SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation These interim condensed 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 United States Securities and Exchange Commission (SEC), for interim reporting. Pursuant to these rules and regulations, certain information and footnote disclosures normally included in complete annual financial statements have been condensed or omitted. Therefore, these interim condensed consolidated financial statements should be read in conjunction with the audited annual consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. The condensed consolidated financial statements at September 30, 2021, and for the three and nine month periods ended September 30, 2021 and 2020, are unaudited, but include all adjustments (consisting of only normal recurring adjustments) which, in the opinion of management, are necessary to present fairly the financial information set forth herein in accordance with GAAP. The condensed consolidated balance sheet at December 31, 2020 is derived from the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. The condensed consolidated financial statements as presented reflect certain reclassifications from previously issued financial statements to conform to the current year presentation. The accounts of wholly-owned subsidiaries are included in the condensed consolidated financial statements. Intercompany accounts and transactions have been eliminated in consolidation. The results of operations for these interim periods are not necessarily indicative of results that may be expected for any other interim periods or for the full year.
Concentration of Major Customers	Concentration of Major Customers 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 Company also sells EXPAREL directly to ambulatory surgery centers and physicians. The Company sells its bupivacaine liposome injectable suspension for veterinary use to a third-party licensee and sells iovera° directly to end users.
Recent Accounting Pronouncements/ Recent Accounting Pronouncements Not Adopted	Recently Adopted Accounting Pronouncements In December 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes, which amended the approaches and methodologies in accounting for income taxes during interim periods and makes changes to certain income tax classifications. The standard allows for certain exceptions, including the exception to the use of the incremental approach for intra-period tax allocations, when there is a loss from continuing operations and income or a gain from other items, and to the general methodology for calculating income taxes in an interim period, when a year-to-date loss exceeds the anticipated loss for the year. The standard also required franchise or similar taxes partially based on income to be reported as income tax and to reflect the effects of enacted changes in tax laws or rates in the annual effective tax rate computation from the date of enactment. Lastly, in future acquisitions, the Company will be required to evaluate when the step-up in the tax basis of goodwill is part of the business combination and when it should be considered a separate transaction. The standard became effective for the Company beginning January 1, 2021 and there were no material impacts to the consolidated financial statements upon adoption. Recent Accounting Pronouncements Not Adopted as of September 30, 2021 In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40), which limits the number of convertible instruments that require separate accounting to (i) those with embedded conversion features that are not clearly and closely related to the debt, that meet the definition of a derivative, and that do not qualify for the scope exception from derivative accounting and (ii) convertible debt instruments issued with substantial premiums for which the premiums are recorded as paid-in capital. The other separation models would be eliminated, including the model for convertible debt that can be settled in cash or shares. As a result, these convertible debt instruments will be accounted for as a single liability instrument. In addition, the new guidance requires diluted earnings per share calculations to be prepared using the if-converted method, instead of the treasury stock method. The guidance must be applied in fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. The Company plans to adopt the new guidance using a modified retrospective method of transition, which would be applied to transactions outstanding at the time of adoption. At September 30, 2021, the Company has recognized debt discounts of $68.7 million for its 0.750% convertible senior notes due 2025 and $3.8 million for its 2.375% convertible senior notes due 2022. Upon adoption on January 1, 2022, these debt discounts would be eliminated along with any related future amortization. Further deferred financing costs previously allocated to the conversion features will be re-allocated to the outstanding debt, slightly increasing future annual amortization of deferred financing costs. The Company expects the impact of this standard to be material to its consolidated financial statements and related disclosures.