 31		1,080		$	40.30		883		$	29.33		910		$	24.23

Performance-Based Restricted Stock Units. During the years ended December 31, 2016 and 2015, the Company granted approximately 230,000 and 50,000 PRSUs, respectively, that vest based on the achievement of certain pre-defined Company-specific performance criteria and expire approximately four to five years from the grant date. No PRSUs were granted during the year ended December 31, 2017. The fair value of PRSUs is estimated based on the closing sale price of the Company’s common stock on the date of grant. Expense recognition for PRSUs commences when attainment of the performance based criteria is determined to be probable. During 2017, 2016 and 2015, the Company recognized approximately $0.4 million, $1.8 million and $8.8 million in expense related to PRSUs. At December 31, 2017, the total unrecognized estimated compensation expense related to these PRSUs was $7.5 million. The total intrinsic value of PRSUs converted into common shares during the year ended December 31, 2017 and 2015 was $8.8 million and $14.9 million, respectively. No PRSUs were converted into common shares during 2016. The total intrinsic value of PRSUs outstanding at December 31, 2017 was $16.3 million based on the Company’s closing stock price on that date.

STOCKHOLDERS' EQUITY	12 Months Ended
STOCKHOLDERS' EQUITY	Dec. 31, 2017
Equity [Abstract]
STOCKHOLDERS' EQUITY	NOTE 10. STOCKHOLDERS’ EQUITY *Equity Financing* In February 2015, the Company completed a public offering of common stock in which the Company sold approximately 8.0 million shares of its common stock at an offering price of $36.00 per share. The net proceeds generated from this transaction, after underwriting discounts and commissions and offering costs, were approximately $270.7 million.

BIAL AGREEMENT	12 Months Ended
BIAL AGREEMENT	Dec. 31, 2017
Text Block [Abstract]
BIAL AGREEMENT	NOTE 11. BIAL AGREEMENT In February 2017, the Company entered into an exclusive license agreement with BIAL – Portela & CA, S.A. (BIAL) for the development and commercialization of opicapone for the treatment of human diseases and conditions, including Parkinson’s disease, in the United States and Canada. Under the terms of the agreement, the Company is responsible for the management and cost of all opicapone development and commercialization activities in the United States and Canada. Under the terms of the agreement, the Company paid BIAL an upfront license fee of $30 million, which was expensed in the first quarter of 2017 as in process research and development. The Company may also be required to pay up to an additional $115 million in milestone payments associated with the regulatory approval and net sales of products containing opicapone. Prior to FDA approval of opicapone, the Company may be required to pay up to $20 million in milestones based on certain regulatory and clinical results and FDA acceptance of the Company’s NDA filing for opicapone. Upon commercialization of opicapone, the Company has agreed to determine certain annual sales forecasts. In the event that the Company fails to meet the minimum sales requirements for a particular year, the Company will be required to pay BIAL an amount corresponding to the difference between the actual net sales and the minimum sales requirements for such year, and if the Company fails to meet the minimum sales requirements for any two years, BIAL may terminate the agreement. The agreement, unless terminated earlier, will continue on a licensed product-by-licensed product and country-by-country basis until a generic product in respect of such licensed product under the agreement is sold in a country and sales of such generic product are greater than a specified percentage of total sales of such licensed product in such country. Upon the Company’s written request prior to the estimated expiration of the term in respect of a licensed product, the parties shall negotiate a good faith continuation of BIAL’s supply of such licensed product after the term. After the term, and if BIAL is not supplying a certain licensed product, the Company shall pay BIAL a trademark royalty based on the net sales of such licensed product. Either party may terminate the agreement earlier if the other party materially breaches the agreement and does not cure the breach within a specified notice period, or upon the other party’s insolvency. BIAL may terminate the agreement if the Company fails to use commercially reasonable efforts or fails to file an NDA for a licensed product by a specified date or under certain circumstances involving a change of control of the Company. In certain circumstances where BIAL elects to terminate the agreement in connection with the Company’s change of control, BIAL shall pay the Company a termination fee. The Company may terminate the agreement at any time for any reason upon six months written notice to BIAL if prior to the first NDA approval in the United States, and upon nine months written notice to BIAL if such notice is given after the first NDA approval in the United States. If the Company’s termination request occurs prior to the first NDA approval in the United States, the Company will have to pay BIAL a termination fee except under certain conditions specified in the agreement.

CONCENTRATION RISK	12 Months Ended
CONCENTRATION RISK	Dec. 31, 2017
Risks and Uncertainties [Abstract]
CONCENTRATION RISK	NOTE 12. CONCENTRATION RISK The Company does not currently have any of its own manufacturing facilities, and therefore it depends on an outsourced manufacturing strategy for the production of INGREZZA for commercial use and for the production of its product candidates for clinical trials. The Company has contracts in place with one third-party manufacturer that is approved for the commercial production of INGREZZA’s capsules and one third-party manufacturer that is approved for the production of INGREZZA’s active pharmaceutical ingredient. Although there are potential sources of supply other than the Company’s existing suppliers, any new supplier would be required to qualify under applicable regulatory requirements. The Company has entered into distribution agreements with a limited number of SPs and SDs, and all of the Company’s product sales are to these customers. The Company’s three largest customers represented 99% of the Company’s product revenue for the year ended December 31, 2017 and substantially all of the Company’s accounts receivable balance at December 31, 2017.

INCOME TAXES

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

INCOME TAXES

NOTE 13. INCOME TAXES

At December 31, 2017, the Company had deferred tax assets of $362.7 million and deferred tax liabilities of $31.8 million. Due to uncertainties surrounding the Company’s ability to generate future taxable income, a full valuation has been established to offset the net deferred tax assets and liabilities. Additionally, the future utilization of the Company’s net operating loss and R&D credit carry forwards 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. The Company has determined that no ownership changes have occurred through December 31, 2016 and is currently evaluating whether any ownership changes occurred through December 31, 2017.

At December 31, 2017, the Company had Federal and state income tax net operating loss carry forwards of approximately $978.7 million and $535.3 million, respectively. The Federal tax loss carry forwards will begin to expire in 2021, unless previously utilized.

The California net operating loss carry forwards will begin to expire in 2018 and net operating loss carry forwards related to other states will begin to expire in 2027.

In addition, the Company has Federal and California R&D tax credit carry forwards of $48.2 million and $34.6 million, respectively. The Federal R&D tax credit carry forwards begin expiring in 2018 and will continue to expire unless utilized. The California R&D tax credit carryforwards carry forward indefinitely. The Company also has Federal Alternative Minimum Tax credit carryforwards of approximately $100,000.

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the 2017 Tax Act) was enacted reducing the corporate tax rate from 35% to 21% which is effective on January 1, 2018. The carrying value of the Company’s deferred tax assets is also determined by the enacted U.S. corporate income tax rate. Consequently, any changes in the U.S. corporate income tax rate have impacted the carrying value of the Company’s deferred tax assets. Under the new corporate income tax rate of 21%, deferred income taxes decreased but there is a corresponding decrease to the valuation allowance. Therefore, the 2017 Tax Act is expected to have no impact on the Company’s 2017 earnings. In accordance with Staff Accounting Bulletin 118, as of December 31, 2017, the Company has not completed its accounting for the tax effects of the enactment of the 2017 Tax Act; however, the Company has made a reasonable estimate of the effects on its existing deferred tax balances.

Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2017 and 2016 are listed below. A valuation allowance of $330.9 million and $463.5 million at December 31, 2017 and 2016, respectively, has been recognized to offset net deferred tax assets as realization of such assets is uncertain. Amounts are shown as of December 31 as of each respective year (in thousands):


	2017			2016
Deferred tax assets:
Net operating losses	$	238,500		$	309,100
Research and development credits		47,500			38,800
Capitalized research and development		47,500			80,200
Share-based compensation expense		14,600			17,400
Deferred revenue		2,800			4,300
Deferred gain on sales leaseback		2,100			3,800
Intangibles		1,700			4,800
Cease-use expense		—			300
Fixed assets		—			400
Other		8,000			4,400

Total deferred tax assets		362,700			463,500
Deferred tax liabilities:
Convertible debt		(31,300	)		—
Fixed assets		(500	)		—

Total deferred tax liabilities		(31,800	)		—

Net of deferred tax assets and liabilities		330,900			463,500
Valuation allowance		(330,900	)		(463,500	)

Net deferred tax assets	$	—		$	—

The provision for income taxes on earnings subject to income taxes differs from the statutory Federal rate at December 31, 2017, 2016 and 2015, due to the following (in thousands):


	2017			2016			2015
Federal income taxes at 35%	$	(49,889	)	$	(49,383	)	$	(31,126	)
State income tax, net of Federal benefit		(4,013	)		2			2
Tax effect on non-deductible expenses		433			(321	)		172
Share-based compensation expense		(19,589	)		(5,077	)		201
Officer compensation		2,163			—			—
Change in tax rate		154,415			—			10,773
Expired tax attributes		2,998			6,708			5,594
Research credits		(8,352	)		(6,511	)		(6,638	)
Change in valuation allowance		(79,966	)		53,414			15,029
Uncertain tax positions		2,756			957			5,940
Other		(956	)		211			53

	$	—		$	—		$	—

Under the FASB’s accounting guidance related to uncertain tax positions, among other things, 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. Additionally, the guidance provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.

The Company’s policy is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had no accrual for interest or penalties on the Company’s consolidated balance sheets at December 31, 2017 or December 31, 2016, and has not recognized interest and/or penalties in the statement of comprehensive loss for the years ended December 31, 2017 and December 31, 2016.

The Company is subject to taxation in the United States and various state jurisdictions. The Company’s tax years for 1998 (federal) and 2002 (California) and forward are subject to examination by the United States and California tax authorities due to the carry forward of unutilized net operating losses and R&D credits.

The following table summarizes the activity related to our unrecognized tax benefits (in thousands):


	2017		2016			2015
Balance as of the beginning of the year	$	34,112	$	33,074		$	23,854
Increases related to prior year tax positions		—		260			6,636
Increases related to current year tax positions		3,291		2,211			2,584
Expiration of the statute of limitations for the assessment of taxes		—		(1,433	)		—

Balance as of the end of the year	$	37,403	$	34,112		$	33,074

The Company, under authoritative guidance, excluded those deferred tax assets that are not more likely than not to be sustained under the technical merits of the tax position. These unrecognized tax benefits totaled $3.3 million for current year tax positions, as reflected in the tabular rollforward above.

As of December 31, 2017, the Company had $30.7 million of unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate.

In the next twelve months, the Company does not expect a significant change in their unrecognized tax benefits.

RETIREMENT PLAN	12 Months Ended
RETIREMENT PLAN	Dec. 31, 2017
Retirement Benefits [Abstract]
RETIREMENT PLAN	NOTE 14. RETIREMENT PLAN The Company has a 401(k) defined contribution savings plan (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 $1.1 million, $0.6 million and $0.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)

NOTE 15. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)

The following is a summary of the quarterly results of the Company for the years ended December 31, 2017 and 2016 (unaudited, in thousands, except for per share data):


	Year Ended December 31,												Year Ended December 31
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter			Year Ended December 31
2016:
Revenues	$	15,000		$	—		$	—		$	—		$	15,000
Operating expenses		35,857			41,828			38,436			46,251			162,372
Net loss		(19,264	)		(40,280	)		(36,887	)		(44,659	)		(141,090	)
Net loss per share:
Basic and Diluted	$	(0.22	)	$	(0.46	)	$	(0.43	)	$	(0.51	)	$	(1.63	)
Shares used in the calculation of net loss per share:
Basic and Diluted		86,497			86,694			86,784			86,874			86,713
2017:
Revenues	$	—		$	6,335		$	60,774		$	94,517		$	161,626
Operating expenses		79,932			63,603			66,769			82,683			292,987
Net (loss) income		(78,326	)		(59,985	)		(11,125	)		6,894			(142,542	)
Net (loss) income per share:
Basic	$	(0.90	)	$	(0.68	)	$	(0.13	)	$	0.08		$	(1.62	)
Diluted	$	(0.90	)	$	(0.68	)	$	(0.13	)	$	0.07		$	(1.62	)
Shares used in the calculation of net (loss) income per share:
Basic		87,283			88,063			88,325			88,665			88,089
Diluted		87,283			88,063			88,325			92,659			88,089

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Business Activities	*Business Activities.* Neurocrine Biosciences, Inc. (the Company or Neurocrine) was incorporated in California in 1992 and reincorporated in Delaware in 1996. The Company discovers and develops innovative and life-changing pharmaceuticals, in diseases with high unmet medical needs through its novel research and development (R&D) platform focused on neurological, psychological, and endocrine based diseases and disorders. In April 2017, the Company received approval from the United States Food and Drug Administration (FDA) for INGREZZA^® (valbenazine), a vesicular monoamine transporter 2 (VMAT2) inhibitor for the treatment of TD. The Company’s three lead late-stage clinical programs are elagolix, a gonadotropin-releasing hormone (GnRH) antagonist for women’s health that is partnered with AbbVie Inc. (AbbVie), INGREZZA for Tourette syndrome and opicapone, a highly-selective catechol-O-methyltransferase inhibitor for the treatment of Parkinson’s disease. Neurocrine Continental, Inc., is a Delaware corporation and a wholly owned subsidiary of the Company. The Company also has two wholly-owned Irish subsidiaries, Neurocrine Therapeutics, Ltd. and Neurocrine Europe, Ltd. which were formed in December 2014, both of which are inactive.
Principles of Consolidation	*Principles of Consolidation.* The consolidated financial statements include the accounts of Neurocrine as well as its wholly owned subsidiaries. The Company does not have any significant interests in any variable interest entities. 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 (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.
Cash Equivalents	*Cash Equivalents.* The Company considers 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.
Short-Term and Long-Term Investments Available-for-Sale	*Short-Term and Long-Term Investments Available-for-Sale.* Certain investments are classified as available-for-sale and, in accordance with authoritative guidance, are carried at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in investment income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in investment income.
Concentration of Credit Risk	*Concentration of Credit Risk.* Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, investments and accounts receivables. The Company has established guidelines to limit its exposure to credit risk by placing investments with high credit quality financial institutions, diversifying its investment portfolio and placing investments with maturities that maintain safety and liquidity.
Inventory	*Inventory.* Inventory is stated at the lower of cost or estimated net realizable value. The Company currently uses actual costing to determine the cost basis for its inventory. Inventory is valued on a first-in, first-out basis and consists primarily of third-party manufacturing costs. The Company capitalizes inventory costs associated with its products upon regulatory approval when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized; otherwise, such costs are expensed. Prior to FDA approval of INGREZZA, all costs related to its manufacturing were charged to research and development expense in the period incurred. At December 31, 2017, the Company’s physical inventory included active pharmaceutical product that had been produced prior to FDA approval of INGREZZA and accordingly has no cost basis as the cost associated with producing this material was expensed rather than capitalized in accordance with authoritative guidance. Additionally, manufacturing of bulk drug product, finished bottling and other labeling activities that occurred post FDA approval are included in the inventory value at December 31, 2017. The Company provides reserves for potential excess, dated or obsolete inventory based on an analysis of forecasted demand compared to quantities on hand and any firm purchase orders, as well as product shelf life. To date, the Company has determined that such reserves are not required.
Cost of Product Sales	*Cost of Product Sales.* Cost of product sales consists of third-party manufacturing costs, transportation and freight, and indirect overhead costs associated with the manufacture and distribution of INGREZZA. Cost of product sales may also include period costs related to certain inventory manufacturing services, inventory adjustment charges as well as manufacturing variances. A significant portion of the cost of producing the product sold during the year ended December 31, 2017 was expensed as R&D prior to the Company’s New Drug Application (NDA) approval for INGREZZA and therefore is not included in the cost of product sales during this period.
Accounts Receivable	*Accounts Receivable.* Accounts receivable are recorded net of customer allowances for prompt payment discounts, chargebacks, and any allowance for doubtful accounts. The Company estimates the allowance for doubtful accounts based on existing contractual payment terms, actual payment patterns of its customers and individual customer circumstances. To date, the Company has determined that an allowance for doubtful accounts is not required.
Advertising Expense	*Advertising Expense.* In connection with the FDA approval and commercial launch of INGREZZA in 2017, the Company began to incur advertising costs. Advertising costs are expensed when services are performed or goods are delivered. The Company incurred $10.1 million in advertising costs in 2017 related to its marketed product, INGREZZA. No advertising costs were capitalized as prepaid expenses at December 31, 2017.
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.
Industry Segment and Geographic Information	*Industry Segment and Geographic Information.* The Company operates in a single industry segment – the discovery, development and marketing of therapeutics for the treatment of neurological and endocrine based diseases and disorders. The Company had no foreign based operations during any of the years presented. All revenue is generated in the United States.
Impairment of Long-Lived Assets	*Impairment of Long-Lived Assets.* The Company reviews 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, the Company assesses 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, the Company measures 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.
Fair Value of Financial Instruments	*Fair Value of Financial Instruments.* Certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable, and accrued liabilities, are carried at cost, which management believes approximates fair value because of the short-term maturity of these instruments. Convertible senior notes were recorded at the estimated value of a similar non-convertible instrument on the date of issuance and accretes to face value of the notes over the seven year term. The fair value of the 2024 Notes is estimated utilizing market quotations from an over-the-counter trading market. As of December 31, 2017, the fair value approximated 128 percent of the face principal amount of the convertible senior notes.
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 contractor 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 the Company’s independent R&D efforts as well as efforts associated with collaborations and in-licensing arrangements. In addition, the Company funds R&D at other companies and research institutions under agreements, which are generally cancelable. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known.
Revenue Recognition	*Revenue Recognition.* *Product Sales, Net.* The Company’s net product sales consist of U.S. sales of INGREZZA and are recognized when (i) persuasive evidence of an arrangement exists, (ii) delivery has occurred and title to the product and associated risk of loss has passed to the customer, (iii) the price is fixed or determinable, and (iv) collectability is reasonably assured. INGREZZA was approved by the FDA on April 11, 2017 and the Company commenced shipments of INGREZZA to select pharmacies (SPs) and a select distributor (SD) in late April 2017. The SPs dispense product to a patient based on the fulfillment of a prescription and the SD sells product to government facilities, long-term care pharmacies or in-patient hospital pharmacies. The Company’s agreements with SPs and SDs provide for transfer of title to the product at the time the product is delivered to the SP or SD. In addition, except for limited circumstances, the SPs and SDs have no right of product return to the Company. The Company has determined it can reasonably estimate its sales allowances at the time title and risk of loss transfers to the SP or SD. Therefore, the Company records revenue when the product is delivered to the SPs or SD, which is an approach frequently referred to as the “sell-in” revenue recognition model. The Company recognizes revenue from product sales net of the following allowances: Distribution Fees: Distribution fees include fees paid to the SPs and SD for data, prompt payment discounts and other off-invoice discounts. Distribution fees are recorded as an offset to gross revenue based on contractual terms at the time revenue from the sale is recognized. Government Rebates: Government rebates include mandated discounts under the Medicaid Drug Rebate Program and the Medicare Part D prescription drug benefit. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and result from contractual agreements with, or statutory requirements pertaining to, Medicaid and Medicare benefit providers. The allowance for rebates is based on statutory discount rates, expected utilization and expected trends in net reimbursement. Expected utilization of rebates is based on prescription level detail provided by the SPs that includes insurer amounts for each prescription filled during the period as well as the limited amount of product that is in the SPs warehouse at period end. Chargebacks: Chargebacks are discounts that relate to contracts with government and other entities purchasing from the SD at a discounted price. The SD charges back to the Company the difference between the price initially paid by the SD and the discounted price paid to the SD by these entities. Chargebacks are recorded as an offset to gross revenue at the time revenue from the product sale is recognized based on known and expected SD sales to these entities. Co-Payment Assistance: The Company offers co-payment assistance to commercially insured patients meeting certain eligibility requirements. Co-payment assistance is recorded as an offset to gross revenue at the time revenue from the product sale is recognized based on expected and actual program participation. Expected program participation is based on prescription level detail provided by the SPs that includes copay amounts for each prescription filled during the period as well as the limited amount of product that is in the SPs warehouse at period end. Product Returns: The Company offers the SPs and SD limited product return rights for damages and shipment errors provided it is within a very limited period after the original shipping date as set forth in the applicable individual distribution agreement. The Company does not allow product returns for product that has been dispensed to a patient or for drug expiration. The Company receives real-time shipping reports and inventory reports from the SPs and SD and has the ability to control the amount of product that is sold to the SPs and SD. It is also able to make a reasonable estimate of potential product returns due to the limited time-frame allowed for the SPs and SD to process returns due to shipment error or damaged product.
Collaborative Research and Development Agreements	*Collaborative Research and Development Agreements.* Since 2011, the Company has followed the Accounting Standards Codification (ASC) for Revenue Recognition – Multiple-Element Arrangements, if applicable, to determine the recognition of revenue under license and collaboration agreements. The ASC provides guidance relating to the separation of deliverables included in an arrangement into different units of accounting and the allocation of consideration to the units of accounting. The evaluation of multiple-element arrangements requires management to make judgments about (i) the identification of deliverables, (ii) whether such deliverables are separable from the other aspects of the contractual relationship, (iii) the estimated selling price of each deliverable, and (iv) the expected period of performance for each deliverable. To determine the units of accounting under a multiple-element arrangement, the Company evaluates certain separation criteria, including whether the deliverables have stand-alone value, based on the relevant facts and circumstances for each arrangement. The selling prices of deliverables under an arrangement may be derived using vendor specific objective evidence (VSOE), third-party evidence, or a best estimate of selling price (BESP), if VSOE or third-party evidence is not available. For most pharmaceutical licensing and collaboration agreements, BESP is utilized. Establishing BESP involves judgment and considers multiple factors, including market conditions and company-specific factors, including those factors contemplated in negotiating the agreements, as well as internally developed models that include assumptions related to market opportunity, discounted cash flows, estimated development costs, probability of success and the time needed to commercialize a product candidate pursuant to the agreement. In validating the BESP, the Company considers whether changes in key assumptions used to determine the BESP will have a significant effect on the allocation of the arrangement consideration between the multiple deliverables. The allocated consideration for each unit of accounting is recognized over the related obligation period in accordance with the applicable revenue recognition criteria. If there are deliverables in an arrangement that are not separable from other aspects of the contractual relationship, they are treated as a combined unit of accounting, with the allocated revenue for the combined unit recognized in a manner consistent with the revenue recognition applicable to the final deliverable in the combined unit. Payments received prior to satisfying the relevant revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets and recognized as revenue when the related revenue recognition criteria are met. The Company typically receives up-front payments when licensing its intellectual property, which often occurs in conjunction with an R&D agreement. The Company will recognize revenue attributed to the license upon delivery, provided that the license has stand-alone value. Milestones are recognized when earned, as evidenced by written acknowledgment from the collaborator or other persuasive evidence that the milestone has been achieved, provided that the milestone event is substantive. A milestone event is generally considered to be substantive if its achievability was not reasonably assured at the inception of the agreement. The Company assesses whether a milestone is substantive at the inception of each agreement.
Share-Based Compensation	*Share-Based Compensation.* The Company estimates the fair value of stock options using the Black-Scholes option pricing model on the date of grant. Restricted stock units are valued based on the closing price of the Company’s 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 the Company’s equity compensation plans provide for shorter vesting periods under certain circumstances. Additionally, the Company has granted certain performance-based equity awards that vest upon the achievement of certain pre-defined Company-specific performance criteria. Expense related to these performance-based equity awards is generally recognized ratably over the performance period once the pre-defined performance based criteria for vesting becomes probable.
Investment Income, Net	*Investment Income, Net.* Investment income, net is comprised of interest and dividends earned on cash, cash equivalents and investments as well as gains and losses realized from activity in the Company’s investment portfolio. For the years ended December 31, 2017, 2016 and 2015, the investment income was $6.2 million, $2.8 million and $1.9 million, respectively and primarily consisted of interest income.
Net Loss Per Share	*Net Loss Per Share.* The Company computes basic net loss per share using the weighted average number of common shares outstanding during the period. Diluted net income per share is based upon the weighted average number of common shares and potentially dilutive securities (common share equivalents) outstanding during the period. Common share equivalents outstanding, determined using the treasury stock method, are comprised of shares that may be issued under the Company’s stock option agreements or convertible debt. Common share equivalents are excluded from the diluted net loss per share calculation because of their anti-dilutive effect. Due to the Company’s net loss position in 2017, 2016 and 2015, approximately 3.4 million, 3.8 million and 4.1 million, respectively, of common share equivalents related to outstanding restricted stock units and employee options were excluded from the diluted common shares outstanding. For the years ended December 31, 2017, 2016 and 2015, there were employee stock options, calculated on a weighted average basis, to purchase 0.4 million, 0.4 million, and 0.1 million shares of our common stock with an exercise price greater than the average market price of the underlying common shares. Additionally, during May 2017 the Company issued $517.5 million of convertible debt which under certain circumstances may convert to common shares outstanding. If converted, this $517.5 million of convertible debt would represent approximately 6.8 million common shares.
Impact of Recently Issued Accounting Standards	*Impact of Recently Issued Accounting Standards.* In May 2014 the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. This new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date. These new standards became effective for us on January 1, 2018, and will be adopted using the modified retrospective method through a cumulative-effect adjustment, if any, directly to retained earnings as of that date. The Company has performed a review of these new standards as compared to our current accounting policies for customer contracts and collaborative relationships. As of December 31, 2017, the Company has not identified any accounting changes that would materially impact the amount of reported revenues with respect to our product revenues. The Company is currently evaluating the impact of the new standard on historical revenue recorded for our two collaboration agreements. This ongoing evaluation is dependent upon the resolution of certain questions relating to the application of the new revenue recognition guidance for collaboration agreements which will ultimately determine the impact, if any, the adoption of this standard may have on the consolidated financial statements. The company expects the accounting for contingent milestone payments to be the most significant change in accounting for its license and collaboration agreements. Topic 605 provides guidance specific to the accounting for milestone payments, including the ability to defer the recognition of any milestones until received and, if certain criteria are met, the ability to recognize milestone payments as revenue when received. However, Topic 606 does not contain guidance specific to milestone payments, thereby requiring potential milestone payments to be considered in accordance with the overall model of Topic 606. As a result, revenues from contingent milestone payments may be recognized earlier under Topic 606 than under Topic 605, based on an assessment of the probability of achievement of the milestone and the likelihood of a significant reversal of such milestone revenue at each reporting date. This assessment may result in recognizing milestone revenue before the milestone event has been achieved. In addition, Topic 606 changes guidance regarding the accounting for variable consideration received from licensees, which may impact the estimation of, and determination of the timing of, the related revenue recognition. In February 2016, the FASB issued Accounting Standards Update (ASU) 2016-02 Leases. This update amends the current accounting guidance for lease transactions. Under the new guidance, a lessee will be required to recognize both assets and liabilities for any leases in excess of twelve months. Additionally, certain qualitative and quantitative disclosures will also be required in the financial statements. The Company is required to adopt this new guidance beginning in 2019 and early adoption is permitted. The Company’s lease for its corporate headquarters is subject to this new guidance and the process of determining the impact of the adoption of this update will have on its consolidated financial statements is ongoing. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”, which clarifies the presentation of restricted cash and restricted cash equivalents in the statements of cash flows. Under this ASU, restricted cash and restricted cash equivalents are included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the statements of cash flows. This ASU is intended to reduce diversity in practice in the classification and presentation of changes in restricted cash on the statement of cash flows. This ASU requires that the statement of cash flows explain the change in total cash and equivalents and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. This ASU also requires a reconciliation between the total of cash and equivalents and restricted cash presented on the statement of cash flows and the cash and equivalents balance presented on the balance sheet. This ASU was effective for the Company on January 1, 2018. The Company does not expect the adoption of this ASU to have a material effect on its results of operations, financial condition or cash flows.

INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Investments Schedule [Abstract]

Investments

Investments at December 31, 2017 and 2016 consisted of the following (in thousands):


	Years Ended December 31,
	2017		2016
Certificates of deposit	$	—	$	960
Commercial paper		75,362		49,245
Corporate debt securities		414,815		204,436
Securities of government-sponsored entities		18,401		12,932

Total investments	$	508,578	$	267,573

Summary of Investments Classified as Available-For-Sale Securities

The following is a summary of investments classified as available-for-sale securities (in thousands):


	Contractual Maturity (in years)		Amortized Cost		Gross Unrealized Gains(1)		Gross Unrealized Losses(1)			Aggregate Estimated Fair Value
December 31, 2016:
Classified as current assets:
Certificates of deposit		Less than 1	$	960	$	—	$	—		$	960
Commercial paper		Less than 1		49,280		3		(38	)		49,245
Corporate debt securities		Less than 1		168,548		3		(117	)		168,434
Securities of government-sponsored entities		Less than 1		5,448		—		(4	)		5,444

Total short-term available-for-sale securities			$	224,236	$	6	$	(159	)	$	224,083

Classified as non-current assets:
Corporate debt securities		1 to 2	$	36,149	$	—	$	(147	)	$	36,002
Securities of government-sponsored entities		1 to 2		7,506		—		(18	)		7,488

Total long-term available-for-sale securities			$	43,655	$	—	$	(165	)	$	43,490

December 31, 2017:
Classified as current assets:
Commercial paper		Less than 1	$	75,396	$	1	$	(35	)	$	75,362
Corporate debt securities		Less than 1		178,776		—		(400	)		178,376
Securities of government-sponsored entities		Less than 1		7,503		—		(24	)		7,479

Total short-term available-for-sale securities			$	261,675	$	1	$	(459	)	$	261,217

Classified as non-current assets:
Corporate debt securities		1 to 2	$	237,749	$	—	$	(1,310	)	$	236,439
Securities of government-sponsored entities		1 to 2		11,004		—		(82	)		10,922

Total long-term available-for-sale securities			$	248,753	$	—	$	(1,392	)	$	247,361

(1)	Unrealized gains and losses are included in other comprehensive loss.

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


	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
December 31, 2016:
Commercial paper	$	43,781	$	(38	)	$	—	$	—		$	43,781	$	(38	)
Corporate debt securities		185,243		(261	)		9,144		(3	)		194,387		(264	)
Securities of government-sponsored entities		12,932		(22	)		—		—			12,932		(22	)

Total	$	241,956	$	(321	)	$	9,144	$	(3	)	$	251,100	$	(324	)

December 31, 2017:
Commercial paper	$	62,602	$	(35	)	$	—	$	—		$	62,602	$	(35	)
Corporate debt securities		386,728		(1,660	)		28,087		(50	)		414,815		(1,710	)
Securities of government-sponsored entities		10,922		(82	)		7,479		(24	)		18,401		(106	)

Total	$	460,252	$	(1,777	)	$	35,566	$	(74	)	$	495,818	$	(1,851	)

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Assets Measured at Fair Value on Recurring Basis

The Company’s assets which are measured at fair value on a recurring basis as of December 31, 2017 and 2016 were determined using the inputs described above (in millions):


				Fair Value Measurements Using
	Carrying Value			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
December 31, 2016:
Classified as current assets:
Cash and money market funds	$	73.6		$	73.6		$	—		$	—
Certificates of deposit		1.0			1.0			—			—
Commercial paper		49.2			—			49.2			—
Securities of government-sponsored entities		5.4			—			5.4			—
Corporate debt securities		178.1			—			178.1			—

Subtotal		307.3			74.6			232.7			—
Classified as long-term assets:
Certificates of deposit		4.9			4.9			—			—
Securities of government-sponsored entities		7.5			—			7.5			—
Corporate debt securities		36.0			—			36.0			—

Total		355.7			79.5			276.2			—
Less cash, cash equivalents and restricted cash		(88.1	)		(78.5	)		(9.6	)		—

Total investments	$	267.6		$	1.0		$	266.6		$	—

December 31, 2017:
Classified as current assets:
Cash and money market funds	$	170.2		$	170.2		$	—		$	—
Commercial paper		159.9			—			159.9			—
Securities of government-sponsored entities		7.5			—			7.5			—
Corporate debt securities		178.4			—			178.4			—

Subtotal		516.0			170.2			345.8			—
Classified as long-term assets:
Cash and money market funds		1.5			1.5
Certificates of deposit		3.0			3.0			—			—
Securities of government-sponsored entities		10.9			—			10.9			—
Corporate debt securities		236.4			—			236.4			—

Total		767.8			174.7			593.1			—
Less cash, cash equivalents and restricted cash		(259.2	)		(174.6	)		(84.6	)		—

Total investments	$	508.6		$	0.1		$	508.5		$	—

PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment, net, at December 31, 2017 and 2016 consisted of the following (in thousands):


	December 31,
	2017			2016
Tenant improvements		2,019			1,530
Furniture and fixtures		1,303			942
Equipment		35,069			29,749

		38,391			32,221
Less accumulated depreciation		(27,580	)		(25,950	)

Property and equipment, net	$	10,811		$	6,271

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

Accounts Payable and Accrued Liabilities

Accounts payable and accrued liabilities at December 31, 2017 and 2016 consisted of the following (in thousands):


	December 31,
	2017		2016
Accrued employee related costs	$	24,901	$	9,559
Accounts payable		5,648		5,085
Accrued development costs		4,799		5,543
Other accrued liabilities		18,172		5,995

	$	53,520	$	26,182

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Changes to Accrued Cease-Use Liability

The following table sets forth changes to the accrued cease-use liability during 2017 and 2016 (in thousands):


	Years Ended December 31,
	2017			2016
Beginning balance	$	853		$	1,983
Change in estimate		(544	)		(830	)
Payments		(247	)		(300	)

Ending balance	$	62		$	853

Estimated Future Annual Minimum Lease Payments


	Payment Amount
2018	$	7,368
2019		7,589
2020		7,844
2021		8,079
2022 and thereafter		74,000

Total future minimum lease payments	$	104,880

CONVERTIBLE SENIOR NOTES (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt Net of Discount and Deferred Financing Costs

Debt, net of discounts and deferred financing costs at December 31, 2017, consisted of the following:


Principal	$	517,500
Deferred financing costs		(9,652	)
Debt discount, net		(138,230	)

Net carrying amount	$	369,618

- 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://www.xbrl.org/2003/role/presentationRef
-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=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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 4: http://www.xbrl.org/2003/role/presentationRef
-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=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

SHARE-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Compensation Cost Related to Share Based Compensation

The compensation cost that has been included in the statement of comprehensive loss for all share-based compensation arrangements is as follows (in thousands):


	Years Ended December 31,
	2017		2016		2015
Sales, general and administrative expense	$	27,951	$	16,770	$	15,281
Research and development expense		14,571		11,694		13,111

Share-based compensation expense	$	42,522	$	28,464	$	28,392

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

The estimated fair value of each option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for option grants during the three years ended December 31, 2017:


	Years Ended December 31,
	2017			2016			2015
Risk-free interest rate		2.0	%		1.4	%		1.7	%
Expected volatility of common stock		58	%		60	%		66	%
Dividend yield		0.0	%		0.0	%		0.0	%
Expected option term		5.7 years			5.6 years			6.6 years

Summary and Changes in Stock Options Outstanding


	2017					2016					2015
	Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price		Options			Weighted Average Exercise Price
Outstanding at January 1		6,112		$	20.01		5,507		$	15.63		5,750		$	9.31
Granted		1,807			46.55		1,077			40.19		1,159			37.21
Exercised		(1,353	)		10.41		(341	)		7.60		(1,315	)		5.01
Canceled		(210	)		43.05		(131	)		34.35		(87	)		46.08

Outstanding at December 31		6,356		$	28.83		6,112		$	20.01		5,507		$	15.63

Summary and Changes in Restricted Stock Units Outstanding


	2017					2016					2015
	Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit		Number of Units			Weighted Average Grant Date Fair Value per Unit
Outstanding at January 1		883		$	29.33		910		$	24.23		669		$	15.01
Granted		588			47.21		326			36.73		448			33.62
Cancelled		(41	)		40.62		(69	)		32.50		(16	)		20.83
Converted into common shares		(350	)		24.19		(284	)		20.71		(191	)		14.24

Outstanding at December 31		1,080		$	40.30		883		$	29.33		910		$	24.23

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Components of Deferred Tax Assets

Amounts are shown as of December 31 as of each respective year (in thousands):


	2017			2016
Deferred tax assets:
Net operating losses	$	238,500		$	309,100
Research and development credits		47,500			38,800
Capitalized research and development		47,500			80,200
Share-based compensation expense		14,600			17,400
Deferred revenue		2,800			4,300
Deferred gain on sales leaseback		2,100			3,800
Intangibles		1,700			4,800
Cease-use expense		—			300
Fixed assets		—			400
Other		8,000			4,400

Total deferred tax assets		362,700			463,500
Deferred tax liabilities:
Convertible debt		(31,300	)		—
Fixed assets		(500	)		—

Total deferred tax liabilities		(31,800	)		—

Net of deferred tax assets and liabilities		330,900			463,500
Valuation allowance		(330,900	)		(463,500	)

Net deferred tax assets	$	—		$	—

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 at December 31, 2017, 2016 and 2015, due to the following (in thousands):


	2017			2016			2015
Federal income taxes at 35%	$	(49,889	)	$	(49,383	)	$	(31,126	)
State income tax, net of Federal benefit		(4,013	)		2			2
Tax effect on non-deductible expenses		433			(321	)		172
Share-based compensation expense		(19,589	)		(5,077	)		201
Officer compensation		2,163			—			—
Change in tax rate		154,415			—			10,773
Expired tax attributes		2,998			6,708			5,594
Research credits		(8,352	)		(6,511	)		(6,638	)
Change in valuation allowance		(79,966	)		53,414			15,029
Uncertain tax positions		2,756			957			5,940
Other		(956	)		211			53

	$	—		$	—		$	—

The following table summarizes the activity related to our unrecognized tax benefits (in thousands):


	2017		2016			2015
Balance as of the beginning of the year	$	34,112	$	33,074		$	23,854
Increases related to prior year tax positions		—		260			6,636
Increases related to current year tax positions		3,291		2,211			2,584
Expiration of the statute of limitations for the assessment of taxes		—		(1,433	)		—

Balance as of the end of the year	$	37,403	$	34,112		$	33,074

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Results of Operations

The following is a summary of the quarterly results of the Company for the years ended December 31, 2017 and 2016 (unaudited, in thousands, except for per share data):


	Year Ended December 31,												Year Ended December 31
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter			Year Ended December 31
2016:
Revenues	$	15,000		$	—		$	—		$	—		$	15,000
Operating expenses		35,857			41,828			38,436			46,251			162,372
Net loss		(19,264	)		(40,280	)		(36,887	)		(44,659	)		(141,090	)
Net loss per share:
Basic and Diluted	$	(0.22	)	$	(0.46	)	$	(0.43	)	$	(0.51	)	$	(1.63	)
Shares used in the calculation of net loss per share:
Basic and Diluted		86,497			86,694			86,784			86,874			86,713
2017:
Revenues	$	—		$	6,335		$	60,774		$	94,517		$	161,626
Operating expenses		79,932			63,603			66,769			82,683			292,987
Net (loss) income		(78,326	)		(59,985	)		(11,125	)		6,894			(142,542	)
Net (loss) income per share:
Basic	$	(0.90	)	$	(0.68	)	$	(0.13	)	$	0.08		$	(1.62	)
Diluted	$	(0.90	)	$	(0.68	)	$	(0.13	)	$	0.07		$	(1.62	)
Shares used in the calculation of net (loss) income per share:
Basic		87,283			88,063			88,325			88,665			88,089
Diluted		87,283			88,063			88,325			92,659			88,089

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) shares in Millions		12 Months Ended
	May 02, 2017 USD ($) shares	Dec. 31, 2017 USD ($) Subsidiary Agreement shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of subsidiary wholly-owned by company \| Subsidiary		2
Investment income, net		$ 6,238,000	$ 2,838,000	$ 1,928,000
Convertible senior notes principal amount		$ 517,500,000
Number of collaboration agreements \| Agreement		2
2.25% Convertible Senior Notes due 2024
Organization And Summary Of Significant Accounting Policies [Line Items]
Convertible senior notes		7 years
Fair value of convertible senior note as percentage of principal amount		128.00%
Common share equivalents excluded from computation of earnings per share \| shares	6.8
Convertible senior notes principal amount	$ 517,500,000
Restricted Stock Units and Employee Options
Organization And Summary Of Significant Accounting Policies [Line Items]
Common share equivalents excluded from computation of earnings per share \| shares		3.4	3.8	4.1
Stock Options
Organization And Summary Of Significant Accounting Policies [Line Items]
Common share equivalents excluded from computation of earnings per share \| shares		0.4	0.4	0.1
Ingrezza
Organization And Summary Of Significant Accounting Policies [Line Items]
Advertising costs		$ 10,100,000
Prepaid expenses, advertising costs		$ 0
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average estimated useful life of equipment		3 years
Requisite service period of award		3 years
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average estimated useful life of equipment		7 years
Requisite service period of award		4 years

Significant Collaborative Research and Development Agreements - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mitsubishi Tanabe
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Up-front license fees				$ 30,000,000
Collaborative agreement maximum additional payment to receive				85,000,000
Patent rights period		The longer of ten years or the life of the related patent rights.
Clinical trial cost				12,000,000
Collaborative arrangement right description		Under the terms of the Company’s agreement with Mitsubishi Tanabe, the collaboration effort between the parties to advance INGREZZA towards commercialization in Japan and other select Asian markets is governed by a joint steering committee and joint development committee with representatives from both the Company and Mitsubishi Tanabe. There are no performance, cancellation, termination or refund provisions in the agreement that would have a material financial consequence to the Company. The Company does not directly control when event-based payments will be achieved or when royalty payments will begin. Mitsubishi Tanabe may terminate the agreement at its discretion upon 180 days’ written notice to the Company. In such event, all INGREZZA product rights for Japan and other select Asian markets would revert to the Company.
Collaboration termination notice period		180 days
Revenues recognized under collaboration agreement		$ 15,000,000	$ 0	19,800,000
Deferred revenues under collaboration				10,200,000
AbbVie
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Up-front license fees	$ 75,000,000
Patent rights period		Ten years or the life of the related patent rights.
Collaborative arrangement right description		The Company will be entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights.
Collaboration termination notice period		180 days
Revenues recognized under collaboration agreement		$ 30,000,000	$ 15,000,000	$ 0
Amount remains outstanding under collaboration agreement		455,000,000
AbbVie \| Development and Regulatory Milestone Payments
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement maximum additional payment to receive		480,000,000
Collaborative agreement payment received		75,000,000
AbbVie \| Commercial Milestone Payments
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement maximum additional payment to receive		$ 50,000,000

Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Investments	$ 508,578	$ 267,573
Certificates of deposit
Schedule of Investments [Line Items]
Investments	0	960
Commercial paper
Schedule of Investments [Line Items]
Investments	75,362	49,245
Corporate debt securities
Schedule of Investments [Line Items]
Investments	414,815	204,436
Domestic and foreign government agencies debt securities
Schedule of Investments [Line Items]
Investments	$ 18,401	$ 12,932

Summary of Investments Classified as Available-For-Sale Securities (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Schedule of Available-for-sale Securities [Line Items]

Aggregate Estimated Fair Value

$ 508,578

$ 267,573

Certificates of deposit

Schedule of Available-for-sale Securities [Line Items]

Aggregate Estimated Fair Value

960

Commercial paper

Schedule of Available-for-sale Securities [Line Items]

Aggregate Estimated Fair Value

75,362

49,245

Corporate debt securities

Schedule of Available-for-sale Securities [Line Items]

Aggregate Estimated Fair Value

414,815

204,436

Domestic and foreign government agencies debt securities

Schedule of Available-for-sale Securities [Line Items]

Aggregate Estimated Fair Value

18,401

12,932

Short-term investments

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

261,675

224,236

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(459)

(159)

Aggregate Estimated Fair Value

261,217

224,083

Short-term investments | Certificates of deposit

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

960

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

Aggregate Estimated Fair Value

$ 960

Short-term investments | Certificates of deposit | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Short-term investments | Commercial paper

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

75,396

$ 49,280

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(35)

(38)

Aggregate Estimated Fair Value

$ 75,362

$ 49,245

Short-term investments | Commercial paper | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Short-term investments | Corporate debt securities

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

$ 178,776

$ 168,548

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(400)

(117)

Aggregate Estimated Fair Value

$ 178,376

$ 168,434

Short-term investments | Corporate debt securities | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Short-term investments | Domestic and foreign government agencies debt securities

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

$ 7,503

$ 5,448

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(24)

(4)

Aggregate Estimated Fair Value

$ 7,479

$ 5,444

Short-term investments | Domestic and foreign government agencies debt securities | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Long-term investments

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

$ 248,753

$ 43,655

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(1,392)

(165)

Aggregate Estimated Fair Value

247,361

43,490

Long-term investments | Corporate debt securities

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

237,749

36,149

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(1,310)

(147)

Aggregate Estimated Fair Value

$ 236,439

$ 36,002

Long-term investments | Corporate debt securities | Minimum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Long-term investments | Corporate debt securities | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

2 years

Long-term investments | Domestic and foreign government agencies debt securities

Schedule of Available-for-sale Securities [Line Items]

Amortized Cost

$ 11,004

$ 7,506

Gross Unrealized Gains

^[1]

Gross Unrealized Losses

^[1]

(82)

(18)

Aggregate Estimated Fair Value

$ 10,922

$ 7,488

Long-term investments | Domestic and foreign government agencies debt securities | Minimum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

1 year

Long-term investments | Domestic and foreign government agencies debt securities | Maximum

Schedule of Available-for-sale Securities [Line Items]

Available for sale securities contractual maturity

2 years

[1]	Unrealized gains and losses are included in other comprehensive loss.

Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	$ 460,252	$ 241,956
Less Than 12 Months, Unrealized Losses	(1,777)	(321)
12 Months or Greater, Estimated Fair Value	35,566	9,144
12 Months or Greater, Unrealized Losses	(74)	(3)
Total Estimated Fair Value	495,818	251,100
Total Unrealized Losses	(1,851)	(324)
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	62,602	43,781
Less Than 12 Months, Unrealized Losses	(35)	(38)
12 Months or Greater, Estimated Fair Value	0	0
12 Months or Greater, Unrealized Losses	0	0
Total Estimated Fair Value	62,602	43,781
Total Unrealized Losses	(35)	(38)
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	386,728	185,243
Less Than 12 Months, Unrealized Losses	(1,660)	(261)
12 Months or Greater, Estimated Fair Value	28,087	9,144
12 Months or Greater, Unrealized Losses	(50)	(3)
Total Estimated Fair Value	414,815	194,387
Total Unrealized Losses	(1,710)	(264)
Domestic and foreign government agencies debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	10,922	12,932
Less Than 12 Months, Unrealized Losses	(82)	(22)
12 Months or Greater, Estimated Fair Value	7,479	0
12 Months or Greater, Unrealized Losses	(24)	0
Total Estimated Fair Value	18,401	12,932
Total Unrealized Losses	$ (106)	$ (22)

Fair Value Measurements - Additional Information (Detail) $ in Millions	Dec. 31, 2017 USD ($)
2.25% Convertible Senior Notes due 2024 \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument fair value	$ 662.1

Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment	$ 38,391	$ 32,221
Less accumulated depreciation	(27,580)	(25,950)
Property and equipment, net	10,811	6,271
Tenant improvements
Property, Plant and Equipment [Line Items]
Property and equipment	2,019	1,530
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	1,303	942
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	$ 35,069	$ 29,749

Property and Equipment - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation	$ 2,400,000	$ 1,500,000	$ 1,000,000
Gain on disposal of capital equipment	$ 7,000	$ 8,000	$ 9,000

Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued employee related costs	$ 24,901	$ 9,559
Accounts payable	5,648	5,085
Accrued development costs	4,799	5,543
Other accrued liabilities	18,172	5,995
Accounts payable and accrued liabilities	$ 53,520	$ 26,182

Commitments and Contingencies - Additional Information (Detail) ft² in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2007 USD ($) Building	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) ft² RenewalOptions Lease_Agreements	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2008 USD ($)
Commitment And Contingencies [Line Items]
Sale of facility and associated real property	$ 109.0
Mortgage debt retired	47.7
Cash received net of transaction costs and debt retirement	$ 61.0
Leaseback transaction lease period	12 years
Number of building leased \| Building	2
Net deferred gain on real estate sale			$ 8.8			$ 39.1
Deferred gain recognized on real estate sale			$ 2.1	$ 3.4	$ 3.3
Lease expiration year			2029
Percentage of management fee included in the base annual rent			3.50%
Letter of credit			$ 3.0
Lease extension period			10 years
Number of times to renew the lease contract \| RenewalOptions			2
Lease security deposit			$ 4.7
Subleased area \| ft²			16
Rent expense			$ 5.9	6.0	$ 6.0
Lease expiration year			2029
Milestone payables			$ 132.0
Minimum
Commitment And Contingencies [Line Items]
Lease cancellation, notice period			0 days
Maximum
Commitment And Contingencies [Line Items]
Lease cancellation, notice period			180 days
Royalty, rate			5.00%
Scenario, Forecast
Commitment And Contingencies [Line Items]
Rental income from sublease agreement		$ 0.1
Sublease
Commitment And Contingencies [Line Items]
Number of sublease agreements \| Lease_Agreements			1
Reversal of cease use expense			$ 0.5	$ 0.8
Second Sublease
Commitment And Contingencies [Line Items]
Lease expiration date			2018-03
Amended Lease Term
Commitment And Contingencies [Line Items]
Lease expiration date			Dec. 31, 2029
Percentage reduction in base rental			8.00%
Tenant improvement allowances			$ 13.1
Lease security deposit			$ 3.0

Changes to Accrued Cease-Use Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 853	$ 1,983
Change in estimate	(544)	(830)
Payments	(247)	(300)
Ending balance	$ 62	$ 853

Estimated Future Annual Minimum Lease Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 7,368
2019	7,589
2020	7,844
2021	8,079
2022 and thereafter	74,000
Total future minimum lease payments	$ 104,880

Convertible Senior Notes - Additional Information (Detail) $ / shares in Units, $ in Thousands		12 Months Ended
	May 02, 2017 USD ($)	Dec. 31, 2017 USD ($) d $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Convertible senior notes principal amount		$ 517,500
Proceeds from Senior Convertible Notes		$ 502,781	$ 0	$ 0
2.25% Convertible Senior Notes due 2024
Debt Instrument [Line Items]
Convertible senior notes principal amount	$ 517,500
Convertible senior notes interest percentage	2.25%
Convertible senior notes convertible latest date		May 15, 2024
Convertible senior notes interest rate	2.25%
Proceeds from Senior Convertible Notes	$ 502,800
Threshold common stock trading days \| d		20
Threshold consecutive common stock trading days \| d		30
Threshold percentage of common stock price trigger		130.00%
Minimum percentage of common stock price trigger		98.00%
Conversion Observation Period		25 days
Convertible senior notes convertible in to shares		0.00131711
Convertible senior notes conversion price \| $ / shares		$ 75.92
Market Price of Common stock \| $ / shares		$ 53.28
Convertible senior note premium		42.50%
Convertible senior notes redemption rate		100.00%
Convertible senior note carrying value of the liability component		$ 368,300
Convertible senior note assumed borrowing rate		7.50%
Convertible senior note carrying value of the equity component		$ 149,200
Convertible senior notes		7 years
Transaction cost related to issuance of convertible senior note		$ 14,700

Convertible Senior Notes - Debt Net of Discount and Deferred Financing (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Principal	$ 517,500
Deferred financing costs	(9,652)
Debt discount, net	(138,230)
Net carrying amount	$ 369,618	$ 0

Share-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding	6,356,000	6,112,000	5,507,000	5,750,000
Number of common stock available for future grant	6,300,000
Tax benefits recognized in the consolidated statements of cash flows	$ 0
Weighted-average fair values of options granted	$ 25.11	$ 21.49	$ 23.24
Weighted average remaining contractual term for options outstanding	6 years 8 months 12 days
Share-based compensation expense	$ 42,522,000	$ 28,464,000	$ 28,392,000
Number of stock options exercisable	4,200,000
Stock options exercisable, weighted average exercise price	$ 21.22
Stock options exercisable, weighted-average remaining contractual term	5 years 8 months 12 days
Stock options exercised in period intrinsic value	$ 61,400,000	13,200,000	43,600,000
Stock options intrinsic value of options outstanding	309,900,000
Stock options intrinsic value of options exercisable	234,900,000
Cash received from stock option exercises	$ 13,900,000	$ 2,400,000	$ 6,300,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, term	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, term	4 years
Share-based compensation, contractual term	10 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted	588,000	326,000	448,000
Share-based compensation expense	$ 13,900,000	$ 8,300,000	$ 6,000,000
Unrecognized compensation cost	$ 30,000,000
Stock vesting period	2 years 8 months 12 days
Total intrinsic value vested in period	$ 14,900,000	12,200,000	5,700,000
Intrinsic value outstanding	$ 83,800,000
Restricted Stock Units (RSUs) \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	4 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 28,200,000	$ 18,400,000	$ 13,600,000
Unrecognized compensation cost	$ 44,000,000
Stock vesting period	2 years 8 months 12 days
Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	3 years
Share-based compensation, term	7 years
Stock Options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	4 years
Share-based compensation, term	10 years
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted	0	230,000	50,000
Share-based compensation expense	$ 400,000	$ 1,800,000	$ 8,800,000
Unrecognized compensation cost	7,500,000
Intrinsic value outstanding	$ 16,300,000
Performance-based RSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	4 years
Performance-based RSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	5 years
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted	410,000	0	120,000
Stock vesting period	4 years		4 years
Stock options outstanding	400,000
Employees \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period	3 years		3 years
Restricted stock units granted	12,500	0	50,000
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock authorized for issuance					17,000,000
Share Based Compensation Arrangement Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock authorized for issuance	14,100,000
PRSUs Converted into Common Shares \| Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value outstanding	$ 8,800,000	$ 0	$ 14,900,000

Compensation Cost Related to Share-Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 42,522	$ 28,464	$ 28,392
Sales, General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	27,951	16,770	15,281
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 14,571	$ 11,694	$ 13,111

Weighted-Average Assumptions for Stock Option Grants using Black-Scholes Option-Pricing Model (Detail) - Stock Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.00%	1.40%	1.70%
Expected volatility of common stock	58.00%	60.00%	66.00%
Dividend yield	0.00%	0.00%	0.00%
Expected option term	5 years 8 months 12 days	5 years 7 months 6 days	6 years 7 months 6 days

Summary and Changes in Stock Options Outstanding (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding, Beginning Balance	6,112	5,507	5,750
Granted	1,807	1,077	1,159
Exercised	(1,353)	(341)	(1,315)
Canceled	(210)	(131)	(87)
Outstanding, Ending Balance	6,356	6,112	5,507
Weighted average exercise price
Outstanding, Beginning Balance	$ 20.01	$ 15.63	$ 9.31
Granted	46.55	40.19	37.21
Exercised	10.41	7.60	5.01
Canceled	43.05	34.35	46.08
Outstanding, Ending Balance	$ 28.83	$ 20.01	$ 15.63

Summary and Changes in Restricted Stock Units Outstanding (Detail) - Restricted Stock Units (RSUs) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted stock units
Outstanding, Beginning Balance	883	910	669
Granted	588	326	448
Cancelled	(41)	(69)	(16)
Converted into common shares	(350)	(284)	(191)
Outstanding Ending Balance	1,080	883	910
Weighted average grant date fair value
Outstanding Beginning Balance	$ 29.33	$ 24.23	$ 15.01
Granted	47.21	36.73	33.62
Cancelled	40.62	32.50	20.83
Converted into common shares	24.19	20.71	14.24
Outstanding Ending Balance	$ 40.30	$ 29.33	$ 24.23

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Proceeds from common stock issuance	$ 270,700	$ 13,865	$ 2,390	$ 276,992
Common Stock
Class of Stock [Line Items]
Common stock issued	8,000			7,986
Common stock, offering price	$ 36.00

BIAL Agreement - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017
License Agreement [Line Items]
Milestone payables		$ 132
B I A L
License Agreement [Line Items]
License agreement date		Feb. 09, 2017
Up-front license fees	$ (30)
B I A L \| Regulatory Approval and Net Sales Milestones
License Agreement [Line Items]
Milestone payables	115
B I A L \| Regulatory and Clinical Results and FDA Acceptance Milestones
License Agreement [Line Items]
Milestone payables	$ 20

Concentration Risk - Additional Information (Detail) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2017 Customer
Sales Revenue, Goods, Net
Concentration Risk [Line Items]
Number of customers	3
Percentage of product revenue	99.00%
Accounts Receivable
Concentration Risk [Line Items]
Number of customers	3

Income Taxes - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Deferred tax assets		$ 362,700,000	$ 463,500,000
Deferred tax liabilities		31,800,000	0
Research and development tax credit carry forwards		$ 47,500,000	$ 38,800,000
Corporate tax rate		35.00%	35.00%	35.00%
Deferred tax assets, valuation allowance		$ 330,900,000	$ 463,500,000
Percentage of uncertain tax positions likelihood of being sustained		50.00%
Accrual interest or penalties		$ 0	0
Increases related to current year tax positions		3,291,000	$ 2,211,000	$ 2,584,000
Unrecognized tax benefits that would affect effective tax rate		30,700,000
Subsequent Event
Income Taxes [Line Items]
Corporate tax rate	21.00%
Federal
Income Taxes [Line Items]
Operating loss carry forward, net		$ 978,700,000
Operating loss carry forward beginning expiration year		2021
Research and development tax credit carry forwards		$ 48,200,000
Alternative Minimum Tax credit carry forwards		$ 100,000
Federal \| R&D
Income Taxes [Line Items]
Tax credit carry forwards beginning expiration year		2018
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carry forward, net		$ 535,300,000
Research and development tax credit carry forwards		$ 34,600,000
State and Local Jurisdiction \| California
Income Taxes [Line Items]
Operating loss carry forward beginning expiration year		2018
State and Local Jurisdiction \| Other States
Income Taxes [Line Items]
Operating loss carry forward beginning expiration year		2027

Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating losses	$ 238,500	$ 309,100
Research and development credits	47,500	38,800
Capitalized research and development	47,500	80,200
Share-based compensation expense	14,600	17,400
Deferred revenue	2,800	4,300
Deferred gain on sales leaseback	2,100	3,800
Intangibles	1,700	4,800
Cease-use expense	0	300
Fixed assets	0	400
Other	8,000	4,400
Total deferred tax assets	362,700	463,500
Deferred tax liabilities:
Convertible debt	(31,300)	0
Fixed assets	(500)	0
Total deferred tax liabilities	(31,800)	0
Net of deferred tax assets and liabilities	330,900	463,500
Valuation allowance	(330,900)	(463,500)
Net deferred tax assets	$ 0	$ 0

Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income taxes at 35%	$ (49,889)	$ (49,383)	$ (31,126)
State income tax, net of Federal benefit	(4,013)	2	2
Tax effect on non-deductible expenses	433	(321)	172
Share-based compensation expense	(19,589)	(5,077)	201
Officer compensation	2,163	0	0
Change in tax rate	154,415	0	10,773
Expired tax attributes	2,998	6,708	5,594
Research credits	(8,352)	(6,511)	(6,638)
Change in valuation allowance	(79,966)	53,414	15,029
Uncertain tax positions	2,756	957	5,940
Other	(956)	211	53
Income Tax Expense (Benefit), Total	$ 0	$ 0	$ 0

Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income taxes, rate	35.00%	35.00%	35.00%

Activity Related to Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefit beginning Balance	$ 34,112	$ 33,074	$ 23,854
Increases related to prior year tax positions	0	260	6,636
Increases related to current year tax positions	3,291	2,211	2,584
Expiration of the statute of limitations for the assessment of taxes	0	(1,433)	0
Unrecognized tax benefit ending Balance	$ 37,403	$ 34,112	$ 33,074

Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined contribution plan, maximum employee contribution percentage	60.00%
Defined contribution plan, employer contribution amount	$ 1.1	$ 0.6	$ 0.4

Summary of Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 94,517	$ 60,774	$ 6,335	$ 0	$ 0	$ 0	$ 0	$ 15,000	$ 161,626	$ 15,000	$ 19,769
Operating expenses	82,683	66,769	63,603	79,932	46,251	38,436	41,828	35,857	292,987	162,372	113,971
Net (loss) income	$ 6,894	$ (11,125)	$ (59,985)	$ (78,326)	$ (44,659)	$ (36,887)	$ (40,280)	$ (19,264)	$ (142,542)	$ (141,090)	$ (88,929)
Net (loss) income per share:
Basic	$ 0.08	$ (0.13)	$ (0.68)	$ (0.90)					$ (1.62)	$ (1.63)	$ (1.05)
Diluted	$ 0.07	$ (0.13)	$ (0.68)	$ (0.90)					$ (1.62)	(1.63)	$ (1.05)
Net loss per share:
Basic and Diluted					$ (0.51)	$ (0.43)	$ (0.46)	$ (0.22)		$ (1.63)
Shares used in the calculation of net (loss) income per share:
Basic	88,665	88,325	88,063	87,283					88,089	86,713	84,496
Diluted	92,659	88,325	88,063	87,283					88,089	86,713	84,496
Shares used in the calculation of net loss per share:
Basic and Diluted					86,874	86,784	86,694	86,497		86,713

Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	$ 508.6	$ 267.6
Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	516.0	307.3
Short-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	170.2	73.6
Short-term investments \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value		1.0
Short-term investments \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	159.9	49.2
Short-term investments \| Domestic and foreign government agencies debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	7.5	5.4
Short-term investments \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	178.4	178.1
Long-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1.5
Long-term investments \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	3.0	4.9
Long-term investments \| Domestic and foreign government agencies debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	10.9	7.5
Long-term investments \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	236.4	36.0
Investments Including Cash Equivalents And Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	767.8	355.7
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	259.2	88.1
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.1	1.0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	170.2	74.6
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	170.2	73.6
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis		1.0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| 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
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| Domestic and foreign government agencies 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
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Short-term investments \| 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
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	1.5
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	3.0	4.9
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| Domestic and foreign government agencies 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
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Long-term investments \| 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
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Investments Including Cash Equivalents And Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	174.7	79.5
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	174.6	78.5
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	508.5	266.6
Significant Other Observable Inputs (Level 2) \| Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	345.8	232.7
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Significant Other Observable Inputs (Level 2) \| Short-term investments \| 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
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	159.9	49.2
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Domestic and foreign government agencies debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	7.5	5.4
Significant Other Observable Inputs (Level 2) \| Short-term investments \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	178.4	178.1
Significant Other Observable Inputs (Level 2) \| Long-term investments \| 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
Significant Other Observable Inputs (Level 2) \| Long-term investments \| Domestic and foreign government agencies debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	10.9	7.5
Significant Other Observable Inputs (Level 2) \| Long-term investments \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	236.4	36.0
Significant Other Observable Inputs (Level 2) \| Investments Including Cash Equivalents And Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	593.1	276.2
Significant Other Observable Inputs (Level 2) \| Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	84.6	9.6
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Significant Unobservable Inputs (Level 3) \| Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Significant Unobservable Inputs (Level 3) \| Short-term investments \| Cash and money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets on recurring basis	0.0	0.0
Significant Unobservable Inputs (Level 3) \| Short-term investments \| 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
Significant Unobservable Inputs (Level 3) \| Short-term investments \| 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
Significant Unobservable Inputs (Level 3) \| Short-term investments \| Domestic and foreign government agencies 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
Significant Unobservable Inputs (Level 3) \| Short-term investments \| 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
Significant Unobservable Inputs (Level 3) \| Long-term investments \| 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
Significant Unobservable Inputs (Level 3) \| Long-term investments \| Domestic and foreign government agencies 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
Significant Unobservable Inputs (Level 3) \| Long-term investments \| 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
Significant Unobservable Inputs (Level 3) \| Investments Including Cash Equivalents And 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
Significant Unobservable Inputs (Level 3) \| Cash and 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