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

Organization and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

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

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

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

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

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

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

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

Principles of Consolidation

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

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

Use of Estimates

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

Industry Segment and Geographic Information

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

Cash Equivalents

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

Accounts Receivable

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

Marketable Securities

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

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

Restricted Equity Securities

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

Fair Value of Financial Instruments

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

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

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

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

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

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

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

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

Inventory

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

Property and Equipment

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

Impairment of Long-Lived Assets

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

Revenue Recognition

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

Product Sales, Net

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

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

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

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

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

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

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

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

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

Collaboration Revenue

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

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

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

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

Concentration of Credit Risk

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

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

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

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

Cost of Sales

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

Research and Development Expenses

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

Asset Acquisitions

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

Advertising Expense

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

Share-Based Compensation

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

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

Net Income (Loss) Per Share

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

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

Recently Adopted Accounting Pronouncements

Recently Adopted Accounting Pronouncements.

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

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

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

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

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

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

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

Recently Issued Accounting Pronouncements

Recently Issued Accounting Pronouncements.

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

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