| SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) | 12 Months Ended |
| Dec. 31, 2016 |
| Accounting Policies [Abstract] | |
| Basis of Presentation and Principles of Consolidation | Basis of Presentation and Principles of Consolidation The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America, or GAAP, and in accordance with the rules and regulations of the Securities and Exchange Commission, or SEC. The accounts of wholly owned subsidiaries are included in the consolidated financial statements. All intercompany balances and transactions have been eliminated in consolidation. Certain reclassifications were made to conform to the current presentation. |
| Use of Estimates | Use of Estimates The preparation of financial statements in conformity with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, including disclosure of contingent assets and contingent liabilities, at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Estimates are used for, among other things, revenue recognition, inventory costs, impairments of goodwill and long-lived assets, liabilities and accruals, stock-based compensation and the valuation of deferred tax assets. The Company’s critical accounting policies are those that are both most important to the Company’s consolidated financial condition and results of operations and require the most difficult, subjective or complex judgments on the part of management in their application, often as a result of the need to make estimates about the effect of matters that are inherently uncertain. Because of the uncertainty of factors surrounding the estimates or judgments used in the preparation of the consolidated financial statements, actual results could differ from these estimates. |
| Liquidity | Liquidity Management believes that the Company’s existing cash and cash equivalents, short-term investments and cash flows generated from product sales will be sufficient to enable the Company to meet its planned operating expenses, capital expenditure requirements, payment of the principal on any conversions of the Company’s convertible senior notes and to service its indebtedness at least through March 1, 2018 . However, changing circumstances may cause the Company to expend cash significantly faster than currently anticipated, and the Company may need to spend more cash than currently expected because of circumstances beyond its control. See Note 8, Debt, for further discussion of the Company’s convertible senior notes and conversion elections. The Company expects to continue to incur substantial additional expenditures as it continues to commercialize EXPAREL, develops and seeks regulatory approval for its product candidates, and expands its manufacturing facilities for EXPAREL and its other product candidates, including costs associated with certain technical transfer activities and construction of two dedicated manufacturing suites in England. |
| Revenue Recognition | Revenue Recognition The Company’s principal sources of revenue include (i) sales of EXPAREL in the United States, or US, (ii) sales of DepoCyt(e) to our commercial partners within the US and the European Union, or EU, (iii) royalties based on sales by commercial partners of DepoCyt(e) and (iv) license fees and milestone payments. The Company recognizes revenue when there is persuasive evidence that an arrangement exists, title has passed, collection is reasonably assured and the price is fixed or determinable. Net Product Sales The Company sells EXPAREL through a drop-ship program under which orders are processed through wholesalers based on orders of the product placed by end users which include hospitals, ambulatory surgery centers and doctors. EXPAREL is delivered directly to the end-user without the wholesaler ever taking physical possession of the product. The Company records revenue at the time the product is delivered to the end user. The Company also recognizes revenue from DepoCyt(e) and other product sales upon shipment. Prior to the shipment of manufactured products, the Company conducts initial product release and stability testing in accordance with current Good Manufacturing Practices. Revenues from sales of products are recorded net of returns allowances, prompt payment discounts, wholesaler service fees and volume rebates and chargebacks. The calculation of some of these items requires management to make estimates based on sales data, contract terms, inventory data and other related information which may become known in the future. The Company reviews the adequacy of its provisions on a quarterly basis. Returns Allowances The Company allows customers to return product that is damaged or received in error. In addition, the Company allows EXPAREL to be returned beginning six months prior to, and 12 months following product expiration. The Company estimates its sales return reserve based on its historical return rates, which management believes is the best estimate of the anticipated product to be returned. The returns reserve is recorded at the time of sale as a reduction to gross product sales and an increase in accrued expenses. The Company’s commercial partners can return DepoCyt(e) within contractually specified timeframes if the product does not meet the applicable inspection tests. The Company estimates its returns reserve based on its experience with historical return rates. Historically, the Company’s DepoCyt(e) returns have not been material. Prompt Payment Discounts The prompt payment reserve is based upon discounts offered to wholesalers as an incentive to meet certain payment terms. The Company accrues discounts to wholesalers based on contractual terms of agreements and historical experience. The Company accounts for these discounts at the time of sale as a reduction to gross product sales and a reduction to accounts receivable. Wholesaler Service Fees The Company’s customers include major and regional wholesalers with whom the Company has contracted a fee for service based on a percentage of gross product sales. This fee for service is recorded as a reduction to gross product sales and an increase to accrued expenses at the time of sale, and is recorded based on the contracted percentage. Volume Rebates and Chargebacks Volume rebates and chargeback reserves are based upon contracted discounts and promotional offers the Company provides to certain end users such as members of group purchasing organizations. Volume rebates are recorded at the time of sale as a reduction to gross product sales and an increase in accrued expenses. Chargeback reserves are recorded at the time of sale as a reduction to gross product sales and a reduction to accounts receivable. The following table provides a summary of activity with respect to the Company’s accrued rebates and chargebacks, returns, wholesaler service fees and prompt pay discounts for the years ended December 31, 2016 , 2015 and 2014 (in thousands): Returns Allowances Prompt Payment Discounts Wholesaler Service Fees Volume Rebates and Chargebacks Total Balance at December 31, 2013 $ 897 $ 313 $ 266 $ 402 $ 1,878 Provision 829 3,833 2,780 881 8,323 Payments/credits (167 ) (3,571 ) (2,458 ) (962 ) (7,158 ) Balance at December 31, 2014 1,559 575 588 321 3,043 Provision 339 4,905 3,482 2,020 10,746 Payments/credits (165 ) (4,855 ) (3,325 ) (1,544 ) (9,889 ) Balance at December 31, 2015 1,733 625 745 797 3,900 Provision 694 5,448 4,118 2,611 12,871 Payments/credits (1,081 ) (5,478 ) (4,128 ) (2,284 ) (12,971 ) Balance at December 31, 2016 $ 1,346 $ 595 $ 735 $ 1,124 $ 3,800 Royalty Revenue The Company recognizes revenue from royalties based on sales of its commercial partners’ net sales of DepoCyt(e) and sales of bupivacaine liposome injectable suspension product to serve animal health indications. Royalties are recognized as earned in accordance with contract terms when they can be reasonably estimated and collection is reasonably assured. Based on historical product sales, royalty receipts and other relevant information, the Company accrues royalty revenue each quarter. Collaborative Licensing and Milestone Revenue The Company recognizes revenues from non-refundable up-front license fees received under collaboration agreements ratably over the performance period as determined under the agreement (estimated development period in the case of development agreements, and contract period or longest patent life in the case of supply and distribution agreements). If the estimated performance period is subsequently modified, the Company will modify the period over which the up-front license fee is recognized accordingly on a prospective basis. Upon notification of a termination of a collaboration agreement, any remaining non-refundable license fees received by the Company, which had been deferred, are recognized over the remaining contractual term. If the termination is immediate and no additional services are to be performed, the deferred revenue is generally recognized in full. All such recognized revenues are included in collaborative licensing and milestone revenue in the Company’s consolidated statements of operations. The Company recognizes revenue from milestone payments received under collaboration agreements when earned, provided that the milestone event is substantive, its achievability was not reasonably assured at the inception of the agreement, the Company has no further performance obligations relating to the event and collection is reasonably assured. If these criteria are not met, the Company recognizes milestone payments ratably over the remaining period of the Company’s performance obligations under the applicable agreements. |
| Concentration of Major Customers | Concentration of Major Customers The Company’s customers are national and regional wholesalers of pharmaceutical products as well as commercial, collaborative and licensing partners. The Company sells EXPAREL through a drop-ship program under which orders are processed through wholesalers (including AmerisourceBergen Health Corporation, Cardinal Health, Inc., and McKesson Drug Company), but shipments of the product are sent directly to individual accounts, such as hospitals, ambulatory surgery centers and individual doctors. The table below includes the percentage of revenue comprised by the three largest customers (i.e.(i.e.,wholesalers or commercial partners) in each year presented: Year Ended December 31, 2016 2015 2014 Largest customer 32 % 33 % 33 % Second largest customer 28 % 29 % 29 % Third largest customer 26 % 28 % 24 % 86 % 90 % 86 % Revenues from customers outside the US accounted for 1% , 2% and 2% of the Company’s revenue for the years ended December 31, 2016 , 2015 and 2014 , respectively. |
| Research and Development Expenses | Research and Development Expenses Research and development expenses consist of costs associated with products and processes being developed, and include related personnel expenses, laboratory supplies, active pharmaceutical ingredients, manufacturing supplies, facilities costs, preclinical and clinical trial costs and other outside service fees. The Company expenses research and development costs as incurred. A significant portion of the development activities are outsourced to third parties, including contract research organizations. In such cases, the Company may be required to estimate related service fees to be accrued. |
| Cash and Cash Equivalents | Cash and Cash Equivalents All highly-liquid investments with maturities of 90 days or less when purchased are considered cash equivalents. |
| Short-Term Investments | Short-Term and Long-Term Investments Short-term investments consist of asset-backed securities collateralized by credit card receivables, investment grade commercial paper and corporate bonds with initial maturities of greater than three months at the date of purchase, but less than one year. Long-term investments consist of corporate bonds with initial maturities greater than one year at the date of purchase. The Company determines the appropriate classification of its investments at the time of purchase and reevaluates such determination at each balance sheet date. The Company’s investment policy sets minimum credit quality criteria and maximum maturity limits on its investments to provide for preservation of capital, liquidity and a reasonable rate of return. Available-for-sale securities are recorded at fair value, based on current market valuations. Unrealized holding gains and losses on available-for-sale securities are excluded from net loss and are reported as a separate component of accumulated other comprehensive loss until realized. Realized gains and losses are included in interest income in the consolidated statements of operations and are derived using the specific identification method for determining the cost of the securities sold. |
| Inventories | Inventories Inventories consist of finished goods held for sale and distribution, raw materials and work in process. Inventories are stated at the lower of cost, which includes amounts related to material, labor and overhead, or market (net realizable) value and is determined using the first-in, first-out (“FIFO”) method. The Company periodically reviews its inventory to identify obsolete, slow-moving, or otherwise unsalable inventories, and establishes allowances for situations in which the cost of the inventory is not expected to be recovered. |
| Fixed Assets | Fixed Assets Fixed assets are recorded at cost, net of accumulated depreciation and amortization. The Company reviews its property, plant and equipment assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Depreciation of fixed assets is provided over their estimated useful lives on a straight-line basis. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the related remaining lease terms. Useful lives by asset category are as follows: Asset Category Useful Lives Computer equipment and software 1 to 3 years Office furniture and equipment 5 years Manufacturing and laboratory equipment 5 to 10 years |
| Asset Retirement Obligations | Asset Retirement Obligations The Company has contractual obligations stemming from certain of its lease agreements to return leased space to its original condition upon termination of the lease agreement. The Company records an asset retirement obligation, or ARO, along with a corresponding capital asset in an amount equal to the estimated fair value of the ARO. In subsequent periods, the Company records interest expense to accrete the ARO to full value. Each ARO capital asset is depreciated over the depreciable term of the associated asset. |
| Goodwill and Intangible Assets | Goodwill and Intangible Assets Intangible assets are recorded at cost, net of accumulated amortization. Amortization of intangible assets is provided over their estimated useful lives on a straight-line basis. Goodwill represents the excess of purchase price over fair value acquired in a business combination and is not amortized, but subject to impairment at least annually or when a triggering event occurs that could indicate a potential impairment. |
| Impairment of Long-Lived Assets | Impairment of Long-Lived Assets Management reviews long-lived assets, including fixed assets, for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. |
| Convertible Debt Transactions | Convertible Debt Transactions The Company separately accounts for the liability and equity components of convertible debt instruments by allocating the proceeds from the issuance between the liability component and the embedded conversion option, or equity component. This is done in accordance with accounting for convertible debt instruments that may be settled in cash (including partial cash settlement) upon conversion. The value of the equity component is calculated by first measuring the fair value of the liability component, using the interest rate of a similar liability that does not have a conversion feature, as of the issuance date. The difference between the initial proceeds from the convertible debt issuance and the fair value of the liability component is recorded as the carrying amount of the equity component. The Company recognizes the amortization of the resulting discount as part of interest expense in its consolidated statements of operations. Upon settlement of the convertible senior notes, the liability component is measured at fair value. The Company allocates a portion of the fair value of the total settlement consideration transferred to the extinguishment of the liability component equal to the fair value of that component immediately prior to the settlement. Any difference between the consideration attributed to the liability component and the net carrying amount of the liability component, including any unamortized debt issuance costs, is recognized as a gain or loss in the consolidated statements of operations. Any remaining consideration is allocated to the reacquisition of the equity component and is recognized as a reduction of additional paid-in capital. |
| Foreign Currencies | Foreign Currencies The Company receives payment from certain commercial partners relating to accounts receivable and royalties on DepoCyte ® in Euros. Gains and losses from foreign currency transactions are reflected in the consolidated statements of operations and were not significant in any period. All foreign currency receivables and payables are measured at the applicable exchange rate at the end of the reporting period. |
| Income Taxes | Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to basis differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. As of December 31, 2016 and 2015 , all deferred tax assets were fully offset by a valuation allowance because there is significant doubt regarding the Company’s ability to utilize such net deferred tax assets. The Company accrues interest and penalties, if any, on underpayment of income taxes related to unrecognized tax benefits as a component of income tax expense in its consolidated statements of operations. |
| Per Share Data | Per Share Data Basic net income (loss) per common share is computed by dividing net income (loss) available (attributable) to common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per common share is calculated by dividing net income (loss) available (attributable) to common stockholders as adjusted for the effect of dilutive securities, if any, by the weighted average number of common stock and dilutive common stock outstanding during the period. Potential common shares include the shares of common stock issuable upon the exercise of outstanding stock options and warrants, the vesting of restricted stock units, or RSUs, and the purchase of shares from the employee stock purchase plan (using the treasury stock method), as well as the conversion of the excess conversion value on the Company’s convertible senior notes. Potential common shares in the diluted net loss per share computation are excluded to the extent that they would be anti-dilutive. For periods where the Company reported a net loss, no potentially dilutive securities were included in the computation of diluted net loss per share. |
| Stock-Based Compensation | Stock-Based Compensation The Company’s stock-based compensation program includes grants of stock options and restricted stock units to employees, consultants, and non-employee directors in addition to the opportunity for employees to participate in an employee stock purchase plan. The expense associated with these programs is recognized in the Company’s consolidated statements of operations based on their fair values as they are earned under the applicable vesting terms or the length of an offering period. The valuation of stock options is an inherently subjective process, since market values are generally not available for long-term, non-transferable stock options. Accordingly, the Company uses an option pricing model to derive an estimated fair value. In calculating the estimated fair value of stock options granted, the Company uses the Black-Scholes option valuation model, or Black-Scholes model, which requires the consideration of the following variables for purposes of estimating fair value: • Expected term of the option • Expected volatility • Expected dividends • Risk-free interest rate Since its initial public offering, the Company utilizes its available historic volatility data combined with a publicly traded peer group’s historic volatility to determine expected volatility over the expected option term. The Company used an expected term based on its historical data from stock option exercises. In prior years the Company utilized the “simplified” method for “plain vanilla” options to estimate the expected term of stock option grants. Under that approach, the weighted average expected life was presumed to be the average of the vesting term and the contractual term of the option. The risk-free interest rate is based on the implied yield on United States Department of the Treasury zero coupon bonds for periods commensurate with the expected term of the options. The dividend yield on the Company’s common stock is estimated to be zero as the Company has not paid any dividends since inception, nor does it have any intention to do so in the foreseeable future. The Company estimates the level of award forfeitures expected to occur based on its historical data and records compensation cost only for those awards that are ultimately expected to vest. |
| Segment Reporting | Segment Reporting The Company operates in one reportable segment and, accordingly, no segment disclosures have been presented. |
| Recent Accounting Pronouncements | RECENT ACCOUNTING PRONOUNCEMENTS Recently Adopted In April 2015, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs , which requires debt issuance costs related to a recognized debt liability be presented on the balance sheet as a direct deduction from the carrying amount of the related debt liability instead of being presented as an asset. Debt disclosures will include the face amount of the debt liability and the effective interest rate. The update requires retrospective application and represents a change in accounting principle. The update is effective for fiscal years beginning after December 15, 2015. The Company adopted this standard on January 1, 2016. The Company applied the new guidance retrospectively to all prior periods presented in the financial statements to conform to the 2016 presentation. As a result, $1.9 million of debt issuance costs related to the Company’s convertible senior notes at December 31, 2015 were reclassified from other assets to a reduction in the carrying value of the Company’s convertible senior notes. Not Adopted as of December 31, 2016 In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , which requires that an entity recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to its customers. In order to achieve this core principle, an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when (or as) the entity satisfies a performance obligation. During the fiscal third quarter of 2015, the FASB approved a one year deferral to the effective date to be adopted by all public companies for all annual periods and interim reporting periods beginning after December 15, 2017. During 2016, the FASB issued additional guidance and clarification relating to identifying performance obligations, licensing, principal versus agent considerations, assessing collectability, presentation of sales taxes, noncash consideration and contract modifications and completed contracts at transition. These updates will replace existing revenue recognition guidance under GAAP when it becomes effective for the Company beginning January 1, 2018, and permits two methods of adoption: the full retrospective method, which requires the standard to be applied to each prior period presented, or the modified retrospective method, which requires the cumulative effect of adoption to be recognized as an adjustment to opening retained earnings in the period of adoption. While the Company is continuing to evaluate the impact of these updates on its consolidated financial statements, it does not expect the implementation of ASU 2014-09 and the subsequently issued related guidance to have a material impact on its consolidated financial statements. In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory . The standard requires entities to measure most inventory “at the lower of cost and net realizable value,” thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market (market in this context is defined as one of three different measures, one of which is net realizable value). The standard is effective for the Company prospectively beginning January 1, 2017. The adoption of ASU 2015-11 is not expected to have a material impact on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (ASC 842) . This update requires lessees to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous authoritative guidance. The lease liability will be equal to the present value of lease payments and the right-of-use asset will be based on the lease liability, subject to adjustment for items such as initial direct costs. For income statement purposes, the new standard retains a dual model similar to Accounting Standards Codification, or ASC, 840, requiring leases to be classified as either operating or financing. For lessees, operating leases will result in straight-line expense (similar to current accounting by lessees for operating leases under ASC 840) while financing leases will result in a front-loaded expense pattern (similar to current accounting by lessees for capital leases under ASC 840). This update also introduces new disclosure requirements for leasing arrangements. The standard is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those annual periods. Early adoption is permitted. The Company is evaluating the impact of ASU 2016-02 on its consolidated financial statements. Refer to Note 17, Commitments and Contingencies , for further discussion on the Company’s leases. In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . This update includes multiple provisions intended to simplify various aspects of the accounting for share-based payment transactions including accounting for excess tax benefits and tax deficiencies, classification of excess tax benefits in the statement of cash flows and accounting for award forfeitures. The update also removes the present requirement to delay recognition of an excess tax benefit until it reduces current taxes payable, instead, it is required to be recognized at the time of settlement, subject to normal valuation allowance considerations. This update became effective for the Company beginning January 1, 2017. The Company will elect an accounting policy change to record forfeitures as they occur rather than estimating forfeitures during each period and will record a charge of approximately $0.3 million to retained earnings as of January 1, 2017 related to the reversal of cumulative forfeiture estimates. The adoption of this standard also will result in the recognition of $29.3 million of previously unrecognized excess tax benefits in deferred tax assets, fully offset by a valuation allowance. All tax-related cash flows resulting from stock-based compensation, including the excess tax benefits related to the settlement of stock-based awards, will be classified as cash flows from operating activities on the Company’s consolidated statements of cash flows. Based on a preliminary assessment, the Company does not believe that any of the provisions in ASU 2016-09 will have a significant impact on its consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326) , which requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. Entities will now use forward-looking information to better form their credit loss estimates. This update also requires enhanced disclosures to help financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an entity’s portfolio. This ASU is effective for annual reporting periods beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the impact of ASU 2016-13 on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies existing guidance on how companies present and classify certain cash receipts and cash payments in the statement of cash flows by addressing specific cash flow issues in an effort to reduce diversity in practice, including guidance on debt prepayment or extinguishment costs and contingent consideration payments made after a business combination. This update is effective for annual reporting periods beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the impact of ASU 2016-15 on its consolidated financial statements. Other pronouncements issued by the FASB or other authoritative accounting standards groups with future effective dates are either not applicable or not significant to the consolidated financial statements of the Company. |
