Pacira BioSciences (PCRX) 10-K 20 Feb 20 2019 FY Annual report Financial data

Cover Document

Cover Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 16, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-35060
Entity Registrant Name	PACIRA BIOSCIENCES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	51-0619477
Entity Address, Address Line One	5 Sylvan Way, Suite 300
Entity Address, City or Town	Parsippany,
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07054
City Area Code	(973)
Local Phone Number	254-3560
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	PCRX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 848.3
Entity Common Stock, Shares Outstanding		42,033,039
Entity Central Index Key	0001396814
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 78,228,000	$ 132,526,000
Short-term investments	213,722,000	250,928,000
Accounts receivable, net	47,530,000	38,000,000
Inventories, net	58,296,000	48,569,000
Prepaid expenses and other current assets	10,781,000	7,946,000
Total current assets	408,557,000	477,969,000
Long-term investments	64,798,000	25,871,000
Fixed assets, net	104,681,000	108,670,000
Operating Lease, Right-of-Use Asset	38,124,000	0
Goodwill	99,547,000	62,040,000
Intangible Assets, Net (Excluding Goodwill)	104,387,000	0
Equity investment and other assets	10,971,000	14,803,000
Total assets	831,065,000	689,353,000
Current liabilities:
Accounts payable	12,799,000	14,368,000
Accrued expenses	70,427,000	45,865,000
Operating Lease, Liability, Current	4,935,000	0
Convertible senior notes	0	338,000
Contingent Consideration, Current	18,179,000	0
Income taxes payable	1,333,000	90,000
Total current liabilities	107,673,000	60,661,000
Convertible senior notes	306,045,000	290,592,000
Operating Lease, Liability, Noncurrent	40,938,000	0
Contingent Consideration, Noncurrent	19,963,000	0
Other liabilities	1,502,000	16,874,000
Total liabilities	476,121,000	368,127,000
Commitments and contingencies
Stockholders’ equity:
Preferred stock, par value $0.001; 5,000,000 shares authorized; none issued and outstanding at December 31, 2019 and 2018	0	0
Common stock, par value $0.001; 250,000,000 shares authorized; 41,908,148 shares issued and outstanding at December 31, 2019; 41,222,799 shares issued and outstanding at December 31, 2018	42,000	41,000
Additional paid-in capital	753,978,000	709,691,000
Accumulated deficit	(399,398,000)	(388,226,000)
Accumulated other comprehensive income (loss)	322,000	(280,000)
Total stockholders’ equity	354,944,000	321,226,000
Total liabilities and stockholders’ equity	$ 831,065,000	$ 689,353,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	41,908,148	41,222,799
Common stock, shares outstanding	41,908,148	41,222,799

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Collaborative licensing and milestone revenue	$ 0	$ 3,000,000	$ 387,000
Total revenues	421,026,000	337,277,000	286,630,000
Operating expenses:
Cost of goods sold	106,712,000	86,845,000	87,915,000
Research and development	72,119,000	55,688,000	57,290,000
Selling, general and administrative	200,782,000	177,265,000	161,494,000
Amortization of acquired intangible assets	5,703,000	0	0
Acquisition-related charges, product discontinuation and other	25,230,000	1,564,000	4,868,000
Total operating expenses	410,546,000	321,362,000	311,567,000
Income (loss) from operations	10,480,000	15,915,000	(24,937,000)
Other (expense) income:
Interest income	7,376,000	6,497,000	4,078,000
Interest expense	(23,628,000)	(21,949,000)	(18,047,000)
Loss on early extinguishment of debt	0		(3,732,000)
Other, net	(4,976,000)	(888,000)	167,000
Total other expense, net	(21,228,000)	(16,340,000)	(17,534,000)
Loss before income taxes	(10,748,000)	(425,000)	(42,471,000)
Income tax expense	(268,000)	(46,000)	(140,000)
Net loss	$ (11,016,000)	$ (471,000)	$ (42,611,000)
Net loss per share:
Basic and diluted net income (loss) per common share (in dollars per share)	$ (0.27)	$ (0.01)	$ (1.07)
Weighted average common shares outstanding:
Basic and diluted (in shares)	41,513	40,911	39,806
Product [Member]
Revenues:
Revenues	$ 418,926,000	$ 332,427,000	$ 284,342,000
Royalty [Member]
Revenues:
Revenues	$ 2,100,000	$ 1,850,000	$ 1,901,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (11,016)	$ (471)	$ (42,611)
Other comprehensive income (loss):
Net unrealized gain (loss) on investments	602	174	(424)
Total other comprehensive income (loss)	602	174	(424)
Comprehensive loss	$ (10,414)	$ (297)	$ (43,035)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Convertible debt	Convertible Senior Notes Due 2022 [Member]	Common Stock	Additional Paid-In Capital	Additional Paid-In CapitalConvertible debt	Additional Paid-In CapitalConvertible Senior Notes Due 2022 [Member]	Accumulated Deficit	Accumulated Other Comprehensive Income
Balances at Dec. 31, 2016	$ 218,976			$ 37	$ 565,207			$ (346,238)	$ (30)
Balances (in shares) at Dec. 31, 2016				37,481,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	6,778			$ 1	6,777
Exercise of stock options (in shares)				540,000
Vested restricted stock units	0
Vested restricted stock units (in shares)				101,000
Shares issued under employee stock purchase plan	1,862				1,862
Shares issued under employee stock purchase plan (in shares)				57,000
Stock-based compensation	31,601				31,601
Issuance of common stock upon conversion of 2019 convertible senior notes	120,960			$ 3	120,957
Issuance of common stock upon conversion of 2019 convertible senior notes (in shares)				2,490,000
Equity component of convertible senior notes, net of issuance costs		$ (126,328)	$ 68,669			$ (126,328)	$ 68,669
Net unrealized gain (loss) on investments	(424)								(424)
Net loss	(42,611)							(42,611)
Balances at Dec. 31, 2017	279,483			$ 41	669,032			(389,136)	(454)
Balances (in shares) at Dec. 31, 2017				40,669,000
Increase (Decrease) in Stockholders' Equity
Net loss	(10,680)
Balances at Dec. 31, 2017	279,483			$ 41	669,032			(389,136)	(454)
Balances (in shares) at Dec. 31, 2017				40,669,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	7,170			$ 0	7,170
Exercise of stock options (in shares)				333,000
Vested restricted stock units	0			$ 0
Vested restricted stock units (in shares)				156,000
Shares issued under employee stock purchase plan	1,784				1,784
Shares issued under employee stock purchase plan (in shares)				65,000
Stock-based compensation	31,725				31,725
Net unrealized gain (loss) on investments	174								174
Net loss	(471)							(471)
Balances at Dec. 31, 2018	321,226			$ 41	709,691			(388,226)	(280)
Balances (in shares) at Dec. 31, 2018				41,223,000
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment of the adoption of Accounting Standards Update 2016-09	1,361							1,361
Net loss	2,564
Cumulative effect adjustment of the adoption of Accounting Standards Update 2016-09					(20)			20
Net loss	(2,771)
Balances at Dec. 31, 2018	321,226			$ 41	709,691			(388,226)	(280)
Balances (in shares) at Dec. 31, 2018				41,223,000
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	8,469			$ 1	8,468
Exercise of stock options (in shares)				425,000
Vested restricted stock units	0			$ 0
Vested restricted stock units (in shares)				193,000
Shares issued under employee stock purchase plan	$ 2,402				2,402
Shares issued under employee stock purchase plan (in shares)	291,981			67,000
Stock-based compensation	$ 33,650				33,650
Equity component of convertible senior notes, net of issuance costs		$ (233)				$ (233)
Net unrealized gain (loss) on investments	602								602
Net loss	(11,016)							(11,016)
Balances at Dec. 31, 2019	354,944			$ 42	$ 753,978			(399,398)	$ 322
Balances (in shares) at Dec. 31, 2019				41,908,000
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment of the adoption of Accounting Standards Update 2016-09	$ (156)							$ (156)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 70,520	$ 48,870	$ 17,785
Operating activities:
Net loss	(11,016)	(471)	(42,611)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation of fixed assets and amortization of intangible assets	19,576	13,165	13,833
Amortization of unfavorable lease obligation and debt issuance costs	1,707	1,590	1,248
Amortization of debt discount	13,746	12,799	10,423
Loss on disposal and impairment of fixed assets	1,010	65	2,133
Loss on early extinguishment of debt	0		3,732
Stock-based compensation	33,650	31,725	31,601
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	16,672	0	0
Loss on investment (net of stock dividend) and other non-operating income, net	4,315	854	0
Changes in operating assets and liabilities (net of MyoScience, Inc. acquisition):
Accounts receivable, net	(8,524)	(5,999)	(1,721)
Inventories, net	(8,026)	(7,157)	(10,133)
Prepaid expenses and other assets	(3,885)	(3,228)	3,476
Accounts payable	(1,822)	(573)	5,712
Accrued expenses and income taxes payable	20,213	5,203	3,647
Other liabilities	(6,726)	897	(3,555)
Payment for Contingent Consideration Liability, Operating Activities	(370)	0	0
Payments to Acquire Businesses, Net of Cash Acquired	(117,691)	0	0
Payment for Contingent Consideration Liability, Financing Activities	(6,630)	0	0
Investing activities:
Purchases of fixed assets	(10,159)	(14,514)	(19,266)
Purchases of investments	(318,484)	(363,255)	(502,752)
Sales of investments	319,468	405,188	321,713
Payment of contingent consideration	0	(6,843)	(8,460)
Equity investment	(1,622)	0	(15,000)
Net cash (used in) provided by investing activities	(128,488)	20,576	(223,765)
Financing activities:
Proceeds from exercises of stock options	8,469	7,170	6,778
Proceeds from shares issued under employee stock purchase plan	2,402	1,784	1,862
Proceeds from issuance of 2022 convertible senior notes	0	0	345,000
Repayment of 2019 convertible senior notes	(338)		(118,193)
Conversion premium on 2019 convertible senior notes	(233)	0	0
Payment of debt issuance and financing costs	0	0	(11,000)
Costs for conversions of convertible senior notes	0	0	(285)
Net cash provided by financing activities	3,670	8,954	224,162
Net (decrease) increase in cash and cash equivalents	(54,298)	78,400	18,182
Cash and cash equivalents, beginning of year	132,526	54,126	35,944
Cash and cash equivalents, end of year	78,228	132,526	54,126
Supplemental cash flow information:
Cash paid for interest	8,199	8,205	6,896
Cash paid for income taxes, net of refunds	863	128	129
Non-cash investing and financing activities:
Issuance of common stock from conversion of 2019 convertible senior notes	0	0	120,960
Issuance of common stock from conversion of 2019 convertible senior notes	0	0	(126,328)
Net increase (decrease) in accrued fixed assets	125	(98)	2,189
Net increase in contingent consideration liabilities	$ 28,470	$ 0	$ 0

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts Disclosure Statement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 4,804	$ 3,300	$ 3,013	$ 3,800
Accruals	26,951	19,321	15,581
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	$ (25,447)	$ (19,034)	$ (16,368)

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	DESCRIPTION OF BUSINESS Pacira BioSciences, Inc. and its subsidiaries (collectively, the “Company” or “Pacira”) is a leading provider of non-opioid pain management and regenerative health solutions to advance and improve outcomes for health care practitioners and their patients. The Company’s long-acting, local analgesic, EXPAREL ® (bupivacaine liposome injectable suspension), was commercially launched in the United States in April 2012. EXPAREL utilizes DepoFoam ® , a unique and proprietary delivery technology that encapsulates drugs without altering their molecular structure, and releases them over a desired period of time. In April 2019, the Company added iovera° ® to its commercial offering with its acquisition of MyoScience, Inc., or MyoScience. The iovera° system is a handheld cryoanalgesia device used to deliver a precise, controlled application of cold temperature to only targeted nerves. The Company changed its name from Pacira Pharmaceuticals, Inc. to Pacira BioSciences, Inc. upon completing the acquisition of MyoScience in order to better reflect a broadening portfolio of innovative non-opioid pain management and regenerative health solutions. See Note 5, MyoScience Acquisition , for more information. Pacira is subject to risks common to companies in similar industries and stages, including, but not limited to, competition from larger companies, reliance on revenue from two products, reliance on a limited number of manufacturing sites, new technological innovations, dependence on key personnel, reliance on third-party service providers and sole source suppliers, protection of proprietary technology, compliance with government regulations and risks related to cybersecurity.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Principles of Consolidation These 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, or SEC. The accounts of wholly owned subsidiaries are included in these 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 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 equity investments, long-lived assets, goodwill, liabilities and accruals, including contingent consideration, 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. Revenue From Contracts With Customers The Company’s sources of revenue include (i) sales of EXPAREL in the United States, or U.S.; (ii) sales of iovera° in the U.S.; (iii) sales of and royalties on its bupivacaine liposome injectable suspension for veterinary use in the U.S. and (iv) license fees and milestone payments. See Note 4, Revenue , for further information on the Company’s accounting policies related to revenue from contracts with customers. Collaborative Licensing and Milestone Revenue The Company’s collaboration agreements generally involve a license to the Company’s products. In determining how and when to recognize the revenue under a collaboration agreement, the Company must assess whether the license is distinct, which depends upon whether the customer can benefit from the license and whether the license is separate from other performance obligations in the agreement. If the license is distinct, the Company must further assess whether the customer has a right to access or a right to use the license depending on whether the functionality of the license is expected to substantively change over time. If the license is not expected to substantively change, the revenue is recognized at the point in time when the license is provided. If the license is expected to substantively change, the revenue is recognized over the license period. Revenue recognition from milestone payments is dependent upon the facts and circumstances surrounding the milestone payments. Milestone payments based on a non-sales metric such as a development-based milestone (e.g. obtaining regulatory approval) represent variable consideration and are included in the transaction price subject to any constraints. If the milestone payments relate to future development, the timing of recognition depends upon historical experience and the significance a third-party has on the outcome. For milestone payments to be received upon the achievement of a sales threshold, the revenue from the milestone payments is recognized at the later of when the actual sales are incurred or the performance obligation to which the sales relate has been satisfied. Royalty Revenue Royalties are estimated and recognized as revenue when sales to the Company’s commercial partners occur, unless some constraint exists, as the royalties predominately relate to a supply agreement. Royalties are based on sales of the Company’s bupivacaine liposome injectable suspension product for veterinary use. 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. The table below includes the percentage of net product sales comprised by the Company’s three largest wholesalers in each period presented: Year Ended December 31, 2019 2018 2017 Largest wholesaler 34 % 34 % 35 % Second largest wholesaler 29 % 30 % 30 % Third largest wholesaler 26 % 26 % 26 % Total 89 % 90 % 91 % The Company had no revenue from outside the U.S. during the year ended December 31, 2019 . Revenue from outside the U.S. accounted for less than 1% of the Company’s total revenue for the year ended 2018 and 1% of the Company’s total revenue for the year ended December 31, 2017 . Research and Development Expenses Research and development expenditures are expensed as incurred. These include both internal and external costs, of which a significant portion of development activities are outsourced to third parties, including contract research organizations. Clinical trial costs are accrued over the service periods specified in contracts and adjusted as necessary based on an ongoing review of the level of effort and actual costs incurred. Research and development costs are presented net of reimbursements from commercial partners. 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, 2019 and 2018 , the Company’s net 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. Stock-Based Compensation The Company’s stock-based compensation includes grants of stock options and restricted stock units, or RSUs, 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. 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 The Company utilizes its historical volatility data to determine expected volatility over the expected option term. The Company uses an expected term based on its historical data from stock option activity. The risk-free interest rate is based on the implied yield on U.S. 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 declared or paid any dividends since inception, nor does it have any intention to do so in the foreseeable future. The Company records forfeitures as they occur rather than estimating forfeitures during each period. Cash and Cash Equivalents All highly-liquid investments with maturities of 90 days or less when purchased are considered cash equivalents. Cash equivalents include corporate debt securities, asset backed securities and money market funds. As of December 31, 2019 , the carrying value of money market funds was $28.5 million , which is included in cash and cash equivalents. As of December 31, 2018 , the carrying value of money market funds was $40.6 million , corporate debt securities was $21.4 million and asset backed securities was $4.9 million , all of which were included in cash and cash equivalents. The carrying values approximate fair value as of December 31, 2019 and 2018 . 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 maturities of greater than three months, but less than one year. Long-term investments consist of asset-backed securities collateralized by credit card receivables and corporate bonds with maturities greater than one year. 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. The Company classifies its investments as available-for-sale. 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 income (loss) and are reported as a separate component of accumulated other comprehensive income (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 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 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 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 Life 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 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, based on the present value of expected future cash flows. In subsequent periods, the Company records interest expense to accrete the ARO to its full value. Each ARO capital asset is depreciated over the depreciable term of the associated asset. Leases Effective January 1, 2019, the Company recognizes right-of-use, or ROU, assets and lease liabilities at the commencement of its lease agreements. The leases are evaluated at commencement to determine whether they should be classified as operating or financing leases. Lease costs associated with operating leases are recognized on a straight-line basis, while lease costs for financing leases are recognized over the lease term using the effective interest method. To date, the Company does not have any financing leases. The amount of ROU assets and lease liabilities to be recognized is impacted by the type of lease payments, the lease term and the incremental borrowing rate. Variable lease payments are not included at commencement and are recognized in the period in which they are incurred. The lease term is based on the contractual term and is adjusted for any renewal options or termination rights that are reasonably certain to be exercised. The incremental borrowing rate is based on the rate the Company estimates it would pay on a collateralized basis over a similar term in a similar economic environment. Acquisitions In a business combination, the acquisition method of accounting requires that the assets acquired and liabilities assumed be recorded as of the date of the acquisition at their respective fair values, with some exceptions. Assets acquired and liabilities assumed in a business combination that arise from contingencies are generally recognized at fair value. If fair value cannot be determined, the asset or liability is recognized if probable and reasonably estimable; if these criteria are not met, no asset or liability is recognized. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Any excess of the purchase price (consideration transferred) over the estimated fair values of net assets acquired is recorded as goodwill. Transaction costs and costs to restructure the acquired company are expensed as incurred. The operating results of the acquired business are reflected in the Company’s consolidated financial statements after the date of the acquisition. Contingent Consideration Subsequent to an acquisition, the Company measures contingent consideration arrangements at fair value for each period with changes in fair value recognized in the consolidated statements of operations as acquisition-related charges. Changes in contingent consideration can result from changes in the assumed achievement and timing of estimated sales, costs of goods sold and regulatory approvals. In the absence of new information, changes in fair value reflect the passage of time towards achievement of the milestones, and are accrued based on an accretion schedule. Goodwill Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in a business combination and is not amortized, but is subject to impairment at least annually or when a triggering event occurs that could indicate a potential impairment. Intangible Assets Intangible assets with definite useful lives are amortized on a straight-line basis over their estimated useful lives and are reviewed for impairment if certain events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Intangible assets are recorded at cost, net of accumulated amortization. Equity Investments The Company historically accounted for its equity investment in a minority interest of a company over which it did not exercise significant influence using the cost method. The equity investment did not have a readily determinable fair value. Effective January 1, 2018, the Company elected to account for its equity investment at its cost less impairment, if any, plus or minus any changes resulting from observable price changes in orderly transactions for a similar investment. As of the fourth quarter of 2019, the equity investment held by the Company is now publicly traded and has a readily determinable fair value. The equity investment is now measured at fair value with changes in the fair value recognized in other income (expense). Impairment of Long-Lived Assets Management reviews long-lived assets, including fixed assets and intangible 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 the 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 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 and debt discount, 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. 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 shares 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, the RSUs expected to vest, the shares to be purchased under the Company’s employee stock purchase plan (using the treasury stock method), the excess conversion value on the Company’s convertible senior notes and the shares of common stock that could be issued as consideration for contingent milestone payments. Foreign Currency Translation The balance sheet accounts of foreign subsidiaries with functional currencies other than United States Dollar are translated using the exchange rate at the respective balance sheet dates. Revenues and expenses are translated using average exchange rates for each calendar month during the year. Translation adjustments are recorded as a component of accumulated other comprehensive income (loss) in the consolidated financial statements. To date, foreign currency translation has been de minimis. Segment Reporting The Company is managed and operated as a single business focused on the discovery, development, manufacture, marketing, distribution and sale of non-opioid pain management and regenerative health solutions. The Company is managed by a single management team, and, consistent with its organizational structure, the Chief Executive Officer and Chairman manages and allocates resources at a consolidated level. Accordingly, the Company views its business as one reportable operating segment to evaluate performance, allocate resources, set operational targets and forecast its future period financial results.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	12 Months Ended
	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	Recent Accounting Pronouncements Not Adopted as of December 31, 2019 In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which required 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. The Company now includes forward-looking information to better form its credit loss estimates. This update also required 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 standard is effective for the Company beginning January 1, 2020. The Company does not believe the adoption of this standard will have a material impact on its consolidated statements of operations, stockholders’ equity or cash flows. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework. The update added the following disclosures: (i) changes in unrealized gains and losses for the period included in other comprehensive income (loss) for recurring Level 3 fair value measurements held at the end of the reporting period and (ii) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The standard will become effective for the Company beginning January 1, 2020. The Company will apply these new disclosure requirements in its consolidated financial statements beginning with the three-month period ending March 31, 2020. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update provides guidance to determine which implementation costs to capitalize as they relate to the service contract and which costs to expense. In addition, the update further defines the term of the hosting arrangement to include the non-cancelable period of the arrangement plus periods covered by (i) an option to extend the arrangement if the customer is reasonably certain to exercise that option; (ii) an option to terminate the arrangement if the customer is reasonably certain not to exercise the termination option and (iii) an option to extend (or not to terminate) the arrangement in which exercise of the option is in the control of the vendor. Any expense related to the capitalized implementation costs should be recorded in the same financial statement line item in the consolidated statements of operations as the fees associated with the hosting element of the arrangement, and the payments for capitalized implementation costs should be classified in the same manner as payments made for fees associated with the hosting element in the consolidated statements of cash flows. This standard is effective for the Company beginning January 1, 2020. The amendments could be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company has applied this standard prospectively to its implementation costs incurred beginning in 2020. Any new implementation costs incurred are classified in other assets and the amortization classified in operating expenses, separate from depreciation expense, over the term of the hosting arrangement. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes, which amends the approaches and methodologies in accounting for income taxes during interim periods and makes changes to certain income tax classifications. The new standard allows exceptions to the use of the incremental approach for intra-period tax allocation, 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 requires franchise or similar taxes partially based on income to be reported as income tax and the effects of enacted changes in tax laws or rates to be included in the annual effective tax rate computation from the date of enactment. Lastly, in any future acquisition, the Company would 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 will be effective for the Company beginning January 1, 2021, with early adoption of the amendments permitted. The Company is currently evaluating the impact from the adoption of ASU 2019-12 on its consolidated financial statements.

REVENUE

REVENUE	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE Revenue from Contracts with Customers The Company’s sources of revenue include (i) sales of EXPAREL in the U.S.; (ii) sales of iovera° in the U.S.; (iii) sales of and royalties on its bupivacaine liposome injectable suspension for veterinary use in the U.S. and (iv) license fees and milestone payments. Previously, the Company sold DepoCyt(e) to third-party licensees in the U.S. and Europe prior to its discontinuation in June 2017. The Company does not consider revenue from sources other than sales of EXPAREL to be material sources of its consolidated revenue. As such, the following disclosure only relates to revenue associated with net EXPAREL product sales. 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. Product revenue is recognized when control of the promised goods are transferred to the customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for transferring those goods. EXPAREL revenue is recorded at the time the product is delivered to the end-user. Revenues from sales of products are recorded net of returns allowances, prompt payment discounts, wholesaler service fees, volume rebates and chargebacks. These reserves are based on estimates of the amounts earned or to be claimed on the related sales. These amounts are treated as variable consideration, estimated and recognized as a reduction of the transaction price at the time of the sale, using the most likely amount method for the gross to net adjustments, except for returns, which is based on the expected value method. The Company includes these estimated amounts in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized for such transaction will not occur, or when the uncertainty associated with the variable consideration is resolved. The calculation of some of these items requires management to make estimates based on sales data, historical return data, contracts and other related information that may become known in the future. The adequacy of these provisions is reviewed on a quarterly basis. The following table provides a summary of activity with respect to the Company’s sales related allowances and accruals related to EXPAREL for the years ended December 31, 2019 , 2018 and 2017 (in thousands): Returns Allowances Prompt Payment Discounts Wholesaler Service Fees Volume Rebates and Chargebacks Total Balance at December 31, 2016 $ 1,346 $ 595 $ 735 $ 1,124 $ 3,800 Provision 716 5,806 4,403 4,656 15,581 Payments/Adjustments (1,241 ) (5,744 ) (4,299 ) (5,084 ) (16,368 ) Balance at December 31, 2017 821 657 839 696 3,013 Provision 680 6,802 5,194 6,645 19,321 Payments/Adjustments (1,157 ) (6,680 ) (4,866 ) (6,331 ) (19,034 ) Balance at December 31, 2018 344 779 1,167 1,010 3,300 Provision 783 8,426 6,267 11,475 26,951 Payments/Adjustments (587 ) (8,243 ) (5,948 ) (10,669 ) (25,447 ) Balance at December 31, 2019 $ 540 $ 962 $ 1,486 $ 1,816 $ 4,804 Accounts Receivable The majority of accounts receivable arise from product sales and represent amounts due from wholesalers, hospitals, ambulatory surgery centers and doctors. Payment terms generally range from zero to 37 days from the date of the transaction, and accordingly, there is no significant financing component. Performance Obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC 606. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. At contract inception, the Company assesses the goods promised in its contracts with customers and identifies a performance obligation for each promise to transfer to the customer a good that is distinct. When identifying individual performance obligations, the Company considers all goods promised in the contract regardless of whether explicitly stated in the customer contract or implied by customary business practices. The Company’s contracts with customers require it to transfer an individual distinct product, which represents a single performance obligation. The Company’s performance obligation with respect to its product sales is satisfied at a point in time, which transfers control upon delivery of EXPAREL to its customers. The Company considers control to have transferred upon delivery because the customer has legal title to the asset, physical possession of the asset has been transferred, the customer has significant risks and rewards of ownership of the asset and the Company has a present right to payment at that time. Disaggregated Revenue The following table represents disaggregated net product sales in the periods presented as follows (in thousands): Year Ended December 31, 2019 2018 2017 Net product sales: EXPAREL / bupivacaine liposome injectable suspension $ 411,030 $ 332,427 $ 283,252 iovera° 7,896 — — DepoCyt(e) — — 1,090 Total net product sales $ 418,926 $ 332,427 $ 284,342

MYOSCIENCE ACQUISITION (Notes)

MYOSCIENCE ACQUISITION (Notes)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	NOTE 5—MYOSCIENCE ACQUISITION On April 9, 2019, the Company acquired MyoScience (the “MyoScience Acquisition”), a privately-held medical device company, pursuant to the terms of an Agreement and Plan of Merger (the “Merger Agreement”), under which MyoScience became a wholly-owned subsidiary of the Company and was renamed Pacira CryoTech, Inc., or CryoTech. The MyoScience Acquisition added iovera° to the Company’s commercial offering. The iovera° system is a novel, United States Food and Drug Administration, or FDA, approved, non-opioid treatment that immediately alleviates pain for up to 90 days by applying intense cold to only targeted nerves in a process called cryoanalgesia. The consideration included an initial cash payment of $120.0 million , reduced by $1.0 million for post-closing purchase price adjustments and indemnification obligations incurred to date, and the initial fair value of contingent consideration in the amount of $28.5 million . The contingent consideration consists of contingent milestone payments up to an aggregate of $100.0 million upon the achievement of certain regulatory and commercial milestones, of which up to $25.0 million may be payable in shares of the Company’s common stock if achieved in 2020. Per the terms of the Merger Agreement, the Company’s obligation to make milestone payments is limited to those milestones achieved between January 1, 2019 and December 31, 2023, and are to be paid within 60 days of the end of the fiscal quarter of achievement. In the third quarter of 2019, the Company met a regulatory milestone which was previously accrued that resulted in a $7.0 million cash payment in the fourth quarter of 2019. In the fourth quarter of 2019, the Company met another regulatory milestone which was previously accrued and will result in a $5.0 million cash payment to be made in the first quarter of 2020. Additionally, in the fourth quarter of 2019, the Company recognized a third regulatory milestone in the amount of $10.0 million that will require payment in the second quarter of 2020. The Company recorded $8.9 million in acquisition-related charges in its consolidated statements of operations in 2019 related to this milestone. This milestone payment can be made in either cash or shares of the Company’s common stock (or a combination thereof), at the election of the former MyoScience shareholders. The total potential remaining milestone payments available as of December 31, 2019 are $73.0 million , which includes the milestone payments to be made in 2020. The Company has accounted for the MyoScience Acquisition using the acquisition method of accounting and, accordingly, has included the assets acquired, liabilities assumed and results of operations in the condensed consolidated financial statements from April 10, 2019 onward, the day following the acquisition date. The excess of the purchase price over the fair value of identifiable net assets acquired represents goodwill. This goodwill is primarily attributable to the value of combining iovera° and EXPAREL as a safe and effective non-opioid multimodal regimen for pain management, as well as the synergies of merging operations. The primary assets and liabilities of the business acquired include developed technology and customer relationship intangible assets, equipment, inventory, receivables, payables and accrued expenses. Inventory has been recorded at its estimated selling price less costs of distribution and a reasonable profit, and the intangible assets acquired (including developed technology and customer relationships) have been recorded at fair value as determined by the Company’s management with the assistance of a third-party valuation specialist. The Company subsequently made a tax election that allows the acquired goodwill and intangible assets to be tax deductible. See Note 16, Income Taxes , for more information. The total consideration for the MyoScience Acquisition was $147.5 million , which consisted of the following (in thousands): Amount Cash paid, adjusted for working capital items $ 119,038 Fair value of contingent consideration 28,470 Total $ 147,508 The following table sets forth the allocation of the MyoScience Acquisition purchase price to the estimated fair value of the net assets acquired at the acquisition date (in thousands): Amounts Recognized at the Acquisition Date ASSETS ACQUIRED Current assets $ 5,275 Non-current assets (other than intangible assets) 1,044 Intangible assets (excluding goodwill) 110,090 Total assets acquired (excluding goodwill) $ 116,409 LIABILITIES ASSUMED Current liabilities $ 4,436 Deferred tax liabilities, net 1,828 Other non-current liabilities 144 Total liabilities assumed 6,408 Total identifiable net assets acquired 110,001 Goodwill 37,507 Total consideration transferred $ 147,508 CryoTech results from the acquisition date of April 10, 2019 through December 31, 2019 , which are included in the condensed consolidated statements of operations, are as follows (in thousands): Classification in Condensed Consolidated Statements of Operations Acquisition Date Through December 31, 2019 Total revenues $ 7,896 Net loss $ (10,478 ) Unaudited Pro Forma Summary of Operations The following table shows the unaudited pro forma summary of operations for the year ended December 31, 2019 and 2018, as if the MyoScience Acquisition had occurred on January 1, 2018. This pro forma information does not purport to represent what the Company’s actual results would have been if the acquisition had occurred as of January 1, 2018, and is not indicative of what such results would be expected for any future period (in thousands, except per share amounts): Year Ended 2019 2018 Total revenues $ 423,475 $ 342,735 Net loss $ (16,200 ) $ (25,696 ) Pro forma basic and diluted net loss per share $ (0.39 ) $ (0.63 ) The unaudited pro forma financial information was prepared using the acquisition method of accounting and was based on the historical financial information of the Company and MyoScience. The summary pro forma financial information primarily reflects the following pro forma adjustments: • Removal of the acquisition-related transaction fees and costs, including certain stock-based compensation and other compensation expenses related to the acquisition, from the year ended December 31, 2019 ; • Removal of the income tax benefit resulting from the Company decreasing its existing valuation allowance on deferred tax assets and the income tax expense resulting from a 338(g) election recognized in the year ended December 31, 2019 ; • Removal of MyoScience’s loss on extinguishment of debt and warrant expense in the year ended December 31, 2019 ; • Removal of MyoScience’s interest expense; • Adjustments to the Company’s interest income for the cash used to acquire MyoScience; and • The addition of amortization expense on the acquired developed technology and customer relationship intangible assets.

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES The components of inventories, net are as follows (in thousands): December 31, 2019 2018 Raw materials $ 20,019 $ 19,193 Work-in-process 14,407 9,711 Finished goods 23,870 19,665 Total $ 58,296 $ 48,569 The Company is required to perform stability testing on select lots of EXPAREL. In October 2019, a single validation lot of EXPAREL manufactured at the Company’s contract manufacturing site did not meet its required stability specification. At December 31, 2019, $1.3 million was reserved due to this stability investigation. In December 2019, the Company’s contract manufacturer experienced a media fill failure, which is part of the routine aseptic manufacturing requalification program, and an investigation is underway. Based on the results of its investigation to date, the Company believes no additional inventory reserves are required related to the media fill failure. However, depending on the outcome of this investigation, it may be determined that up to $4.4 million of inventory may be unsellable. None of the EXPAREL lots that could be impacted by this media fill failure have been distributed for sale. The Company has temporarily halted production on the manufacturing line while it investigates the root cause of these failures.

FIXED ASSETS

FIXED ASSETS	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
FIXED ASSETS	FIXED ASSETS Fixed assets, net, summarized by major category, consist of the following (in thousands): December 31, 2019 2018 Machinery and equipment $ 70,078 $ 67,431 Leasehold improvements 60,441 57,955 Computer equipment and software 8,942 8,131 Office furniture and equipment 1,882 1,548 Construction in progress 38,778 35,163 Total 180,121 170,228 Less: accumulated depreciation (75,440 ) (61,558 ) Fixed assets, net $ 104,681 $ 108,670 For information on useful lives by asset category, refer to Note 2, Summary of Significant Accounting Policies . Depreciation expense for the years ended December 31, 2019 , 2018 and 2017 was $14.0 million , $13.2 million and $13.8 million , respectively. During the years ended December 31, 2019 , 2018 and 2017 , the Company capitalized interest of less than $0.1 million, $0.7 million and $1.1 million , respectively. As of December 31, 2019 and 2018 , total fixed assets, net, includes leasehold improvements and manufacturing process equipment located in Europe in the amount of $64.8 million and $64.6 million , respectively. As of December 31, 2019 and 2018 , the Company had AROs of $2.5 million and $2.2 million , respectively, included in accrued expenses and other liabilities on its consolidated balance sheet, for costs associated with returning leased space to its original condition upon the termination of certain lease agreements. The increase of $0.3 million for the year ended December 31, 2019 was due to a revision in estimated future cash flows related to the AROs (including those resulting from the MyoScience Acquisition), including $0.2 million of accretion expense. Accretion expense was $0.1 million for the year ended December 31, 2018 .

LEASES - (Notes)

LEASES - (Notes)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
LEASES	LEASES The Company leases all of its facilities, including its EXPAREL manufacturing facility in San Diego, California and its iovera° manufacturing facility in Fremont, California. These leases have remaining terms between 0.7 years and 10.7 years, some of which provide renewal options at the then-current market value. The Company also has a lease with Thermo Fisher Scientific Pharma Services, or Thermo Fisher (formerly Patheon UK Limited), for the use of their facility in Swindon, England, which is embedded in agreements the Company has with Thermo Fisher. A portion of the associated monthly base fees has been allocated to the lease component based on a relative fair value basis. The operating lease costs for the facilities include lease and non-lease components, such as common area maintenance and other common operating expenses, along with executory costs such as insurance and real estate taxes. Total operating lease costs are as follows (in thousands): Year Ended December 31, Operating Lease Costs 2019 2018 Fixed lease costs $ 6,225 $ 7,236 Variable lease costs 1,651 1,761 Total $ 7,876 $ 8,997 Supplemental cash flow information related to operating leases is as follows (in thousands): Year Ended December 31, 2019 Cash paid for operating lease liabilities, net of lease incentive $ 7,346 Right-of-use assets recorded in exchange for lease obligations $ 41,605 The Company has elected to net the amortization of the ROU asset and the reduction of the lease liability principal in accrued expenses in the condensed consolidated statement of cash flows. The Company has measured its operating lease liabilities at an estimated discount rate in which it could borrow on a collateralized basis over the remaining term for each operating lease. The weighted average remaining lease term and the weighted average discount rate are summarized as follows: December 31, 2019 Weighted average remaining lease term 9.38 years Weighted average discount rate 7.55% Maturities of the Company’s operating lease liabilities are as follows (in thousands): Year Aggregate Payments Due 2020 $ 8,223 2021 6,239 2022 5,875 2023 6,013 2024 6,155 2025 through 2030 32,830 Total lease payments 65,335 Less: imputed interest (19,462 ) Total operating lease liabilities $ 45,873 The Company has entered into one lease agreement (not included in the table above) for which there are future obligations but the lease has not yet commenced as of December 31, 2019 (in thousands): Year Aggregate Payments Due 2020 $ 2,159 2021 4,415 2022 4,548 2023 4,684 2024 4,825 2025 through 2030 29,242 Total future lease payments $ 49,873 As of December 31, 2018, aggregate annual minimum payments due under the Company’s lease obligations were as follows (in thousands): Year Aggregate Minimum Payments Due 2019 $ 8,140 2020 7,621 2021 5,295 2022 5,417 2023 5,543 2024 through 2030 14,329 Total $ 46,345

ACCRUED EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consist of the following (in thousands): December 31, 2019 2018 Accrued selling, general and administrative expenses $ 21,695 $ 14,419 Accrued research and development expenses 6,562 2,432 Other accrued operating expenses 12,955 4,281 Compensation and benefits 22,258 18,861 Accrued royalties 2,883 2,286 Accrued interest 2,048 2,053 Product returns, wholesaler service fees and other 2,026 1,533 Total $ 70,427 $ 45,865

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill In March 2007, the Company acquired from SkyePharma Holding, Inc. (now a subsidiary of Vectura Group plc), or Skyepharma, its California operating subsidiary named Pacira Pharmaceuticals, Inc. (the “Skyepharma Acquisition”). The Company’s goodwill arose in April 2012 from a contingent milestone payment to Skyepharma in connection with the Skyepharma Acquisition. The Skyepharma Acquisition was accounted for under Statement of Financial Accounting Standards 141, Accounting for Business Combinations , which was the effective GAAP standard at the Skyepharma Acquisition date. In connection with the Skyepharma Acquisition, the Company agreed to milestone payments for DepoBupivacaine products, including EXPAREL, as follows: (i) $10.0 million upon the first commercial sale in the U.S. (met April 2012); (ii) $4.0 million upon the first commercial sale in the United Kingdom, France, Germany, Italy or Spain; (iii) $8.0 million when annual net sales collected reach $100.0 million (met September 2014); (iv) $8.0 million when annual net sales collected reach $250.0 million (met June 2016); and (v) $32.0 million when annual net sales collected reach $500.0 million . For purposes of meeting future potential milestone payments, annual net sales are measured on a rolling quarterly basis. As part of the Skyepharma Acquisition, the Company agreed to pay certain earn-out payments based on a percentage of net sales of DepoBupivacaine products collected, including EXPAREL, for the term during which such sales were covered by a valid claim in certain patent rights related to EXPAREL and other biologics products. The last patents for which a valid claim existed expired on September 18, 2018 and thus, the only remaining obligations to Skyepharma are the two unmet potential milestone payments totaling $36.0 million . Any remaining milestone payments will be treated as additional costs of the Skyepharma Acquisition and, therefore, recorded as goodwill if and when each contingency is resolved. There was no change in the carrying value of goodwill related to the Skyepharma Acquisition during the year ended December 31, 2019 . The Company recorded goodwill related to contingent payments due under the Skyepharma Acquisition during the year ended December 31, 2018 , which is not deductible for income tax purposes. The change in the carrying value of the Company’s goodwill is summarized as follows (in thousands): Carrying Value Balance at December 31, 2017 $ 55,197 Percentage payments on collections of net sales of DepoBupivacaine products, including EXPAREL 6,843 Balance at December 31, 2018 62,040 Goodwill arising from the MyoScience Acquisition 37,507 Balance at December 31, 2019 $ 99,547 MyoScience Acquisition In connection with the MyoScience Acquisition, the Company recorded goodwill totaling $37.5 million . The Company subsequently made a tax election that allows the acquired goodwill and intangible assets to be tax deductible. Intangible Assets Intangible assets, net, consist of the developed technology and customer relationships that were acquired in the MyoScience Acquisition and are summarized as follows (in thousands): December 31, 2019 Gross Carrying Value Accumulated Intangible Estimated Developed technology $ 110,000 $ (5,696 ) $ 104,304 14 Years Customer relationships 90 (7 ) 83 10 Years Total intangible assets $ 110,090 $ (5,703 ) $ 104,387 There were no intangible assets, net, at December 31, 2018. Amortization expense on intangible assets for the year ended December 31, 2019 was $5.7 million . There was no amortization expense on intangible assets for the years ended December 31, 2018 and 2017 . Assuming no changes in the gross carrying amount of these intangible assets, the future amortization expense on these intangible assets will be $7.9 million annually through 2032 and $2.2 million

DEBT

DEBT	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
DEBT	DEBT Convertible Senior Notes Due 2022 On March 13, 2017, the Company completed a private placement of $345.0 million in aggregate principal amount of 2.375% convertible senior notes due 2022, or 2022 Notes, and entered into an indenture, or 2022 Indenture, with respect to the 2022 Notes. The 2022 Notes accrue interest at a fixed rate of 2.375% per year, payable semiannually in arrears on April 1 st and October 1 st of each year. The 2022 Notes mature on April 1, 2022. The total debt composition of the 2022 Notes is as follows (in thousands): December 31, 2019 2018 2.375% convertible senior notes due 2022 $ 345,000 $ 345,000 Deferred financing costs (4,143 ) (5,850 ) Discount on debt (34,812 ) (48,558 ) Total debt, net of debt discount and deferred financing costs $ 306,045 $ 290,592 Holders may convert the 2022 Notes at any time prior to the close of business on the business day immediately preceding October 1, 2021, only under the following circumstances: (i) during any calendar quarter commencing after June 30, 2017 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (ii) during the five business-day period immediately after any five consecutive trading-day period (the ‘‘measurement period’’) in which the trading price (as defined in the 2022 Indenture) per $1,000 principal amount of the 2022 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; (iii) upon the occurrence of specified corporate events, including a merger or a sale of all or substantially all of the Company’s assets; or (iv) if the Company calls the 2022 Notes for redemption, until the close of business on the business day immediately preceding the redemption date. On or after October 1, 2021, until the close of business on the second scheduled trading day immediately preceding April 1, 2022, holders may convert their 2022 Notes at any time. Upon conversion, holders will receive the principal amount of their 2022 Notes and any excess conversion value, calculated based on the per share volume-weighted average price for each of the 40 consecutive trading days during the observation period (as more fully described in the 2022 Indenture). For both the principal and excess conversion value, holders may receive cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s option. The initial conversion rate for the 2022 Notes is 14.9491 shares of common stock per $1,000 principal amount, which is equivalent to an initial conversion price of $66.89 per share of the Company’s common stock. The conversion rate will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. The initial conversion price of the 2022 Notes represents a premium of approximately 37.5% to the closing sale price of $48.65 per share of the Company’s common stock on the Nasdaq Global Select Market on March 7, 2017, the date that the Company priced the private offering of the 2022 Notes. As of December 31, 2019 , the 2022 Notes had a market price of $1,044 per $1,000 principal amount. In the event of conversion, holders would forgo all future interest payments, any unpaid accrued interest and the possibility of stock price appreciation. Upon the receipt of conversion requests, the settlement of the 2022 Notes will be paid pursuant to the terms of the 2022 Indenture. In the event that all of the 2022 Notes are converted, the Company would be required to repay the $345.0 million in principal value and any conversion premium in any combination of cash and shares of its common stock (at the Company’s option). Prior to April 1, 2020, the Company may not redeem the 2022 Notes. On or after April 1, 2020, the Company may redeem for cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s option, all or part of the 2022 Notes if the last reported sale price (as defined in the 2022 Indenture) of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading-day period ending within five trading days prior to the date on which the Company provides notice of redemption. The redemption price will equal the sum of (i) 100% of the principal amount of the 2022 Notes being redeemed, plus (ii) accrued and unpaid interest, including additional interest, if any, to, but excluding, the redemption date. In addition, calling the 2022 Notes for redemption will constitute a “make whole fundamental change” (as defined in the 2022 Indenture) and will, in certain circumstances, increase the conversion rate applicable to the conversion of such notes if it is converted in connection with the redemption. No sinking fund is provided for the 2022 Notes. If the Company undergoes a fundamental change, as defined in the 2022 Indenture, subject to certain conditions, holders of the 2022 Notes may require the Company to repurchase for cash all or part of their 2022 Notes at a repurchase price equal to 100% of the principal amount of the 2022 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if a ‘‘make-whole fundamental change’’ (as defined in the 2022 Indenture) occurs prior to April 1, 2022, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its notes in connection with the make-whole fundamental change. The 2022 Notes are the Company’s general unsecured obligations that rank senior in right of payment to all of its indebtedness that is expressly subordinated in right of payment to the 2022 Notes, and equal in right of payment to the Company’s unsecured indebtedness. The 2022 Notes are also effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness, and are structurally subordinated to any debt or other liabilities (including trade payables) of the Company’s subsidiaries. While the 2022 Notes are currently classified on the Company’s consolidated balance sheet at December 31, 2019 as long-term debt, the future convertibility and resulting balance sheet classification of this liability will be monitored at each quarterly reporting date and will be analyzed dependent upon market prices of the Company’s common stock during the prescribed measurement periods. In the event that the holders of the 2022 Notes have the right to convert the 2022 Notes at any time during the prescribed measurement period, the 2022 Notes would then be considered a current obligation and classified as such. Under ASC 470-20, Debt with Conversion and Other Options , an entity must separately account for the liability and equity components of convertible debt instruments (such as the 2022 Notes) that may be settled entirely or partially in cash upon conversion in a manner that reflects the issuer’s economic interest cost. The liability component of the instrument is valued in a manner that reflects the market interest rate for a similar nonconvertible instrument at the date of issuance. The initial carrying value of the liability component of $274.1 million was calculated using a 7.45% assumed borrowing rate. The equity component of $70.9 million , representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the 2022 Notes and was recorded in additional paid-in capital on the consolidated balance sheet at the issuance date. That equity component is treated as a discount on the liability component of the 2022 Notes, which is amortized over the five-year term of the 2022 Notes using the effective interest rate method. The equity component is not re-measured as long as it continues to meet the conditions for equity classification. The Company allocated the total transaction costs of $11.0 million related to the issuance of the 2022 Notes to the liability and equity components of the 2022 Notes based on their relative values. Transaction costs attributable to the liability component are amortized to interest expense over the five -year term of the 2022 Notes, and transaction costs attributable to the equity component are netted with the equity component in stockholders’ equity. The 2022 Notes do not contain any financial or operating covenants or any restrictions on the payment of dividends, the issuance of other indebtedness or the issuance or repurchase of securities by the Company. The 2022 Indenture contains customary events of default with respect to the 2022 Notes, including that upon certain events of default, 100% of the principal and accrued and unpaid interest on the 2022 Notes will automatically become due and payable. Convertible Senior Notes Due 2019 On February 1, 2019, the Company’s 3.25% convertible senior notes due 2019, or 2019 Notes, matured, and the Company paid the remaining $0.3 million of principal in full, plus a $0.2 million conversion premium in cash. The 2019 Notes accrued interest at a fixed rate of 3.25% per year and were payable semiannually in arrears on February 1 st and August 1 st of each year. Interest Expense The following table sets forth the total interest expense recognized in the periods presented (dollar amounts in thousands): Year Ended December 31, 2019 2018 2017 Contractual interest expense $ 8,195 $ 8,205 $ 7,344 Amortization of debt issuance costs 1,707 1,634 1,381 Amortization of debt discount 13,746 12,799 10,423 Capitalized interest and other (Note 7) (20 ) (689 ) (1,101 ) Total $ 23,628 $ 21,949 $ 18,047 Effective interest rate on convertible senior notes 7.81 % 7.81 % 7.77 %

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or be paid to transfer a liability in the principal or most advantageous market in an orderly transaction. To increase consistency and comparability in fair value measurements, the FASB established a three-level hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The three levels of fair value measurements are: • Level 1: Quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities. The fair value hierarchy gives the highest priority to Level 1 inputs. • Level 2: Observable prices that are based on inputs not quoted on active markets, but corroborated by market data. • Level 3: Unobservable inputs that are used when little or no market data is available. The fair value hierarchy gives the lowest priority to Level 3 inputs. The carrying value of financial instruments including cash and cash equivalents, accounts receivable and accounts payable approximate their respective fair values due to the short-term nature of these items. The fair value of the Company’s equity investment is calculated utilizing market quotations from a major American stock exchange (Level 1). The fair value of the Company’s convertible senior notes are calculated utilizing market quotations from an over-the-counter trading market for these notes (Level 2). The fair value of the Company’s acquisition-related contingent consideration is reported at fair value on a recurring basis (Level 3). The carrying values and fair values of the Company’s financial assets and liabilities at December 31, 2019 are as follows (in thousands): Carrying Fair Value Measurements Using Level 1 Level 2 Level 3 Financial Assets: Equity investment $ 10,024 $ 10,024 $ — $ — Financial Liabilities: 2.375% convertible senior notes due 2022 (1) (2) $ 306,045 $ — $ 360,094 $ — Acquisition-related contingent consideration (3) $ 38,142 $ — $ — $ 38,142 (1) The closing price of the Company’s common stock was $45.30 per share at December 31, 2019 compared to a conversion price of $66.89 per share. Therefore, at December 31, 2019 , the conversion price was above the stock price. The maximum conversion premium that can be due on the 2022 Notes is approximately 5.2 million shares of the Company’s common stock, which assumes no increases in the conversion rate for certain corporate events. (2) Reported at historical cost. (3) Reported at fair value on a recurring basis. Financial Liabilities Measured at Fair Value on a Recurring Basis The Company has recognized contingent consideration related to the MyoScience Acquisition in the amount of $38.1 million as of December 31, 2019 . Refer to Note 5, MyoScience Acquisition , for more information. The Company’s contingent consideration obligations are recorded at their estimated fair values and are revalued each reporting period if and until the related contingencies are resolved. For the year ended December 31, 2019 , the Company recognized $16.7 million of fair value adjustments related to contingent consideration, which have been included in acquisition-related charges in the consolidated statements of operations. The Company has measured the fair value of its contingent consideration using a probability-weighted discounted cash flow approach that is based on unobservable inputs and a Monte Carlo simulation. These inputs include, as applicable, estimated probabilities and the timing of achieving specified commercial and regulatory milestones, estimated forecasts of revenue and costs and the discount rate used to calculate the present value of estimated future payments. Significant changes may increase or decrease the probabilities of achieving the related commercial and regulatory events, shorten or lengthen the time required to achieve such events, or increase or decrease estimated forecasts. The following table includes the key assumptions used in the valuation of the Company’s contingent consideration: Assumption Ranges Utilized as of December 31, 2019 Discount rates 7.57% to 7.75% Probabilities of payment for regulatory milestones 3% to 100% Projected years of payment for regulatory and commercial milestones 2020 to 2023 The maximum remaining potential payments related to the contingent consideration from the MyoScience Acquisition are $73.0 million , including a $5.0 million and a $10.0 million payment to be made in the first and second quarter of 2020, respectively. The change in the Company’s contingent consideration recorded at fair value using Level 3 measurements is as follows (in thousands): Contingent Balance at December 31, 2018 $ — New financial liabilities entered into on date of MyoScience Acquisition (April 9, 2019) 28,470 Fair value adjustments and accretion 16,672 Payments made (7,000 ) Balance at December 31, 2019 $ 38,142 Investments Short-term investments consist of asset-backed securities collateralized by credit card receivables, investment grade commercial paper and corporate bonds with maturities greater than three months, but less than one year. Long-term investments consist of asset-backed securities collateralized by credit card receivables and corporate bonds with maturities greater than one year. Net unrealized gains and losses from the Company’s short-term and long-term investments are reported in other comprehensive income (loss). At December 31, 2019 , all of the Company’s short-term and long-term investments are classified as available for sale investments and are determined to be Level 2 instruments, which are measured at fair value using standard industry models with observable inputs. The fair value of the commercial paper is measured based on a standard industry model that uses the three-month U.S. Treasury bill rate as an observable input. The fair value of the asset-backed securities and corporate bonds is principally measured or corroborated by trade data for identical issues in which related trading activity is not sufficiently frequent to be considered a Level 1 input or that of comparable securities. At December 31, 2019 , all short-term and long-term investments had an “A” or better rating by Standard & Poor’s. The following summarizes the Company’s investments at December 31, 2019 and 2018 (in thousands): December 31, 2019 Investments: Cost Gross Gross Fair Value Short-term: Asset-backed securities $ 43,166 $ 54 $ — $ 43,220 Commercial paper 32,250 20 — 32,270 Corporate bonds 138,012 225 (5 ) 138,232 Subtotal 213,428 299 (5 ) 213,722 Long-term: Asset-backed securities 28,064 10 (15 ) 28,059 Corporate bonds 36,706 37 (4 ) 36,739 Subtotal 64,770 47 (19 ) 64,798 Total $ 278,198 $ 346 $ (24 ) $ 278,520 December 31, 2018 Investments: Cost Gross Gross Fair Value Short-term: Asset-backed securities $ 34,873 $ — $ (33 ) $ 34,840 Commercial paper 45,035 — (30 ) 45,005 Corporate bonds 171,289 — (206 ) 171,083 Subtotal 251,197 — (269 ) 250,928 Long-term: Asset-backed securities 9,383 5 — 9,388 Corporate bonds 16,499 — (16 ) 16,483 Subtotal 25,882 5 (16 ) 25,871 Total $ 277,079 $ 5 $ (285 ) $ 276,799 Certain assets and liabilities are measured at fair value on a nonrecurring basis, including assets and liabilities acquired in a business combination, and long-lived assets, which would be recognized at fair value if deemed to be impaired or if reclassified as assets held for sale. The fair value in these instances would be determined using Level 3 inputs. Equity Investment At December 31, 2019 and 2018, the Company held an equity investment in TELA Bio, Inc., or TELA Bio, in its consolidated balance sheets in the amount of $10.0 million and $14.1 million , respectively. During the year ended December 31, 2019, the Company made an additional cash investment of $1.6 million in TELA Bio and received a non-cash stock dividend from TELA Bio in the amount of $2.5 million . During the years ended December 31, 2019 and 2018, the Company recorded impairment losses in the amount of $5.7 million and $0.9 million , respectively, in other, net in its consolidated statements of operations. The fair value at December 31, 2019 was based on a Level 1 input and the fair value at December 31, 2018 was based on a Level 3 input. Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, short-term investments, long-term investments and accounts receivable. The Company maintains its cash and cash equivalents with high-credit quality financial institutions. Such amounts may exceed federally-insured limits. As of December 31, 2019 , three wholesalers accounted for over 10% of the Company’s accounts receivable: 37% , 29% and 26% , respectively. At December 31, 2018 , three wholesalers accounted for over 10% of the Company’s accounts receivable: 32% , 32% and 29% , respectively. For additional information regarding the Company’s wholesalers, see Note 2 , Summary of Significant Accounting Policies . EXPAREL revenues are primarily derived from major wholesalers and pharmaceutical companies which generally have significant cash resources. The Company performs ongoing credit evaluations of its customers as warranted and generally does not require collateral. Allowances for doubtful accounts receivable are maintained based on historical payment patterns, aging of accounts receivable and actual write-off history. As of December 31, 2019 and 2018 , no allowances for doubtful accounts were deemed necessary by the Company on its accounts receivable.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY Common Stock The Company is authorized to issue up to 250,000,000 shares of common stock, of which 41,908,148 and 41,222,799 were issued and outstanding at December 31, 2019 and 2018 , respectively. Preferred Stock The Company is authorized to issue up to 5,000,000 shares of preferred stock. No preferred stock was issued or outstanding at either December 31, 2019 or 2018 . Accumulated Other Comprehensive Income (Loss) The following table illustrates the changes in the balances of the Company’s accumulated other comprehensive income (loss) for the periods presented (in thousands): Net Unrealized Gains (Losses) From Available For Sale Investments Balance at December 31, 2017 $ (454 ) Other comprehensive income before reclassifications 174 Amounts reclassified from accumulated other comprehensive income (loss) — Balance at December 31, 2018 (280 ) Other comprehensive income before reclassifications 602 Amounts reclassified from accumulated other comprehensive income (loss) — Balance at December 31, 2019 $ 322

STOCK PLANS

STOCK PLANS	12 Months Ended
	Dec. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK PLANS	STOCK PLANS Stock Incentive Plans The Company’s amended and restated 2011 stock incentive plan, or 2011 Plan, was originally adopted by its board of directors and approved by its stockholders in June 2014 and amended in both June 2016 and June 2019. The June 2019 amendment and approval by the Company’s stockholders increased the number of shares of common stock authorized for issuance as equity awards under the plan by 3,000,000 shares. The 2011 Plan allows the granting of incentive stock options, non-statutory stock options, restricted stock awards and other stock-based awards. Since the adoption of the 2011 Plan, any remaining shares available for issuance under a 2007 stock incentive plan, or 2007 Plan, are automatically reallocated to the 2011 Plan. In April 2014, the Company’s board of directors also adopted the 2014 Inducement Plan. All of the Company’s stock option grants have an exercise price equal to the closing price of the Company’s common stock on the date of grant, generally have a 10-year contractual term and vest in increments (generally over four years from the date of grant although the Company may occasionally grant options with different vesting terms). The Company also grants RSUs to employees and non-employee directors. The Company uses authorized and unissued shares to satisfy its obligations under these plans. 2014 Employee Stock Purchase Plan The Company’s 2014 Employee Stock Purchase Plan, or ESPP, was adopted by its board of directors in April 2014 and approved by the Company’s stockholders in June 2014. The purpose of the ESPP is to provide a vehicle for eligible employees to purchase shares of the Company’s common stock at a discounted price and to help retain and motivate current employees as well as attract new talent. Under the ESPP, up to 500,000 shares of common stock may be sold. The plan expires in June 2024. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Internal Revenue Code, or IRC. The maximum fair market value of stock which can be purchased by a participant in a calendar year is $ 25,000 . Six-month offering periods begin on January 1 and July 1 of each year. During an offering period, eligible employees have the opportunity to elect to purchase shares of the Company’s common stock on the purchase dates of June 30 and December 31 (or the last trading day of an offering period). The per share purchase price will be equal to the lesser of 85% of the fair market value of the Company’s common stock on either the offering date or the purchase date. During the year ended December 31, 2019 , 67,094 shares were purchased and issued through the ESPP. The following tables contain information about the Company’s stock incentive plans at December 31, 2019 : Stock Incentive Plan Awards Reserved For Issuance Awards Awards Available For Grant 2007 Plan 2,022,837 2,022,837 — 2011 Plan 12,931,700 10,047,564 2,884,136 2014 Inducement Plan 175,000 36,576 138,424 15,129,537 12,106,977 3,022,560 Employee Stock Purchase Plan Shares Reserved Shares Shares Available 2014 ESPP 500,000 291,981 208,019 Stock-Based Compensation Compensation expense for stock options and RSUs is based on the estimated grant date fair value of options recognized over the requisite service period on a straight-line expense attribution method. Compensation expense for ESPP share options is based on the estimated grant date fair value of the ESPP shares and the grant date number of shares that can be purchased, which is recognized as expense over the length of an offering period. The Company recognized stock-based compensation expense in its consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 as follows (in thousands): Year Ended December 31, 2019 2018 2017 Cost of goods sold $ 4,665 $ 4,478 $ 5,467 Research and development 5,114 3,934 3,341 Selling, general and administrative 23,871 23,313 22,793 Total $ 33,650 $ 31,725 $ 31,601 Stock-based compensation from: Stock options $ 23,360 $ 22,643 $ 24,223 RSUs 9,511 8,371 6,698 ESPP 779 711 680 Total $ 33,650 $ 31,725 $ 31,601 The following table summarizes the Company’s stock option activity and related information for the period from December 31, 2016 to December 31, 2019 : Number of Weighted Weighted Average Aggregate Outstanding at December 31, 2016 5,207,743 $ 42.16 7.39 $ 37,581 Granted 1,072,625 43.93 Exercised (539,989 ) 12.55 $ 15,865 Forfeited (555,897 ) 48.66 Expired (232,989 ) 74.65 Outstanding at December 31, 2017 4,951,493 43.51 6.91 $ 57,021 Granted 1,994,332 39.35 Exercised (332,732 ) 21.55 $ 7,418 Forfeited (481,126 ) 42.30 Expired (409,149 ) 68.01 Outstanding at December 31, 2018 5,722,818 41.69 7.07 $ 49,166 Granted 1,872,758 42.75 Exercised (425,495 ) 19.90 $ 9,441 Forfeited (286,779 ) 39.22 Expired (176,924 ) 63.33 Outstanding at December 31, 2019 6,706,378 $ 42.80 7.05 $ 50,652 Exercisable at December 31, 2019 3,536,615 $ 44.02 5.45 $ 37,569 Vested and expected to vest at December 31, 2019 6,706,378 $ 42.80 7.05 $ 50,652 As of December 31, 2019 , $57.5 million of total unrecognized compensation cost related to non-vested stock options is expected to be recognized over a weighted average period of 2.8 years . The Company’s stock options have a maximum expiration date of ten years from the date of grant. The weighted average fair value of stock options granted for the years ended December 31, 2019 , 2018 and 2017 was $20.92 , $19.34 and $20.78 per share, respectively. The fair values of stock options granted were estimated using the Black-Scholes model with the following weighted average assumptions: Year Ended December 31, Black-Scholes Weighted Average Assumption 2019 2018 2017 Expected dividend yield None None None Risk-free interest rate 1.33% - 2.54% 2.26% - 3.05% 1.68% - 2.42% Expected volatility 53.9% 53.3% 51.4% Expected term of options 5.22 years 5.14 years 5.31 years The following table summarizes the Company’s RSU activity and related information for the period from December 31, 2016 to December 31, 2019 : Number Weighted Aggregate Unvested at December 31, 2016 364,403 $ 52.85 $ 11,824 Granted 343,583 44.23 Vested (101,379 ) 53.76 Forfeited (107,061 ) 49.98 Unvested at December 31, 2017 499,546 47.32 $ 22,804 Granted 331,129 38.36 Vested (156,450 ) 49.59 Forfeited (96,261 ) 43.92 Unvested at December 31, 2018 577,964 42.14 $ 24,864 Granted 305,418 43.56 Vested (192,760 ) 45.55 Forfeited (59,481 ) 41.22 Unvested and expected to vest at December 31, 2019 631,141 $ 41.87 $ 28,591 As of December 31, 2019 , $20.5 million of total unrecognized compensation cost related to non-vested RSUs is expected to be recognized over a weighted average period of 2.7 years . The Company’s RSUs have a maximum vest date of four years from the date of grant. The fair values of RSUs awarded are equal to the closing price of the Company’s common stock on the date of grant. The fair values of the ESPP share options granted were estimated using the Black-Scholes model with the following weighted average assumptions: Year Ended December 31, Black-Scholes Weighted Average Assumption 2019 2018 2017 ESPP share option fair value $11.13 - $11.36 $10.40 - $13.15 $10.80 - $13.85 Expected dividend yield None None None Risk-free interest rate 2.10% - 2.56% 1.53% - 2.14% 0.62% - 1.14% Expected volatility 40.2% 52.2% 53.8% Expected term of ESPP share options 6 months 6 months 6 months

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NET INCOME (LOSS) PER SHARE Potential common shares are excluded from the diluted net income (loss) per share computation to the extent that they would be antidilutive. Because the Company reported a net loss for the years ended December 31, 2019 , 2018 and 2017 , no potentially dilutive securities have been included in the computation of diluted net loss per share for those periods. As discussed in Note 11, Debt , the Company has the option to pay cash for the aggregate principal amount due upon the conversion of its 2022 Notes. Since it is the Company’s intent to settle the principal amount of its 2022 Notes in cash, the potentially dilutive effect of such notes on net income (loss) per share is computed under the treasury stock method. In 2018 and 2019, because it was the Company’s intent to settle the conversion premium of its 2019 Notes in cash (as it did upon maturity on February 1, 2019), there was no potentially dilutive effect on the computation of diluted securities. The following table sets forth the computation of basic and diluted net income (loss) per share for the years ended December 31, 2019 , 2018 and 2017 (in thousands, except per share amounts): Year Ended December 31, 2019 2018 2017 Numerator: Net loss $ (11,016 ) $ (471 ) $ (42,611 ) Denominator: Weighted average shares of common stock outstanding—basic and diluted 41,513 40,911 39,806 Net loss per share: Basic and diluted net loss per common share $ (0.27 ) $ (0.01 ) $ (1.07 ) The following outstanding stock options, RSUs, conversion premiums on the Company’s convertible senior notes and ESPP purchase options are antidilutive in the periods presented (in thousands): Year Ended December 31, 2019 2018 2017 Weighted average number of stock options 6,404 5,492 5,171 Weighted average number of RSUs 606 542 449 Conversion premium on the 2019 Notes — — 411 Weighted average ESPP purchase options 34 31 29 Total 7,044 6,065 6,060

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income (loss) before income taxes and the related tax expense (benefit) is as follows (in thousands): Year Ended December 31, 2019 2018 2017 Income (loss) before income taxes: Domestic $ (71 ) $ 5,169 $ (39,898 ) Foreign (10,677 ) (5,594 ) (2,573 ) Total loss before income taxes $ (10,748 ) $ (425 ) $ (42,471 ) Current taxes: Federal $ — $ (96 ) $ — State 2,096 142 140 Total current taxes $ 2,096 $ 46 $ 140 Deferred taxes: Federal $ (1,828 ) $ — $ — Total deferred taxes $ (1,828 ) $ — $ — Total income tax expense $ 268 $ 46 $ 140 Tax expense for the year ended December 31, 2019 consists primarily of state income taxes in jurisdictions where the availability of carryforward losses are either limited or fully utilized as well as state taxes on the one-time gain from the deemed sale of assets resulting from an IRC section 338(g) tax election made by the Company related to the MyoScience Acquisition. This was partially offset by a reduction in the Company’s valuation allowance on its deferred tax assets due to the MyoScience Acquisition. The tax expense for each of the years ended December 31, 2018 and 2017 are principally the result of minimum state taxes. A reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes is as follows: Year Ended December 31, 2019 2018 2017 U.S. federal statutory rate 21.00 % 21.00 % 35.00 % State taxes (7.33 )% (24.84 )% 2.26 % Foreign taxes (3.95 )% (92.04 )% (1.28 )% Change in valuation allowance 19.76 % 369.27 % 4.58 % Stock-based compensation (10.53 )% (874.29 )% (1.21 )% Tax credits 19.93 % 700.35 % 4.96 % Interest expense — % 218.47 % 2.90 % Effect of rate changes (0.42 )% 13.44 % (130.88 )% Convertible senior notes refinancing — % — % 6.55 % Effect of the adoption of ASU 2016-09 — % — % 68.89 % Nondeductible expenses (13.58 )% (132.96 )% — % Reserves (15.41 )% (202.98 )% (2.47 )% 338(g) tax election (9.61 )% — % — % Other (2.35 )% (6.15 )% 10.37 % Effective tax rate (2.49 )% (10.73 )% (0.33 )% The Company’s effective tax rates of (2.49)% , (10.73)% and (0.33)% for the years ended December 31, 2019 , 2018 and 2017, respectively, differed from the expected U.S. statutory tax rate of 21.0% for 2019 and 2018 and from 35.0% for 2017. This difference was primarily driven by pretax losses for which the Company concluded that a majority of its tax benefits are not more-likely-than-not to be realized, resulting in the recording of a full valuation allowance. Deferred taxes reflect the tax effects of the differences between the amounts recorded as assets and liabilities for financial reporting purposes and the comparable amounts recorded for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities at December 31, 2019 and 2018 are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 66,638 $ 79,446 Federal and state credits 16,895 17,730 Depreciation and amortization 16,541 2,851 Accruals and reserves 8,756 11,009 Stock based compensation 21,663 18,302 Inventory 1,542 848 Other 2,022 127 Total deferred tax assets 134,057 130,313 Deferred tax liabilities: Discount on convertible senior notes (8,383 ) (11,655 ) Deferred tax assets, net of deferred tax liabilities 125,674 118,658 Less: valuation allowance (125,674 ) (118,658 ) Net deferred tax assets $ — $ — As of December 31, 2019 , the Company’s federal net operating losses, or NOLs, and federal tax credit carryforwards totaled $288.6 million and $11.8 million , respectively. The Company also had state NOLs and state tax credit carryforwards of $161.9 million and $6.4 million , respectively, which are subject to change on an annual basis due to variations in the Company’s annual state apportionment factors. The Company had non-U.S. tax NOLs of $13.6 million at December 31, 2019 . The existing federal NOLs will begin expiring in 2026 while the existing state NOLs begin expiring in 2024, if the Company has not used them prior to that time. The non-U.S. NOLs do not expire. Since the Company had cumulative changes in ownership of more than 50% within a three-year period, under IRC sections 382 and 383, the Company’s ability to use certain net operating loss and credit carryforwards to offset taxable income or tax will be limited. Such ownership changes were triggered by the initial acquisition of the Company’s stock in 2007 as well as cumulative ownership changes arising as a result of the completion of the Company’s initial public offering and other financing transactions. As a result of these ownership changes, the Company estimates that approximately $181.0 million of federal net operating losses are subject to annual limitations. At December 31, 2019 , $108.0 million of these federal net operating losses were available. The Company estimates that an additional $10.3 million will come available each year from 2020 through 2022, $3.5 million in 2023, $1.4 million in each of 2024 and 2025 and that the remaining $35.8 million will expire unused. In addition, California and certain states have previously suspended or limited the use of NOL carryforwards for certain taxable years, and certain states are considering similar future measures. As a result, the Company may incur higher state income tax expense in the future. In accordance with ASC Topic 740, the Company establishes a valuation allowance for deferred tax assets that, in its judgment, are not more-likely-than-not realizable. These judgments are based on projections of future income, including tax-planning strategies, by individual tax jurisdictions. In each reporting period, the Company assesses the likelihood that its deferred tax assets will be realized and determines if adjustments to its valuation allowance is appropriate. The Company had a net increase in its valuation allowance of $7.0 million for the year ended December 31, 2019 and a net reduction of $1.6 million for the year ended December 31, 2018 . The current year net increase in the Company’s valuation allowance includes a reduction of $1.8 million as a result of the MyoScience Acquisition. There is significant doubt regarding the Company’s ability to utilize its net deferred tax assets and, therefore, the Company has recorded a full valuation allowance reducing its net deferred tax assets to zero at both December 31, 2019 and 2018 . In December 2017, new legislation was signed into law reducing the corporate U.S. tax rate from 35% to 21% for tax years beginning after December 31, 2017, fully repealing the corporate alternative minimum tax and making the NOL carryforward period indefinite for NOLs generated after 2017. In accordance with ASC Topic 740, deferred tax assets and liabilities are required to be measured at the enacted tax rate expected to apply when temporary differences are to be realized or settled. As of December 31, 2017, the Company re-measured its deferred tax balances based upon the new 21% tax rate. This resulted in a reduction of $55.7 million in the Company’s deferred tax assets, which was offset by a change in its year-end valuation allowance. In March 2017, the Company established a deferred tax liability with an offset to additional paid-in capital resulting from the conversion feature of the 2022 Notes. The initial difference between the book value of the convertible debt, issued with a beneficial conversion feature, and its tax basis was $70.9 million , a temporary difference. The net effect of the deferred tax liability recorded to additional paid-in capital was zero because the Company has a full valuation allowance against its net deferred tax assets. In 2019, the Company recorded a reserve of $1.7 million related to unrecognized tax benefits, or UTBs, which relates to tax positions taken during the year. The Company’s UTB liability at December 31, 2019 was $4.5 million . The change in the Company’s UTBs in 2019 is summarized as follows (in thousands): Unrecognized Tax Benefit Balance at December 31, 2018 $ 2,881 Additions for current year positions 1,656 Balance at December 31, 2019 $ 4,537 The Company regularly assesses the likelihood of additional tax assessments by jurisdiction and, if necessary, adjusts its reserve for UTBs based on new information or developments. Due to the Company’s tax credit carryforwards, the reserve was recorded as a reduction of the Company’s deferred tax assets, and any potential deficiency would not result in a tax liability. Therefore, no interest or penalties were recognized in income tax expense for the years ended December 31, 2019 , 2018 and 2017 . Due to the Company’s full valuation allowance against deferred tax assets, none of the UTBs, if recognized, would affect the effective income tax rate. The Company estimates that it is not reasonably possible that within the next twelve months, any of the unrecognized tax benefits will significantly increase or decrease. The Company is currently subject to audit by the U.S. Internal Revenue Service, or IRS, for the years 2016 through 2019, and state tax jurisdictions for the years 2015 through 2019. However, the IRS or states may still examine and adjust an NOL arising from a closed year to the extent it is utilized in a year that remains subject to audit. The Company’s previously filed income tax returns are not presently under audit by the IRS or state tax authorities.

OTHER EMPLOYEE BENEFITS

OTHER EMPLOYEE BENEFITS	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
OTHER EMPLOYEE BENEFITS	OTHER EMPLOYEE BENEFITS The Company’s 401(k) plan is a deferred salary arrangement under section 401(k) of the IRC. Under the 401(k) plan, participating U.S. employees may defer a portion of their pre-tax earnings which are eligible for a discretionary percentage match as defined in the 401(k) plan and determined by the Company’s board of directors. The Company recognized $2.6 million , $1.6 million and $1.3 million of related compensation expense for the years ended December 31, 2019 , 2018 and 2017 , respectively.

ACQUISITION-RELATED CHARGES AND

ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET	ACQUISITION–RELATED CHARGES AND PRODUCT DISCONTINUATION, NET MyoScience Acquisition The Company recognized acquisition-related charges of $21.6 million during the year ended December 31, 2019 related to the MyoScience Acquisition. The acquisition-related charges reflect increases in the fair value of contingent consideration in the amount of $16.7 million during the year ended December 31, 2019. See Note 12, Financial Instruments , for information regarding the method and key assumptions used in the fair value measurements of contingent consideration. In addition, $4.2 million of acquisition-related charges, representing advisory costs, including legal, financial, accounting and tax services, were incurred during the year ended December 31, 2019. The remaining $0.7 million incurred during year ended December 31, 2019 represented separation costs, asset write-downs and other restructuring charges. The Company did not incur any acquisition-related charges in 2018 or 2017. See Note 5, MyoScience Acquisition , for more information. In conjunction with the MyoScience Acquisition, the Company initiated a restructuring through a headcount reduction in the sales and administrative functions. In addition, the Company terminated a number of existing distributor agreements that were maintained by MyoScience. These eliminations resulted in the write-off of demonstration equipment held by former employees and distributors. DepoCyt(e) Discontinuation The Company recorded charges of $0.2 million , $1.6 million and $5.4 million , in the years ended December 31, 2019, 2018 and 2017, respectively, related to the discontinuation of its DepoCyt(e) manufacturing activities. Production at the Company’s DepoCyt(e) manufacturing facility ceased in June 2017. Cash payments related to the lease of the idle DepoCyt(e) manufacturing facility are expected to cease once the lease term expires in August 2020. In April 2018, the Company received formal notice of the termination of a Supply Agreement and a Distribution Agreement (and all related agreements as subsequently amended) from Mundipharma International Corporation Limited and Mundipharma Medical Company, respectively (collectively, “Mundipharma”). In November 2019, the Company reached a settlement with Mundipharma and made a $5.3 million payment related to the DepoCyt(e) discontinuation which had previously been accrued. Summary of Acquisition-Related Restructuring Activities and DepoCyt(e) Discontinuation Costs At January 1, 2019, there was a balance sheet reclassification from the lease cost reserves related to the DepoCyt(e) discontinuation to lease liabilities in the amount of $1.5 million , recognized as part of the transition to the ASU 2016-02. See Note 2, Summary of Significant Accounting Policies , for more information. The Company’s acquisition-related restructuring and DepoCyt(e) discontinuation costs as of December 31, 2019 are summarized below (in thousands): Severance and Related Costs Lease Costs Write-off of Property, Plant & Equipment and Inventory AROs, Other Restructuring and Discontinuation Costs Total Balance at December 31, 2016 $ — $ — $ — $ — $ — Charges incurred 303 2,018 2,470 656 5,447 Cash payments made (303 ) (744 ) — (420 ) (1,467 ) Disposal of property, plant & — — (2,470 ) — (2,470 ) Balance sheet reclassifications — 494 — 73 567 Balance at December 31, 2017 — 1,768 — 309 2,077 Charges incurred — 1,513 — 51 1,564 Cash payments made — (1,311 ) — (91 ) (1,402 ) Balance sheet reclassifications — — — 13 13 Balance at December 31, 2018 — 1,970 — 282 2,252 Charges incurred 429 — 193 225 847 Cash payments made (348 ) — — (404 ) (752 ) Other, including non-cash activity — — (193 ) — (193 ) Balance sheet reclassifications — (1,970 ) — 455 (1,515 ) Balance at December 31, 2019 $ 81 $ — $ — $ 558 $ 639 Thermo Fisher Scientific Pharma Services (Formerly Patheon UK Limited) In April 2014, the Company and Thermo Fisher entered into a Strategic Co-Production Agreement, a Technical Transfer and Service Agreement and a Manufacturing and Supply Agreement to collaborate in the manufacture of EXPAREL. Under the terms of the Technical Transfer and Service Agreement, Thermo Fisher agreed to undertake certain technical transfer activities and construction services needed to prepare its Swindon, England facility for the manufacture of EXPAREL in two dedicated manufacturing suites. The Company contracted to purchase EXPAREL from Thermo Fisher, beginning with FDA approval of the suites, which occurred in May 2018. Commercial production began in February 2019. Under these agreements, the Company makes monthly base fee payments to Thermo Fisher. Unless earlier terminated by giving notice of up to three years (other than termination by the Company in the event of a material breach by Thermo Fisher), this agreement will expire in May 2028. DePuy Synthes Sales, Inc. In January 2017, the Company announced the initiation of a Co-Promotion Agreement, or the Agreement, with DePuy Synthes Sales, Inc., or DePuy Synthes, part of the Johnson & Johnson family of companies, to market and promote the use of EXPAREL for orthopedic procedures in the U.S. DePuy Synthes field representatives, specializing in joint reconstruction, spine, sports medicine, trauma and cranio-maxillofacial (CMF) procedures, collaborate with and supplement the Company’s field teams by expanding the reach and frequency of EXPAREL education in the hospital surgical suite and ambulatory surgery center settings. Under the five-year arrangement, DePuy Synthes is the exclusive third-party distributor during the term of the Agreement to promote and sell EXPAREL for operating room use for orthopedic and spine surgeries (including knee, hip, shoulder, sports and trauma surgeries) in the U.S. DePuy Synthes receives a tiered commission ranging from low single-digits to double-digits on sales of EXPAREL under the Agreement, subject to conditions, limitations and adjustments. The initial term of the Agreement commenced on January 24, 2017 and ends on December 31, 2021, with the option to extend the Agreement in additional 12-month increments upon mutual agreement of the parties, subject to certain conditions. The Company and DePuy Synthes have mutual termination rights under the Agreement, subject to certain terms, conditions and advance notice requirements, provided that the Company or DePuy Synthes generally may not terminate the Agreement, without cause, within three years of the effective date of the Agreement. The Company also has additional unilateral termination rights under certain circumstances. The Agreement contains customary representations, warranties, covenants and confidentiality provisions, as well as mutual indemnification obligations. DePuy Synthes is also subject to certain obligations and restrictions, including required compliance with certain laws and regulations and the Company’s policies, in connection with fulfilling their obligations under the Agreement. Aratana Therapeutics, Inc. On December 5, 2012, the Company entered into a worldwide license, development and commercialization agreement with Aratana Therapeutics, Inc., a wholly owned subsidiary of Elanco Animal Health, Inc., or Aratana. Under the agreement, the Company granted Aratana an exclusive royalty-bearing license, including the limited right to grant sublicenses, for the development and commercialization of the Company’s bupivacaine liposome injectable suspension product for veterinary use. Under the agreement, Aratana developed and obtained FDA approval for the use of the product in veterinary surgery to manage postsurgical pain. In connection with its entry into the license agreement, the Company received a one-time payment of $1.0 million . In December 2013, the Company received a $0.5 million milestone payment under the agreement. In June 2016, the Company recorded $1.0 million in milestone revenue for Aratana’s filing of an FDA Administrative New Animal Drug Application, or ANADA, and in August 2016 recorded $1.0 million related to the FDA’s approval of the ANADA. The Company is eligible to receive up to an additional aggregate $40.0 million upon the achievement of commercial milestones. Aratana is required to pay the Company a tiered double-digit royalty on certain net sales made in the U.S. If the product is approved by foreign regulatory agencies for sale outside of the U.S., Aratana will be required to pay the Company a tiered double-digit royalty on such net sales. Royalty rates will be reduced by a certain percentage upon the entry of a generic competitor for animal health indications into a jurisdiction or if Aratana must pay royalties to third parties under certain circumstances. Unless terminated earlier pursuant to its terms, the license agreement is effective until July 2033, after which Aratana has the option to extend the agreement for an additional five-year term, subject to certain requirements. Aratana began purchasing bupivacaine liposome injectable suspension product in 2016, which they market under the trade name NOCITA ® (a registered trademark of Aratana) for veterinary use. Nuance Biotech Co. Ltd. In June 2018, the Company entered into an agreement with Nuance Biotech Co. Ltd., or Nuance, a China-based specialty pharmaceutical company, to advance the development and commercialization of EXPAREL in China. Under the terms of the agreement, the Company agreed to be the sole supplier of EXPAREL to Nuance and has granted Nuance the exclusive rights to develop and commercialize EXPAREL in China. In June 2018, the Company recognized an upfront payment of $3.0 million since collaborative licensing revenue is recognized at the point in time when the license is provided and is not expected to substantively change. This payment was received in July 2018 and the Company is eligible to receive future milestone payments of up to $60.0 million that are triggered by filing for and securing regulatory approval(s) and annual sales in China exceeding certain levels. The Company is also entitled to tiered royalties as a percentage of net sales.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS In April 2012, the Company entered into a consulting agreement with Dr. Gary Pace, a director of the Company. The Company recorded no expense under the consulting agreement in the years ended December 31, 2019 , 2018, or 2017. In connection with the consulting agreement, Dr. Pace received an option to purchase 20,000 shares of common stock at an exercise price of $11.02 per share and an option to purchase 70,000 shares of common stock at an exercise price of $16.67 per share. At December 31, 2019 and 2018 , there was nothing payable to Dr. Pace for consulting services.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Litigation From time to time, the Company has been and may again become involved in legal proceedings arising in the ordinary course of its business, including those related to patents, product liability and government investigations. Except as described below, the Company is not presently a party to any legal proceedings which it believes to be material, and is not aware of any pending or threatened litigation against the Company which it believes could have a material adverse effect on its business, operating results, financial condition or cash flows. In April 2015, the Company received a subpoena from the U.S. Department of Justice, U.S. Attorney’s Office for the District of New Jersey, requiring the production of a broad range of documents pertaining to marketing and promotional practices related to EXPAREL. The Company is cooperating with the government’s inquiry. The Company can make no assurances as to the time or resources that will need to be devoted to this inquiry or the impact, if any, of this inquiry or any proceedings on its business, financial condition, results of operations and cash flows. In December 2019, the Company reached an agreement in principle with the Department of Justice and more than one state Attorney General’s office (the “Plaintiffs”) on a proposal for a global civil settlement in the amount of $3.5 million , subject to accrual of interest on the settlement amount from the date of the agreement in principle, negotiation of a definitive settlement agreement and other contingencies. As part of the settlement, the Company will admit no wrongdoing and will explicitly deny the Plaintiffs’ allegations. The Company has been given assurances that, if the parties can agree to negotiation of the settlement, this will conclude the investigation that originated from the U.S. Department of Justice subpoena in April 2015. This settlement was recorded in acquisition-related charges, product discontinuation and other in the consolidated financial statements for the year ended December 31, 2019 . Purchase Obligations The Company has approximately $25.5 million of minimum, non-cancelable contractual commitments for contract manufacturing services and $0.3 million of minimum, non-cancelable contractual commitments for the purchase of certain raw materials as of December 31, 2019 . Other Commitments and Contingencies The FDA, as a condition of EXPAREL approval, has required the Company to study EXPAREL in pediatric patients. The Company was granted a deferral for the required pediatric trials in all age groups for EXPAREL in the setting of wound infiltration and is conducting these pediatric trials as post-marketing requirements, as stated in the New Drug Application (NDA) approval letter for EXPAREL. In December 2019, the Company announced positive results for its extended pharmacokinetic and safety study for local analgesia in children aged 6 to 17 undergoing cardiovascular or spine surgeries. Those positive results will provide the foundation for a supplemental New Drug Application (sNDA). In addition to the initial $19.6 million purchase price for the Skyepharma Acquisition, the Company entered into an earn-out agreement with Skyepharma based on the Company reaching certain revenue milestones following the Skyepharma Acquisition. Pursuant to this agreement, the Company is required to pay Skyepharma milestone payments up to an aggregate of $62.0 million , of which $36.0 million are for potential milestones not yet met. The Company also agreed to pay certain earn-out payments based on a percentage of net sales of DepoBupivacaine products collected, including EXPAREL, for the term during which such sales were covered by a valid claim in certain patent rights related to EXPAREL and other biologics products. The last patents during which a valid claim existed expired on September 18, 2018. Refer to Note 9, Goodwill and Intangible Assets , for further discussion. Pursuant to an agreement with the Research Development Foundation, or RDF, the Company is required to pay RDF a low single-digit royalty on the collection of revenues from its DepoFoam-based products, for as long as certain patents assigned to the Company under the agreement remain valid. RDF has the right to terminate the agreement for an uncured material breach by the Company, in connection with its bankruptcy or insolvency or if it directly or indirectly opposes or disputes the validity of the assigned patent rights. Refer to Note 5, MyoScience Acquisition , for information on potential contingent milestone payments related to the MyoScience Acquisition.

SELECTED QUARTERLY FINANCIAL DA

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) The following tables present selected quarterly financial data for the years ended December 31, 2019 and 2018 . For periods where the Company reported a net loss, no potentially dilutive securities were included in the computation of diluted net loss per share. (In thousands, except per share amounts): Three Months Ended March 31, June 30, September 30, December 31, Total revenues $ 91,313 $ 102,604 $ 104,685 $ 122,424 Cost of goods sold 27,303 25,201 22,304 31,904 Total operating expenses 90,234 97,329 102,272 120,711 Net income (loss) (2,771 ) 2,730 (6,087 ) (4,888 ) Basic net income (loss) per common share (1) $ (0.07 ) $ 0.07 $ (0.15 ) $ (0.12 ) Diluted net income (loss) per common share (1) $ (0.07 ) $ 0.06 $ (0.15 ) $ (0.12 ) Three Months Ended March 31, June 30, September 30, December 31, Total revenues $ 74,607 $ 84,107 $ 83,448 $ 95,115 Cost of goods sold 22,885 20,916 19,065 23,979 Total operating expenses 81,544 77,566 79,400 82,852 Net income (loss) (10,680 ) 2,564 (640 ) 8,285 Basic and diluted net income (loss) per common share (1) $ (0.26 ) $ 0.06 $ (0.02 ) $ 0.20 (1) Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of the quarterly basic and diluted earnings per share amounts may not equal the full-year basic and diluted earnings per share computation.

COMMERCIAL PARTNERS AND OTHER A

COMMERCIAL PARTNERS AND OTHER AGREEMENTS	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Commercial Partners and Agreements	ACQUISITION–RELATED CHARGES AND PRODUCT DISCONTINUATION, NET MyoScience Acquisition The Company recognized acquisition-related charges of $21.6 million during the year ended December 31, 2019 related to the MyoScience Acquisition. The acquisition-related charges reflect increases in the fair value of contingent consideration in the amount of $16.7 million during the year ended December 31, 2019. See Note 12, Financial Instruments , for information regarding the method and key assumptions used in the fair value measurements of contingent consideration. In addition, $4.2 million of acquisition-related charges, representing advisory costs, including legal, financial, accounting and tax services, were incurred during the year ended December 31, 2019. The remaining $0.7 million incurred during year ended December 31, 2019 represented separation costs, asset write-downs and other restructuring charges. The Company did not incur any acquisition-related charges in 2018 or 2017. See Note 5, MyoScience Acquisition , for more information. In conjunction with the MyoScience Acquisition, the Company initiated a restructuring through a headcount reduction in the sales and administrative functions. In addition, the Company terminated a number of existing distributor agreements that were maintained by MyoScience. These eliminations resulted in the write-off of demonstration equipment held by former employees and distributors. DepoCyt(e) Discontinuation The Company recorded charges of $0.2 million , $1.6 million and $5.4 million , in the years ended December 31, 2019, 2018 and 2017, respectively, related to the discontinuation of its DepoCyt(e) manufacturing activities. Production at the Company’s DepoCyt(e) manufacturing facility ceased in June 2017. Cash payments related to the lease of the idle DepoCyt(e) manufacturing facility are expected to cease once the lease term expires in August 2020. In April 2018, the Company received formal notice of the termination of a Supply Agreement and a Distribution Agreement (and all related agreements as subsequently amended) from Mundipharma International Corporation Limited and Mundipharma Medical Company, respectively (collectively, “Mundipharma”). In November 2019, the Company reached a settlement with Mundipharma and made a $5.3 million payment related to the DepoCyt(e) discontinuation which had previously been accrued. Summary of Acquisition-Related Restructuring Activities and DepoCyt(e) Discontinuation Costs At January 1, 2019, there was a balance sheet reclassification from the lease cost reserves related to the DepoCyt(e) discontinuation to lease liabilities in the amount of $1.5 million , recognized as part of the transition to the ASU 2016-02. See Note 2, Summary of Significant Accounting Policies , for more information. The Company’s acquisition-related restructuring and DepoCyt(e) discontinuation costs as of December 31, 2019 are summarized below (in thousands): Severance and Related Costs Lease Costs Write-off of Property, Plant & Equipment and Inventory AROs, Other Restructuring and Discontinuation Costs Total Balance at December 31, 2016 $ — $ — $ — $ — $ — Charges incurred 303 2,018 2,470 656 5,447 Cash payments made (303 ) (744 ) — (420 ) (1,467 ) Disposal of property, plant & — — (2,470 ) — (2,470 ) Balance sheet reclassifications — 494 — 73 567 Balance at December 31, 2017 — 1,768 — 309 2,077 Charges incurred — 1,513 — 51 1,564 Cash payments made — (1,311 ) — (91 ) (1,402 ) Balance sheet reclassifications — — — 13 13 Balance at December 31, 2018 — 1,970 — 282 2,252 Charges incurred 429 — 193 225 847 Cash payments made (348 ) — — (404 ) (752 ) Other, including non-cash activity — — (193 ) — (193 ) Balance sheet reclassifications — (1,970 ) — 455 (1,515 ) Balance at December 31, 2019 $ 81 $ — $ — $ 558 $ 639 Thermo Fisher Scientific Pharma Services (Formerly Patheon UK Limited) In April 2014, the Company and Thermo Fisher entered into a Strategic Co-Production Agreement, a Technical Transfer and Service Agreement and a Manufacturing and Supply Agreement to collaborate in the manufacture of EXPAREL. Under the terms of the Technical Transfer and Service Agreement, Thermo Fisher agreed to undertake certain technical transfer activities and construction services needed to prepare its Swindon, England facility for the manufacture of EXPAREL in two dedicated manufacturing suites. The Company contracted to purchase EXPAREL from Thermo Fisher, beginning with FDA approval of the suites, which occurred in May 2018. Commercial production began in February 2019. Under these agreements, the Company makes monthly base fee payments to Thermo Fisher. Unless earlier terminated by giving notice of up to three years (other than termination by the Company in the event of a material breach by Thermo Fisher), this agreement will expire in May 2028. DePuy Synthes Sales, Inc. In January 2017, the Company announced the initiation of a Co-Promotion Agreement, or the Agreement, with DePuy Synthes Sales, Inc., or DePuy Synthes, part of the Johnson & Johnson family of companies, to market and promote the use of EXPAREL for orthopedic procedures in the U.S. DePuy Synthes field representatives, specializing in joint reconstruction, spine, sports medicine, trauma and cranio-maxillofacial (CMF) procedures, collaborate with and supplement the Company’s field teams by expanding the reach and frequency of EXPAREL education in the hospital surgical suite and ambulatory surgery center settings. Under the five-year arrangement, DePuy Synthes is the exclusive third-party distributor during the term of the Agreement to promote and sell EXPAREL for operating room use for orthopedic and spine surgeries (including knee, hip, shoulder, sports and trauma surgeries) in the U.S. DePuy Synthes receives a tiered commission ranging from low single-digits to double-digits on sales of EXPAREL under the Agreement, subject to conditions, limitations and adjustments. The initial term of the Agreement commenced on January 24, 2017 and ends on December 31, 2021, with the option to extend the Agreement in additional 12-month increments upon mutual agreement of the parties, subject to certain conditions. The Company and DePuy Synthes have mutual termination rights under the Agreement, subject to certain terms, conditions and advance notice requirements, provided that the Company or DePuy Synthes generally may not terminate the Agreement, without cause, within three years of the effective date of the Agreement. The Company also has additional unilateral termination rights under certain circumstances. The Agreement contains customary representations, warranties, covenants and confidentiality provisions, as well as mutual indemnification obligations. DePuy Synthes is also subject to certain obligations and restrictions, including required compliance with certain laws and regulations and the Company’s policies, in connection with fulfilling their obligations under the Agreement. Aratana Therapeutics, Inc. On December 5, 2012, the Company entered into a worldwide license, development and commercialization agreement with Aratana Therapeutics, Inc., a wholly owned subsidiary of Elanco Animal Health, Inc., or Aratana. Under the agreement, the Company granted Aratana an exclusive royalty-bearing license, including the limited right to grant sublicenses, for the development and commercialization of the Company’s bupivacaine liposome injectable suspension product for veterinary use. Under the agreement, Aratana developed and obtained FDA approval for the use of the product in veterinary surgery to manage postsurgical pain. In connection with its entry into the license agreement, the Company received a one-time payment of $1.0 million . In December 2013, the Company received a $0.5 million milestone payment under the agreement. In June 2016, the Company recorded $1.0 million in milestone revenue for Aratana’s filing of an FDA Administrative New Animal Drug Application, or ANADA, and in August 2016 recorded $1.0 million related to the FDA’s approval of the ANADA. The Company is eligible to receive up to an additional aggregate $40.0 million upon the achievement of commercial milestones. Aratana is required to pay the Company a tiered double-digit royalty on certain net sales made in the U.S. If the product is approved by foreign regulatory agencies for sale outside of the U.S., Aratana will be required to pay the Company a tiered double-digit royalty on such net sales. Royalty rates will be reduced by a certain percentage upon the entry of a generic competitor for animal health indications into a jurisdiction or if Aratana must pay royalties to third parties under certain circumstances. Unless terminated earlier pursuant to its terms, the license agreement is effective until July 2033, after which Aratana has the option to extend the agreement for an additional five-year term, subject to certain requirements. Aratana began purchasing bupivacaine liposome injectable suspension product in 2016, which they market under the trade name NOCITA ® (a registered trademark of Aratana) for veterinary use. Nuance Biotech Co. Ltd. In June 2018, the Company entered into an agreement with Nuance Biotech Co. Ltd., or Nuance, a China-based specialty pharmaceutical company, to advance the development and commercialization of EXPAREL in China. Under the terms of the agreement, the Company agreed to be the sole supplier of EXPAREL to Nuance and has granted Nuance the exclusive rights to develop and commercialize EXPAREL in China. In June 2018, the Company recognized an upfront payment of $3.0 million since collaborative licensing revenue is recognized at the point in time when the license is provided and is not expected to substantively change. This payment was received in July 2018 and the Company is eligible to receive future milestone payments of up to $60.0 million that are triggered by filing for and securing regulatory approval(s) and annual sales in China exceeding certain levels. The Company is also entitled to tiered royalties as a percentage of net sales.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation These 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, or SEC. The accounts of wholly owned subsidiaries are included in these 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 equity investments, long-lived assets, goodwill, liabilities and accruals, including contingent consideration, 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.
Revenue Recognition	Revenue From Contracts With Customers The Company’s sources of revenue include (i) sales of EXPAREL in the United States, or U.S.; (ii) sales of iovera° in the U.S.; (iii) sales of and royalties on its bupivacaine liposome injectable suspension for veterinary use in the U.S. and (iv) license fees and milestone payments. See Note 4, Revenue , for further information on the Company’s accounting policies related to revenue from contracts with customers. Collaborative Licensing and Milestone Revenue The Company’s collaboration agreements generally involve a license to the Company’s products. In determining how and when to recognize the revenue under a collaboration agreement, the Company must assess whether the license is distinct, which depends upon whether the customer can benefit from the license and whether the license is separate from other performance obligations in the agreement. If the license is distinct, the Company must further assess whether the customer has a right to access or a right to use the license depending on whether the functionality of the license is expected to substantively change over time. If the license is not expected to substantively change, the revenue is recognized at the point in time when the license is provided. If the license is expected to substantively change, the revenue is recognized over the license period. Revenue recognition from milestone payments is dependent upon the facts and circumstances surrounding the milestone payments. Milestone payments based on a non-sales metric such as a development-based milestone (e.g. obtaining regulatory approval) represent variable consideration and are included in the transaction price subject to any constraints. If the milestone payments relate to future development, the timing of recognition depends upon historical experience and the significance a third-party has on the outcome. For milestone payments to be received upon the achievement of a sales threshold, the revenue from the milestone payments is recognized at the later of when the actual sales are incurred or the performance obligation to which the sales relate has been satisfied. Royalty Revenue Royalties are estimated and recognized as revenue when sales to the Company’s commercial partners occur, unless some constraint exists, as the royalties predominately relate to a supply agreement. Royalties are based on sales of the Company’s bupivacaine liposome injectable suspension product for veterinary use.
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. The table below includes the percentage of net product sales comprised by the Company’s three largest wholesalers in each period presented: Year Ended December 31, 2019 2018 2017 Largest wholesaler 34 % 34 % 35 % Second largest wholesaler 29 % 30 % 30 % Third largest wholesaler 26 % 26 % 26 % Total 89 % 90 % 91 % The Company had no revenue from outside the U.S. during the year ended December 31, 2019 . Revenue from outside the U.S. accounted for less than 1% of the Company’s total revenue for the year ended 2018 and 1% of the Company’s total revenue for the year ended December 31, 2017
Research and Development Expenses	Research and Development Expenses
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, 2019 and 2018 , the Company’s net 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.
Stock-Based Compensation	Stock-Based Compensation The Company’s stock-based compensation includes grants of stock options and restricted stock units, or RSUs, 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. 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 The Company utilizes its historical volatility data to determine expected volatility over the expected option term. The Company uses an expected term based on its historical data from stock option activity. The risk-free interest rate is based on the implied yield on U.S. 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 declared or paid any dividends since inception, nor does it have any intention to do so in the foreseeable future. The Company records forfeitures as they occur rather than estimating forfeitures during each period.
Cash and Cash Equivalents	Cash and 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 maturities of greater than three months, but less than one year. Long-term investments consist of asset-backed securities collateralized by credit card receivables and corporate bonds with maturities greater than one year. 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. The Company classifies its investments as available-for-sale. 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 income (loss) and are reported as a separate component of accumulated other comprehensive income (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 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 Life 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, based on the present value of expected future cash flows. In subsequent periods, the Company records interest expense to accrete the ARO to its full value. Each ARO capital asset is depreciated over the depreciable term of the associated asset.
Lessee, Leases [Policy Text Block]	Leases Effective January 1, 2019, the Company recognizes right-of-use, or ROU, assets and lease liabilities at the commencement of its lease agreements. The leases are evaluated at commencement to determine whether they should be classified as operating or financing leases. Lease costs associated with operating leases are recognized on a straight-line basis, while lease costs for financing leases are recognized over the lease term using the effective interest method. To date, the Company does not have any financing leases. The amount of ROU assets and lease liabilities to be recognized is impacted by the type of lease payments, the lease term and the incremental borrowing rate. Variable lease payments are not included at commencement and are recognized in the period in which they are incurred. The lease term is based on the contractual term and is adjusted for any renewal options or termination rights that are reasonably certain to be exercised. The incremental borrowing rate is based on the rate the Company estimates it would pay on a collateralized basis over a similar term in a similar economic environment.
Acquisitions [Policy Text Block]	Acquisitions In a business combination, the acquisition method of accounting requires that the assets acquired and liabilities assumed be recorded as of the date of the acquisition at their respective fair values, with some exceptions. Assets acquired and liabilities assumed in a business combination that arise from contingencies are generally recognized at fair value. If fair value cannot be determined, the asset or liability is recognized if probable and reasonably estimable; if these criteria are not met, no asset or liability is recognized. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Any excess of the purchase price (consideration transferred) over the estimated fair values of net assets acquired is recorded as goodwill. Transaction costs and costs to restructure the acquired company are expensed as incurred. The operating results of the acquired business are reflected in the Company’s consolidated financial statements after the date of the acquisition.
Contingent Consideration [Policy Text Block]	Contingent Consideration Subsequent to an acquisition, the Company measures contingent consideration arrangements at fair value for each period with changes in fair value recognized in the consolidated statements of operations as acquisition-related charges. Changes in contingent consideration can result from changes in the assumed achievement and timing of estimated sales, costs of goods sold and regulatory approvals. In the absence of new information, changes in fair value reflect the passage of time towards achievement of the milestones, and are accrued based on an accretion schedule.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in a business combination and is not amortized, but is subject to impairment at least annually or when a triggering event occurs that could indicate a potential impairment.
Intangible Assets, Finite-Lived, Policy [Policy Text Block]	Intangible Assets Intangible assets with definite useful lives are amortized on a straight-line basis over their estimated useful lives and are reviewed for impairment if certain events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Intangible assets are recorded at cost, net of accumulated amortization.
Equity Investments	Equity Investments
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Management reviews long-lived assets, including fixed assets and intangible 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 the 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 and debt discount, 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.
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 shares 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, the RSUs expected to vest, the shares to be purchased under the Company’s employee stock purchase plan (using the treasury stock method), the excess conversion value on the Company’s convertible senior notes and the shares of common stock that could be issued as consideration for contingent milestone payments.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency Translation The balance sheet accounts of foreign subsidiaries with functional currencies other than United States Dollar are translated using the exchange rate at the respective balance sheet dates. Revenues and expenses are translated using average exchange rates for each calendar month during the year. Translation adjustments are recorded as a component of accumulated other comprehensive income (loss) in the consolidated financial statements. To date, foreign currency translation has been de minimis.
Segment Reporting	Segment Reporting The Company is managed and operated as a single business focused on the discovery, development, manufacture, marketing, distribution and sale of non-opioid pain management and regenerative health solutions. The Company is managed by a single management team, and, consistent with its organizational structure, the Chief Executive Officer and Chairman manages and allocates resources at a consolidated level. Accordingly, the Company views its business as one reportable operating segment to evaluate performance, allocate resources, set operational targets and forecast its future period financial results.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-02, Leases (Topic 842) , and subsequently issued clarifications and corrections to the update by issuing ASU 2018-10 in July 2018. This update required lessees to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous authoritative guidance. For income statement purposes, the new standard retained a dual model similar to Accounting Standards Codification, or ASC, 840, requiring leases to be classified as either operating or financing. Operating leases continue to result in straight-line expense while financing leases result in a front-loaded expense pattern (similar to previous accounting guidance by lessees for operating and capital leases, respectively, under ASC 840). The Company adopted ASU 2016-02 on January 1, 2019 using the effective date method. There were practical expedients available to the Company at transition that it elected to apply upon adoption. The Company did not re-assess (i) whether its contracts contained a lease under the new definition of a lease and (ii) the classification of those leases. There were no initial direct costs previously capitalized on the consolidated balance sheet. In addition, the Company applied hindsight in the determination of the lease terms, in the assessment of the likelihood that a lease renewal, termination or purchase option will be exercised, and in the assessment of any potential impairments that existed on the ROU assets recognized at adoption. The Company also elected not to recognize a ROU asset and lease liability for those leases with a remaining lease term of 12 months or less. At adoption on January 1, 2019, the lease liability was equal to the present value of future lease payments and a ROU asset was recorded based on the lease liability, adjusted for items such as prepaid and accrued lease payments. The Company recorded $36.5 million of lease liabilities and $27.6 million of ROU assets as of January 1, 2019, the difference representing previously recorded lease-related assets and liabilities. There was a cumulative-effect adjustment to accumulated deficit of $0.2 million upon adoption. The lease liability recognized upon adoption was based upon the present value of the sum of the remaining minimum lease payments (as previously identified under ASC 840), determined using the discount rate as of the date of adoption. The discount rate was based on the Company’s incremental borrowing rate on a collateralized basis over a similar remaining term and in a similar economic environment. Refer to Note 8, Leases , for further information on the Company’s existing leases. In May 2014, the FASB, issued Accounting Standards Update, or ASU, 2014-09, Revenue from Contracts with Customers. The Company adopted this standard on January 1, 2018 using the modified retrospective method and recorded a cumulative effect adjustment of $1.4 million to accumulated deficit upon adoption—the impact related to the acceleration of $1.0 million of deferred revenue and $0.4 million of royalties. Under the modified retrospective method of adoption, the comparative information in the consolidated financial statements was not revised and has been reported under ASC 605. The implementation of ASC 606 did not have a material impact on the Company’s consolidated statements of operations because the timing of revenue recognition for EXPAREL product sales did not change. Refer to Note 4, Revenue, for further information on the Company’s revenue. In January 2016, the FASB issued ASU 2016-01, Financial Instruments- Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. Under this standard, entities have the option to measure equity investments without readily determinable fair values either at fair value or at cost minus impairment, if any, plus or minus changes resulting from observable price changes for identical or similar investments of the same issuer. ASU 2016-01 became effective for the Company beginning January 1, 2018. The Company elected to measure its equity investment without a readily determinable fair value (TELA Bio, Inc.) at cost minus impairment. Refer to Note 2, Summary of Significant Accounting Policies, for further information. In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , which aligned accounting for share-based payments issued to nonemployees to that of employees under the existing guidance of Topic 718, with certain exceptions. The Company chose to early adopt ASU 2018-07 in June 2018 and recorded a cumulative effect adjustment of less than $0.1 million to accumulated deficit upon adoption. Recent Accounting Pronouncements Not Adopted as of December 31, 2019 In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which required 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. The Company now includes forward-looking information to better form its credit loss estimates. This update also required 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 standard is effective for the Company beginning January 1, 2020. The Company does not believe the adoption of this standard will have a material impact on its consolidated statements of operations, stockholders’ equity or cash flows. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework. The update added the following disclosures: (i) changes in unrealized gains and losses for the period included in other comprehensive income (loss) for recurring Level 3 fair value measurements held at the end of the reporting period and (ii) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The standard will become effective for the Company beginning January 1, 2020. The Company will apply these new disclosure requirements in its consolidated financial statements beginning with the three-month period ending March 31, 2020. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update provides guidance to determine which implementation costs to capitalize as they relate to the service contract and which costs to expense. In addition, the update further defines the term of the hosting arrangement to include the non-cancelable period of the arrangement plus periods covered by (i) an option to extend the arrangement if the customer is reasonably certain to exercise that option; (ii) an option to terminate the arrangement if the customer is reasonably certain not to exercise the termination option and (iii) an option to extend (or not to terminate) the arrangement in which exercise of the option is in the control of the vendor. Any expense related to the capitalized implementation costs should be recorded in the same financial statement line item in the consolidated statements of operations as the fees associated with the hosting element of the arrangement, and the payments for capitalized implementation costs should be classified in the same manner as payments made for fees associated with the hosting element in the consolidated statements of cash flows. This standard is effective for the Company beginning January 1, 2020. The amendments could be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company has applied this standard prospectively to its implementation costs incurred beginning in 2020. Any new implementation costs incurred are classified in other assets and the amortization classified in operating expenses, separate from depreciation expense, over the term of the hosting arrangement. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes, which amends the approaches and methodologies in accounting for income taxes during interim periods and makes changes to certain income tax classifications. The new standard allows exceptions to the use of the incremental approach for intra-period tax allocation, 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 requires franchise or similar taxes partially based on income to be reported as income tax and the effects of enacted changes in tax laws or rates to be included in the annual effective tax rate computation from the date of enactment. Lastly, in any future acquisition, the Company would 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 will be effective for the Company beginning January 1, 2021, with early adoption of the amendments permitted. The Company is currently evaluating the impact from the adoption of ASU 2019-12 on its consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of percentage of revenue comprised by the three largest customers	The table below includes the percentage of net product sales comprised by the Company’s three largest wholesalers in each period presented: Year Ended December 31, 2019 2018 2017 Largest wholesaler 34 % 34 % 35 % Second largest wholesaler 29 % 30 % 30 % Third largest wholesaler 26 % 26 % 26 % Total 89 % 90 % 91 %
Schedule of useful lives by asset category	Useful lives by asset category are as follows: Asset Category Useful Life Computer equipment and software 1 to 3 years Office furniture and equipment 5 years Manufacturing and laboratory equipment 5 to 10 years

REVENUE (Tables)

REVENUE (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Summary of Activity in Accrued Rebates and Chargebacks, Returns, Wholsesaler Service Fees and Prompt Pay Discounts	for the years ended December 31, 2019 , 2018 and 2017 (in thousands): Returns Allowances Prompt Payment Discounts Wholesaler Service Fees Volume Rebates and Chargebacks Total Balance at December 31, 2016 $ 1,346 $ 595 $ 735 $ 1,124 $ 3,800 Provision 716 5,806 4,403 4,656 15,581 Payments/Adjustments (1,241 ) (5,744 ) (4,299 ) (5,084 ) (16,368 ) Balance at December 31, 2017 821 657 839 696 3,013 Provision 680 6,802 5,194 6,645 19,321 Payments/Adjustments (1,157 ) (6,680 ) (4,866 ) (6,331 ) (19,034 ) Balance at December 31, 2018 344 779 1,167 1,010 3,300 Provision 783 8,426 6,267 11,475 26,951 Payments/Adjustments (587 ) (8,243 ) (5,948 ) (10,669 ) (25,447 ) Balance at December 31, 2019 $ 540 $ 962 $ 1,486 $ 1,816 $ 4,804
Disaggregation of Revenue	The following table represents disaggregated net product sales in the periods presented as follows (in thousands): Year Ended December 31, 2019 2018 2017 Net product sales: EXPAREL / bupivacaine liposome injectable suspension $ 411,030 $ 332,427 $ 283,252 iovera° 7,896 — — DepoCyt(e) — — 1,090 Total net product sales $ 418,926 $ 332,427 $ 284,342

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of components of inventories	The components of inventories, net are as follows (in thousands): December 31, 2019 2018 Raw materials $ 20,019 $ 19,193 Work-in-process 14,407 9,711 Finished goods 23,870 19,665 Total $ 58,296 $ 48,569

FIXED ASSETS (Tables)

FIXED ASSETS (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of fixed assets summarized by major category	Fixed assets, net, summarized by major category, consist of the following (in thousands): December 31, 2019 2018 Machinery and equipment $ 70,078 $ 67,431 Leasehold improvements 60,441 57,955 Computer equipment and software 8,942 8,131 Office furniture and equipment 1,882 1,548 Construction in progress 38,778 35,163 Total 180,121 170,228 Less: accumulated depreciation (75,440 ) (61,558 ) Fixed assets, net $ 104,681 $ 108,670

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease, Cost [Table Text Block]	Total operating lease costs are as follows (in thousands): Year Ended December 31, Operating Lease Costs 2019 2018 Fixed lease costs $ 6,225 $ 7,236 Variable lease costs 1,651 1,761 Total $ 7,876 $ 8,997 December 31, 2019 Weighted average remaining lease term 9.38 years Weighted average discount rate 7.55%
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Maturities of the Company’s operating lease liabilities are as follows (in thousands): Year Aggregate Payments Due 2020 $ 8,223 2021 6,239 2022 5,875 2023 6,013 2024 6,155 2025 through 2030 32,830 Total lease payments 65,335 Less: imputed interest (19,462 ) Total operating lease liabilities $ 45,873 The Company has entered into one lease agreement (not included in the table above) for which there are future obligations but the lease has not yet commenced as of December 31, 2019 (in thousands): Year Aggregate Payments Due 2020 $ 2,159 2021 4,415 2022 4,548 2023 4,684 2024 4,825 2025 through 2030 29,242 Total future lease payments $ 49,873
Schedule of annual minimum payments due under the Company's lease obligations	As of December 31, 2018, aggregate annual minimum payments due under the Company’s lease obligations were as follows (in thousands): Year Aggregate Minimum Payments Due 2019 $ 8,140 2020 7,621 2021 5,295 2022 5,417 2023 5,543 2024 through 2030 14,329 Total $ 46,345

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): December 31, 2019 2018 Accrued selling, general and administrative expenses $ 21,695 $ 14,419 Accrued research and development expenses 6,562 2,432 Other accrued operating expenses 12,955 4,281 Compensation and benefits 22,258 18,861 Accrued royalties 2,883 2,286 Accrued interest 2,048 2,053 Product returns, wholesaler service fees and other 2,026 1,533 Total $ 70,427 $ 45,865

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of change in carrying value of goodwill	The change in the carrying value of the Company’s goodwill is summarized as follows (in thousands): Carrying Value Balance at December 31, 2017 $ 55,197 Percentage payments on collections of net sales of DepoBupivacaine products, including EXPAREL 6,843 Balance at December 31, 2018 62,040 Goodwill arising from the MyoScience Acquisition 37,507 Balance at December 31, 2019 $ 99,547

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of composition of the Company's debt and financing obligations	The total debt composition of the 2022 Notes is as follows (in thousands): December 31, 2019 2018 2.375% convertible senior notes due 2022 $ 345,000 $ 345,000 Deferred financing costs (4,143 ) (5,850 ) Discount on debt (34,812 ) (48,558 ) Total debt, net of debt discount and deferred financing costs $ 306,045 $ 290,592
Schedule of total interest expense recognized related to the Notes	The following table sets forth the total interest expense recognized in the periods presented (dollar amounts in thousands): Year Ended December 31, 2019 2018 2017 Contractual interest expense $ 8,195 $ 8,205 $ 7,344 Amortization of debt issuance costs 1,707 1,634 1,381 Amortization of debt discount 13,746 12,799 10,423 Capitalized interest and other (Note 7) (20 ) (689 ) (1,101 ) Total $ 23,628 $ 21,949 $ 18,047 Effective interest rate on convertible senior notes 7.81 % 7.81 % 7.77 %

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of carrying amount and fair value of the long-term debt	Carrying Fair Value Measurements Using Level 1 Level 2 Level 3 Financial Assets: Equity investment $ 10,024 $ 10,024 $ — $ — Financial Liabilities: 2.375% convertible senior notes due 2022 (1) (2) $ 306,045 $ — $ 360,094 $ — Acquisition-related contingent consideration (3) $ 38,142 $ — $ — $ 38,142 (1) The closing price of the Company’s common stock was $45.30 per share at December 31, 2019 compared to a conversion price of $66.89 per share. Therefore, at December 31, 2019 , the conversion price was above the stock price. The maximum conversion premium that can be due on the 2022 Notes is approximately 5.2 million shares of the Company’s common stock, which assumes no increases in the conversion rate for certain corporate events.
Schedule of short-term investments	The following summarizes the Company’s investments at December 31, 2019 and 2018 (in thousands): December 31, 2019 Investments: Cost Gross Gross Fair Value Short-term: Asset-backed securities $ 43,166 $ 54 $ — $ 43,220 Commercial paper 32,250 20 — 32,270 Corporate bonds 138,012 225 (5 ) 138,232 Subtotal 213,428 299 (5 ) 213,722 Long-term: Asset-backed securities 28,064 10 (15 ) 28,059 Corporate bonds 36,706 37 (4 ) 36,739 Subtotal 64,770 47 (19 ) 64,798 Total $ 278,198 $ 346 $ (24 ) $ 278,520 December 31, 2018 Investments: Cost Gross Gross Fair Value Short-term: Asset-backed securities $ 34,873 $ — $ (33 ) $ 34,840 Commercial paper 45,035 — (30 ) 45,005 Corporate bonds 171,289 — (206 ) 171,083 Subtotal 251,197 — (269 ) 250,928 Long-term: Asset-backed securities 9,383 5 — 9,388 Corporate bonds 16,499 — (16 ) 16,483 Subtotal 25,882 5 (16 ) 25,871 Total $ 277,079 $ 5 $ (285 ) $ 276,799

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Schedule of accumulated other comprehensive income	The following table illustrates the changes in the balances of the Company’s accumulated other comprehensive income (loss) for the periods presented (in thousands): Net Unrealized Gains (Losses) From Available For Sale Investments Balance at December 31, 2017 $ (454 ) Other comprehensive income before reclassifications 174 Amounts reclassified from accumulated other comprehensive income (loss) — Balance at December 31, 2018 (280 ) Other comprehensive income before reclassifications 602 Amounts reclassified from accumulated other comprehensive income (loss) — Balance at December 31, 2019 $ 322

STOCK PLANS (Tables)

STOCK PLANS (Tables)	12 Months Ended
	Dec. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of information about the plans	The following tables contain information about the Company’s stock incentive plans at December 31, 2019 : Stock Incentive Plan Awards Reserved For Issuance Awards Awards Available For Grant 2007 Plan 2,022,837 2,022,837 — 2011 Plan 12,931,700 10,047,564 2,884,136 2014 Inducement Plan 175,000 36,576 138,424 15,129,537 12,106,977 3,022,560 Employee Stock Purchase Plan Shares Reserved Shares Shares Available 2014 ESPP 500,000 291,981 208,019
Schedule of recognized stock-based compensation in consolidated statements of operations	The Company recognized stock-based compensation expense in its consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 as follows (in thousands): Year Ended December 31, 2019 2018 2017 Cost of goods sold $ 4,665 $ 4,478 $ 5,467 Research and development 5,114 3,934 3,341 Selling, general and administrative 23,871 23,313 22,793 Total $ 33,650 $ 31,725 $ 31,601 Stock-based compensation from: Stock options $ 23,360 $ 22,643 $ 24,223 RSUs 9,511 8,371 6,698 ESPP 779 711 680 Total $ 33,650 $ 31,725 $ 31,601
Schedule of the Company's stock option activity and related information	The following table summarizes the Company’s stock option activity and related information for the period from December 31, 2016 to December 31, 2019 : Number of Weighted Weighted Average Aggregate Outstanding at December 31, 2016 5,207,743 $ 42.16 7.39 $ 37,581 Granted 1,072,625 43.93 Exercised (539,989 ) 12.55 $ 15,865 Forfeited (555,897 ) 48.66 Expired (232,989 ) 74.65 Outstanding at December 31, 2017 4,951,493 43.51 6.91 $ 57,021 Granted 1,994,332 39.35 Exercised (332,732 ) 21.55 $ 7,418 Forfeited (481,126 ) 42.30 Expired (409,149 ) 68.01 Outstanding at December 31, 2018 5,722,818 41.69 7.07 $ 49,166 Granted 1,872,758 42.75 Exercised (425,495 ) 19.90 $ 9,441 Forfeited (286,779 ) 39.22 Expired (176,924 ) 63.33 Outstanding at December 31, 2019 6,706,378 $ 42.80 7.05 $ 50,652 Exercisable at December 31, 2019 3,536,615 $ 44.02 5.45 $ 37,569 Vested and expected to vest at December 31, 2019 6,706,378 $ 42.80 7.05 $ 50,652
Schedule of weighted average assumptions used to estimate the fair values of each option grant using the Black-Scholes option pricing model	The fair values of stock options granted were estimated using the Black-Scholes model with the following weighted average assumptions: Year Ended December 31, Black-Scholes Weighted Average Assumption 2019 2018 2017 Expected dividend yield None None None Risk-free interest rate 1.33% - 2.54% 2.26% - 3.05% 1.68% - 2.42% Expected volatility 53.9% 53.3% 51.4% Expected term of options 5.22 years 5.14 years 5.31 years
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following table summarizes the Company’s RSU activity and related information for the period from December 31, 2016 to December 31, 2019 : Number Weighted Aggregate Unvested at December 31, 2016 364,403 $ 52.85 $ 11,824 Granted 343,583 44.23 Vested (101,379 ) 53.76 Forfeited (107,061 ) 49.98 Unvested at December 31, 2017 499,546 47.32 $ 22,804 Granted 331,129 38.36 Vested (156,450 ) 49.59 Forfeited (96,261 ) 43.92 Unvested at December 31, 2018 577,964 42.14 $ 24,864 Granted 305,418 43.56 Vested (192,760 ) 45.55 Forfeited (59,481 ) 41.22 Unvested and expected to vest at December 31, 2019 631,141 $ 41.87 $ 28,591

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted loss per share	The following table sets forth the computation of basic and diluted net income (loss) per share for the years ended December 31, 2019 , 2018 and 2017 (in thousands, except per share amounts): Year Ended December 31, 2019 2018 2017 Numerator: Net loss $ (11,016 ) $ (471 ) $ (42,611 ) Denominator: Weighted average shares of common stock outstanding—basic and diluted 41,513 40,911 39,806 Net loss per share: Basic and diluted net loss per common share $ (0.27 ) $ (0.01 ) $ (1.07 )
Schedule of potential dilutive effect of the securities excluded from the calculation of diluted loss per share	The following outstanding stock options, RSUs, conversion premiums on the Company’s convertible senior notes and ESPP purchase options are antidilutive in the periods presented (in thousands): Year Ended December 31, 2019 2018 2017 Weighted average number of stock options 6,404 5,492 5,171 Weighted average number of RSUs 606 542 449 Conversion premium on the 2019 Notes — — 411 Weighted average ESPP purchase options 34 31 29 Total 7,044 6,065 6,060

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax and Current Taxes	Income (loss) before income taxes and the related tax expense (benefit) is as follows (in thousands): Year Ended December 31, 2019 2018 2017 Income (loss) before income taxes: Domestic $ (71 ) $ 5,169 $ (39,898 ) Foreign (10,677 ) (5,594 ) (2,573 ) Total loss before income taxes $ (10,748 ) $ (425 ) $ (42,471 ) Current taxes: Federal $ — $ (96 ) $ — State 2,096 142 140 Total current taxes $ 2,096 $ 46 $ 140 Deferred taxes: Federal $ (1,828 ) $ — $ — Total deferred taxes $ (1,828 ) $ — $ — Total income tax expense $ 268 $ 46 $ 140
Schedule of reconciliation of income taxes at the U.S. Federal statutory rate to the provision for income taxes	A reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes is as follows: Year Ended December 31, 2019 2018 2017 U.S. federal statutory rate 21.00 % 21.00 % 35.00 % State taxes (7.33 )% (24.84 )% 2.26 % Foreign taxes (3.95 )% (92.04 )% (1.28 )% Change in valuation allowance 19.76 % 369.27 % 4.58 % Stock-based compensation (10.53 )% (874.29 )% (1.21 )% Tax credits 19.93 % 700.35 % 4.96 % Interest expense — % 218.47 % 2.90 % Effect of rate changes (0.42 )% 13.44 % (130.88 )% Convertible senior notes refinancing — % — % 6.55 % Effect of the adoption of ASU 2016-09 — % — % 68.89 % Nondeductible expenses (13.58 )% (132.96 )% — % Reserves (15.41 )% (202.98 )% (2.47 )% 338(g) tax election (9.61 )% — % — % Other (2.35 )% (6.15 )% 10.37 % Effective tax rate (2.49 )% (10.73 )% (0.33 )%
Schedule of significant components of the Company's deferred tax assets	Deferred taxes reflect the tax effects of the differences between the amounts recorded as assets and liabilities for financial reporting purposes and the comparable amounts recorded for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities at December 31, 2019 and 2018 are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 66,638 $ 79,446 Federal and state credits 16,895 17,730 Depreciation and amortization 16,541 2,851 Accruals and reserves 8,756 11,009 Stock based compensation 21,663 18,302 Inventory 1,542 848 Other 2,022 127 Total deferred tax assets 134,057 130,313 Deferred tax liabilities: Discount on convertible senior notes (8,383 ) (11,655 ) Deferred tax assets, net of deferred tax liabilities 125,674 118,658 Less: valuation allowance (125,674 ) (118,658 ) Net deferred tax assets $ — $ —
Schedule of Unrecognized Tax Benefits Roll Forward	The change in the Company’s UTBs in 2019 is summarized as follows (in thousands): Unrecognized Tax Benefit Balance at December 31, 2018 $ 2,881 Additions for current year positions 1,656 Balance at December 31, 2019 $ 4,537

ACQUISITION-RELATED CHARGES A_2

ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET	The Company’s acquisition-related restructuring and DepoCyt(e) discontinuation costs as of December 31, 2019 are summarized below (in thousands): Severance and Related Costs Lease Costs Write-off of Property, Plant & Equipment and Inventory AROs, Other Restructuring and Discontinuation Costs Total Balance at December 31, 2016 $ — $ — $ — $ — $ — Charges incurred 303 2,018 2,470 656 5,447 Cash payments made (303 ) (744 ) — (420 ) (1,467 ) Disposal of property, plant & — — (2,470 ) — (2,470 ) Balance sheet reclassifications — 494 — 73 567 Balance at December 31, 2017 — 1,768 — 309 2,077 Charges incurred — 1,513 — 51 1,564 Cash payments made — (1,311 ) — (91 ) (1,402 ) Balance sheet reclassifications — — — 13 13 Balance at December 31, 2018 — 1,970 — 282 2,252 Charges incurred 429 — 193 225 847 Cash payments made (348 ) — — (404 ) (752 ) Other, including non-cash activity — — (193 ) — (193 ) Balance sheet reclassifications — (1,970 ) — 455 (1,515 ) Balance at December 31, 2019 $ 81 $ — $ — $ 558 $ 639

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of annual minimum payments due under the Company's lease obligations	As of December 31, 2018, aggregate annual minimum payments due under the Company’s lease obligations were as follows (in thousands): Year Aggregate Minimum Payments Due 2019 $ 8,140 2020 7,621 2021 5,295 2022 5,417 2023 5,543 2024 through 2030 14,329 Total $ 46,345

SELECTED QUARTERLY FINANCIAL _2

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	The following tables present selected quarterly financial data for the years ended December 31, 2019 and 2018 . For periods where the Company reported a net loss, no potentially dilutive securities were included in the computation of diluted net loss per share. (In thousands, except per share amounts): Three Months Ended March 31, June 30, September 30, December 31, Total revenues $ 91,313 $ 102,604 $ 104,685 $ 122,424 Cost of goods sold 27,303 25,201 22,304 31,904 Total operating expenses 90,234 97,329 102,272 120,711 Net income (loss) (2,771 ) 2,730 (6,087 ) (4,888 ) Basic net income (loss) per common share (1) $ (0.07 ) $ 0.07 $ (0.15 ) $ (0.12 ) Diluted net income (loss) per common share (1) $ (0.07 ) $ 0.06 $ (0.15 ) $ (0.12 ) Three Months Ended March 31, June 30, September 30, December 31, Total revenues $ 74,607 $ 84,107 $ 83,448 $ 95,115 Cost of goods sold 22,885 20,916 19,065 23,979 Total operating expenses 81,544 77,566 79,400 82,852 Net income (loss) (10,680 ) 2,564 (640 ) 8,285 Basic and diluted net income (loss) per common share (1) $ (0.26 ) $ 0.06 $ (0.02 ) $ 0.20 (1) Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of the quarterly basic and diluted earnings per share amounts may not equal the full-year basic and diluted earnings per share computation.

DESCRIPTION OF BUSINESS DESCRIP

DESCRIPTION OF BUSINESS DESCRIPTION OF BUSINESS (Details)	12 Months Ended
	Dec. 31, 2019product
Sales Revenue, Net [Member] | Product Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Number Of Products	2

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) - Customer concentration - customer	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Concentration Risk, Number of Customers	3
Net revenue
Concentration Risk [Line Items]
Percentage of revenue from customers to total revenue	89.00%	90.00%	91.00%
Net revenue | Largest customer
Concentration Risk [Line Items]
Percentage of revenue from customers to total revenue	34.00%	34.00%	35.00%
Net revenue | Second largest customer
Concentration Risk [Line Items]
Percentage of revenue from customers to total revenue	29.00%	30.00%	30.00%
Net revenue | Third largest customer
Concentration Risk [Line Items]
Percentage of revenue from customers to total revenue	26.00%	26.00%	26.00%
Net revenue | Customers outside U.S.
Concentration Risk [Line Items]
Percentage of revenue from customers to total revenue	0.00%	1.00%	1.00%

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4)	12 Months Ended
	Dec. 31, 2019segment
Segment Reporting
Number of reportable segments	1
Computer equipment and software | Minimum
Fixed Assets
Useful life	1 year
Computer equipment and software | Maximum
Fixed Assets
Useful life	3 years
Office furniture and equipment
Fixed Assets
Useful life	5 years
Manufacturing and laboratory equipment | Minimum
Fixed Assets
Useful life	5 years
Manufacturing and laboratory equipment | Maximum
Fixed Assets
Useful life	10 years

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Carrying value of money market funds	$ 28.5	$ 40.6
Carrying value of commercial paper		21.4
Carrying value of asset-backed securities		$ 4.9

RECENT ACCOUNTING PRONOUNCEME_2

RECENT ACCOUNTING PRONOUNCEMENTS Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained Earnings (Accumulated Deficit)			$ (399,398)	$ (388,226)
Cumulative Effect on Retained Earnings, Net of Tax		$ 100
Operating Lease, Liability			45,873
Operating Lease, Right-of-Use Asset			$ 38,124	$ 0
Accounting Standards Update 2016-02
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ 200
Operating Lease, Liability	36,500
Operating Lease, Right-of-Use Asset	$ 27,600
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained Earnings (Accumulated Deficit)					$ 1,400
Contract with Customer, Liability					1,000
Accrued Royalties					$ 400

RECENT ACCOUNTING PRONOUNCEME_3

RECENT ACCOUNTING PRONOUNCEMENTS Stock-Based Compensation (Details) $ in Millions	Jun. 30, 2018USD ($)
Accounting Policies [Abstract]
Cumulative Effect on Retained Earnings, Net of Tax	$ 0.1

REVENUE (Details)

REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	$ 3,300	$ 3,013	$ 3,800
Accruals	26,951	19,321	15,581
Payments (Credits)	(25,447)	(19,034)	(16,368)
End of Period	4,804	3,300	3,013
Accrued returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	344	821	1,346
Accruals	783	680	716
Payments (Credits)	(587)	(1,157)	(1,241)
End of Period	540	344	821
Reserves for prompt pay discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	779	657	595
Accruals	8,426	6,802	5,806
Payments (Credits)	(8,243)	(6,680)	(5,744)
End of Period	962	779	657
Accrued wholesaler service fees
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	1,167	839	735
Accruals	6,267	5,194	4,403
Payments (Credits)	(5,948)	(4,866)	(4,299)
End of Period	1,486	1,167	839
Accrued rebates and chargebacks
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	1,010	696	1,124
Accruals	11,475	6,645	4,656
Payments (Credits)	(10,669)	(6,331)	(5,084)
End of Period	$ 1,816	$ 1,010	$ 696

REVENUE (Details 2)

REVENUE (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total net product sales	$ 418,926	$ 332,427	$ 284,342
EXPAREL/bupivacaine liposome injectable suspension [Member]
Disaggregation of Revenue [Line Items]
Total net product sales	411,030	332,427	283,252
iovera° [Member] [Member]
Disaggregation of Revenue [Line Items]
Total net product sales	7,896	0	0
DepoCyte
Disaggregation of Revenue [Line Items]
Total net product sales	$ 0	$ 0	$ 1,090
Maximum
Disaggregation of Revenue [Line Items]
Accounts Receivable, Additional Narrative Disclosure	P37D
Minimum
Disaggregation of Revenue [Line Items]
Accounts Receivable, Additional Narrative Disclosure	P0D

MYOSCIENCE ACQUISITION (Details

MYOSCIENCE ACQUISITION (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 09, 2019	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Revenues			$ 122,424	$ 104,685	$ 102,604	$ 91,313	$ 95,115	$ 83,448	$ 84,107	$ 74,607		$ 421,026	$ 337,277	$ 286,630
Acquisition-related charges, product discontinuation and other												25,230	1,564	4,868
Goodwill			99,547				$ 62,040				$ 99,547	99,547	62,040	$ 55,197
Myoscience Acquisition
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue												423,475	342,735
Revenues											7,896
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	$ 5,275
Payments to Acquire Businesses, Gross	$ 119,038
Business Combination, Contingent Consideration, Liability, Milestone Payments			73,000								73,000	73,000
Contingent Consideration, Payment Term	60 days
Business Combination, Contingent Consideration Arrangements, Maximum Amount, Payable in Shares	$ 25,000
Contingent Consideration												100,000
Business Combination, Fair Value Of Contingent Consideration	28,470
Goodwill, Translation and Purchase Accounting Adjustments												1,000
Payments for Merger Related Costs												120,000
Initial purchase price for acquisition												147,508
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Assets, Other Than Intangible Assets	1,044
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	110,090
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	116,409
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	4,436
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	1,828
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities	144
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	6,408
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	110,001
Goodwill	37,507
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 147,508
Net Income (Loss) Attributable to Noncontrolling Interest											$ (10,478)
Business Acquisition, Pro Forma Net Income (Loss)												$ (16,200)	$ (25,696)
Business Acquisition, Pro Forma Earnings Per Share, Basic And Diluted												$ (390)	$ (630)
Achievement of Regulatory Milestone [Member]
Business Acquisition [Line Items]
Payments for contingent consideration liabilities			5,000
Achievement of Regulatory Milestone [Member] | Myoscience Acquisition
Business Acquisition [Line Items]
Acquisition-related charges, product discontinuation and other			$ 8,900
Achievement of Regulatory Milestone [Domain]
Business Acquisition [Line Items]
Payments for contingent consideration liabilities				$ 7,000
Scenario, Forecast | Achievement of Regulatory Milestone [Member]
Business Acquisition [Line Items]
Payments for contingent consideration liabilities		$ 10,000

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory [Line Items]
Raw materials	$ 20,019	$ 19,193
Work-in-process	14,407	9,711
Finished goods	23,870	19,665
Total	58,296	$ 48,569
Reserved inventory	1,300
Amount of potentially unsellable inventory (up to)	$ 4,400

FIXED ASSETS (Details)

FIXED ASSETS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
FIXED ASSETS
Total	$ 180,121	$ 170,228
Less accumulated depreciation	(75,440)	(61,558)
Fixed assets, net	104,681	108,670
Depreciation expense	14,000	13,200	$ 13,800
Capitalized interest	20	689	$ 1,101
Foreign Property, Plant and Equipment, Net	64,800	64,600
Asset Retirement Obligation	2,500	2,200
Increase (Decrease) in Asset Retirement Obligations	300
Asset Retirement Obligation, Accretion Expense	200	100
Manufacturing and laboratory equipment
FIXED ASSETS
Total	70,078	67,431
Leasehold improvements
FIXED ASSETS
Total	60,441	57,955
Computer equipment and software
FIXED ASSETS
Total	8,942	8,131
Office furniture and equipment
FIXED ASSETS
Total	1,882	1,548
Construction in progress
FIXED ASSETS
Total	$ 38,778	$ 35,163

LEASES

LEASES $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due Next Twelve Months	$ 2,159
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due Thereafter	$ 29,242
Lessee, Operating Lease, Lease Not Yet Commenced, Number Of Contracts | contract	1
Operating Leases, Future Minimum Payments Due, Next Twelve Months		$ 8,140
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due Year Two	$ 4,415
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 8,223
Operating Lease, Weighted Average Remaining Lease Term	9 years 4 months 17 days
Operating Lease, Payments	$ 7,346
Operating Lease, Cost	6,225	7,236
Variable Lease, Cost	1,651	1,761
Lease, Cost	7,876	8,997
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 41,605
Operating Lease, Weighted Average Discount Rate, Percent	7.55%
Lessee, Operating Lease, Liability, Payments, Due Year Two	$ 6,239
Lessee, Operating Lease, Liability, Payments, Due Year Three	5,875
Lessee, Operating Lease, Liability, Payments, Due Year Four	6,013
Lessee, Operating Lease, Liability, Payments, Due Year Five	6,155
Lessee, Operating Lease, Liability, Payments, Due after Year Five	32,830
Lessee, Operating Lease, Liability, Payments, Due	65,335
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(19,462)
Operating Lease, Liability	45,873
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due Year Three	4,548
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due After Year Five	4,684
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Due Year Five	4,825
Operating Leases, Future Minimum Payments, Due in Two Years		7,621
Operating Leases, Future Minimum Payments, Due in Three Years		5,295
Operating Leases, Future Minimum Payments, Due in Four Years		5,417
Operating Leases, Future Minimum Payments, Due in Five Years		5,543
Operating Leases, Future Minimum Payments, Due Thereafter		14,329
Total		$ 46,345
Lessee, Operating Lease, Lease Not Yet Commenced, Liability, Payments Due	$ 49,873
Maximum
Lessee, Operating Lease, Term of Contract	10 years 8 months 12 days
Minimum
Lessee, Operating Lease, Term of Contract	8 months 12 days

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued selling, general, and administrative expenses	$ 21,695	$ 14,419
Other accrued operating expenses	22,258	18,861
Compensation and benefits	12,955	4,281
Accrued research and development expenses	6,562	2,432
Accrued royalties	2,883	2,286
Accrued interest	2,048	2,053
Product returns, wholesaler service fees and other	2,026	1,533
Total	$ 70,427	$ 45,865

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019
Goodwill
Goodwill, Acquired During Period	$ 37,507,000
Goodwill [Roll Forward]
Beginning balance	62,040,000	$ 55,197,000
Percentage payments on collections of net sales of DepoBupivacaine products, including EXPAREL		6,843,000
Ending balance	99,547,000	62,040,000	$ 55,197,000
Intangible Assets, Net (Excluding Goodwill)	104,387,000	0
Amortization of acquired intangible assets	5,703,000	$ 0	$ 0
Finite-Lived Intangible Assets, Amortization Expense, Annual Amount From 2020 To 2032	7,900,000
Finite-Lived Intangible Assets, Amortization Expense, Annual Amount In 2033				$ 2,200,000
Upon first commercial sale in the United States
Goodwill
Milestone payments for EXPAREL agreed in connection with acquisition	10,000,000
Upon first commercial sale in a major EU country (United Kingdom, France, Germany, Italy and Spain)
Goodwill
Milestone payments for EXPAREL agreed in connection with acquisition	4,000,000
When annual net sales collected reach $100.0 million
Goodwill
Milestone payments for EXPAREL agreed in connection with acquisition	8,000,000
Annual net sales threshold	100,000,000
When annual net sales collected reach $250.0 million
Goodwill
Milestone payments for EXPAREL agreed in connection with acquisition	8,000,000
Annual net sales threshold	250,000,000
When annual net sales collected reach $500.0 million
Goodwill
Milestone payments for EXPAREL agreed in connection with acquisition	32,000,000
Annual net sales threshold	500,000,000
SkyePharma Holding, Inc.
Goodwill [Roll Forward]
Total Milestone Payments Yet to be Paid for Sale of Product in Connection with Acquisition	$ 36,000,000

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS Schedule of Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	$ 104,387,000	$ 0
Amortization of acquired intangible assets	5,703,000	$ 0	$ 0
Finite-Lived Intangible Assets, Gross	110,090,000
Finite-Lived Intangible Assets, Accumulated Amortization	(5,703,000)
Finite-Lived Intangible Assets, Net	104,387,000
Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	110,000,000
Finite-Lived Intangible Assets, Accumulated Amortization	(5,696,000)
Finite-Lived Intangible Assets, Net	$ 104,304,000
Finite-Lived Intangible Asset, Useful Life	14 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 90,000
Finite-Lived Intangible Assets, Accumulated Amortization	(7,000)
Finite-Lived Intangible Assets, Net	$ 83,000
Finite-Lived Intangible Asset, Useful Life	10 years

DEBT (Details)

DEBT (Details) - USD ($)	Feb. 01, 2019	Mar. 13, 2017	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2018	Mar. 07, 2017
Debt:
Settlement Period - Convertible Debt Conversion Request		40 days
Share Price			$ 45.30
Loss on early extinguishment of debt			$ 0	$ 3,732,000
Repayments of Senior Debt	$ 300,000
Repayment of Conversion Premium	$ 200,000
Convertible Senior Notes Due 2022 [Member]
Debt:
Debt Instrument, Convertible, Conversion Ratio		14.9491
Debt Instrument, Convertible, Conversion Price		$ 66.89
Debt Instrument, Conversion Obligation Premium on Common Stock		37.50%
Share Price						$ 48.65
Debt Redemption Price Due to Fundamental Change as Percentage of Principal Amount		100.00%
Convertible Debt		$ 274,100,000
Debt Instrument, Convertible, Assumed Borrowing Rate		7.45%
Debt Instrument, Convertible, Carrying Amount of Equity Component		$ 70,900,000
Debt Related Commitment Fees and Debt Issuance Costs		$ 11,000,000
Debt Issuance Costs, Amortization period		5 years
Debt Instrument, Customary Events of Default, Percentage of Principal and Accrued and Unpaid Interest Due and Payable Upon Default		100.00%
Convertible Senior Notes Due 2022 [Member] | Debt Conversion Terms Business Day Immediately Preceding October 1, 2021 [Member]
Debt:
Debt Instrument, Conversion Obligation Common Stock Closing Sales Price Minimum, Number of Trading Days		20 days
Debt Instrument, Conversion Obligation Number of Consecutive Trading Days		30 days
Debt Instrument, Conversion Obligation Common Stock Closing Sales Price Minimum as Percentage of Conversion Price		130.00%
Debt Instrument Conversion Obligation Number of Consecutive Business Days after Consecutive Trading Day Period		5 years
Debt Instrument, Conversion Obligation Period of Consecutive Trading Days		5 years
Debt Instrument, Principal Amount Denominator for Conversion into Common Stock		$ 1,000	1,000
Debt Instrument, Conversion Obligation Trading Price as Percentage of Product of Last Reported Common Stock Sale Price and Conversion Rate Maximum		98.00%
Debt Instrument, Market Price			1,044
Convertible Senior Notes Due 2022 [Member] | Debt Redemption Terms on or after April 1, 2020 [Member]
Debt:
Debt Instrument, Conversion Obligation Common Stock Closing Sales Price Minimum, Number of Trading Days		20 days
Debt Instrument, Conversion Obligation Number of Consecutive Trading Days		30 days
Debt Instrument, Conversion Obligation Common Stock Closing Sales Price Minimum as Percentage of Conversion Price		130.00%
Debt Instrument Conversion Obligation Number of Trading Days Prior to Date on which Entity Provides Notice of Redemption		5 days
Debt Instrument, Percentage of Principal Amount for Computation of Redemption Price		100.00%
Convertible debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Debt:
Debt Instrument, Principal Amount Denominator for Conversion into Common Stock		$ 1,000
Unsecured Debt | Convertible Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 345,000,000		$ 345,000,000
Proceeds from Issuance of Debt		$ 345,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.375%	2.375%
Debt:
Debt Issuance Costs, Net			$ (4,143,000)		(5,850,000)
Discount on debt			(34,812,000)		(48,558,000)
Total debt, net of debt discount			$ 306,045,000		290,592,000
Unsecured Debt | Convertible debt
Debt:
Long-term Debt, Gross					$ 338,000

FINANCIAL INSTRUMENTS (Details)

FINANCIAL INSTRUMENTS (Details) $ / shares in Units, shares in Millions		Mar. 13, 2017$ / sharesshares	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Feb. 01, 2019	Mar. 07, 2017$ / shares
Fair Value Measurements
Price per share (in dollars per share) | $ / shares			$ 45.30
Payments to Acquire Businesses, Net of Cash Acquired			$ 117,691,000	$ 0	$ 0
Equity investment and other assets			10,971,000	14,803,000
Total Milestone Payments Yet To Be Paid in Connection with MyoScience Acquisition			73,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements			(7,000,000)
Level 2
Fair Value Measurements
Cost			278,198,000	277,079,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			346,000	5,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(24,000)	(285,000)
Available-for-sale Securities			$ 278,520,000	276,799,000
Convertible Senior Notes Due 2022 [Member]
Fair Value Measurements
Price per share (in dollars per share) | $ / shares							$ 48.65
Initial conversion price of notes into common stock (in dollars per share) | $ / shares		$ 66.89
Notes
Fair Value Measurements
Debt Instrument, Interest Rate, Stated Percentage						3.25%
Maximum | Convertible Senior Notes Due 2022 [Member]
Fair Value Measurements
Debt Instrument, Convertible, Conversion Premium, Shares | shares		5.2
Unsecured Debt | Convertible Senior Notes Due 2022 [Member]
Fair Value Measurements
Debt Instrument, Interest Rate, Stated Percentage		2.375%	2.375%
Unsecured Debt | Convertible Senior Notes Due 2022 [Member] | Level 1
Fair Value Measurements
Long-term debt-current and long-term	[1]		$ 0
Unsecured Debt | Convertible Senior Notes Due 2022 [Member] | Level 2
Fair Value Measurements
Long-term debt-current and long-term	[1]		360,094,000
Unsecured Debt | Convertible Senior Notes Due 2022 [Member] | Level 3
Fair Value Measurements
Long-term debt-current and long-term	[1]		0
Unsecured Debt | Carrying Value | Convertible Senior Notes Due 2022 [Member]
Fair Value Measurements
Long-term debt-current and long-term	[1]		306,045,000
Asset-backed securities | Level 2
Fair Value Measurements
Cost			28,064,000	9,383,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			10,000	5,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(15,000)	0
Available-for-sale Securities			28,059,000	9,388,000
Corporate bonds | Level 2
Fair Value Measurements
Cost			36,706,000	16,499,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			37,000	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(4,000)	(16,000)
Available-for-sale Securities			36,739,000	16,483,000
Corporate bonds | Level 2
Fair Value Measurements
Cost			138,012,000	171,289,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			225,000	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(5,000)	(206,000)
Available-for-sale Securities			138,232,000	171,083,000
Asset-backed securities | Level 2
Fair Value Measurements
Cost			43,166,000	34,873,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			54,000	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			0	(33,000)
Available-for-sale Securities			43,220,000	34,840,000
Long-term | Level 2
Fair Value Measurements
Cost			64,770,000	25,882,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			47,000	5,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			(19,000)	(16,000)
Available-for-sale Securities			64,798,000	25,871,000
Myoscience Acquisition
Fair Value Measurements
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease)			16,700,000
Contingent consideration liability			$ 38,100,000
Business Combination, Contingent Consideration, Liability, Milestone Achievement Period			4 years
Myoscience Acquisition | Level 1
Fair Value Measurements
Contingent consideration liability			$ 0
Myoscience Acquisition | Level 2
Fair Value Measurements
Contingent consideration liability			0
Myoscience Acquisition | Level 3
Fair Value Measurements
Contingent consideration liability			38,142,000
Myoscience Acquisition | Carrying Value
Fair Value Measurements
Contingent consideration liability			38,142,000
Investments [Member] | Carrying Value
Fair Value Measurements
Equity Method Investments, Fair Value Disclosure	[1]		10,024,000
Investments [Member] | Carrying Value | Level 1
Fair Value Measurements
Equity Method Investments, Fair Value Disclosure	[1]		10,024,000
Investments [Member] | Carrying Value | Level 2
Fair Value Measurements
Equity Method Investments, Fair Value Disclosure	[1]		0
Investments [Member] | Carrying Value | Level 3
Fair Value Measurements
Equity Method Investments, Fair Value Disclosure	[1]		0
Contingent Consideration [Member]
Fair Value Measurements
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value			38,142,000	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances			28,470,000
Fair value adjustments			16,672,000
Achievement of Regulatory Milestone [Member]
Fair Value Measurements
Contingent consideration liability			5,000,000
Achievement of Development and Commercial Milestones [Member]
Fair Value Measurements
Contingent consideration liability			$ 10,000,000
Measurement Input, Discount Rate [Member] | Myoscience Acquisition | Contingent Consideration [Member] | Minimum | Level 3
Fair Value Measurements
Business Combination, Contingent Consideration, Liability, Measurement Input			0.0757
Measurement Input, Discount Rate [Member] | Myoscience Acquisition | Contingent Consideration [Member] | Maximum | Level 3
Fair Value Measurements
Business Combination, Contingent Consideration, Liability, Measurement Input			0.0775
Measurement Input, Expected Milestone Payment [Member] | Myoscience Acquisition | Contingent Consideration [Member] | Minimum | Level 3
Fair Value Measurements
Business Combination, Contingent Consideration, Liability, Measurement Input			0.0300
Measurement Input, Expected Milestone Payment [Member] | Myoscience Acquisition | Contingent Consideration [Member] | Maximum | Level 3
Fair Value Measurements
Business Combination, Contingent Consideration, Liability, Measurement Input			1
[1]	The closing price of the Company’s common stock was $45.30 per share at December 31, 2019 compared to a conversion price of $66.89 per share. Therefore, at December 31, 2019 , the conversion price was above the stock price. The maximum conversion premium that can be due on the 2022 Notes is approximately 5.2 million shares of the Company’s common stock, which assumes no increases in the conversion rate for certain corporate events.

DEBT (Details 2)

DEBT (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest Expense, Debt [Abstract]
Amortization of debt discount	$ 13,746	$ 12,799	$ 10,423
Interest Costs Capitalized	(20)	(689)	(1,101)
Notes
Interest Expense, Debt [Abstract]
Total interest expense recognized	23,628	21,949	18,047
Convertible Debt [Member]
Interest Expense, Debt [Abstract]
Contractual interest expense	8,195	8,205	7,344
Amortization of debt issuance costs	1,707	1,634	1,381
Amortization of debt discount	$ 13,746	$ 12,799	$ 10,423
Effective interest rate (as a percent)	7.81%	7.81%	7.77%

FINANCIAL INSTRUMENTS (Details

FINANCIAL INSTRUMENTS (Details 2) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Fair Value Measurements
Equity investment and other assets		$ 10,971	$ 14,803
Realized Investment Gains (Losses)			900
Convertible Debt, Fair Value Disclosures		10,000	14,100
Payments to Acquire Long-term Investments	$ 1,600
Dividend Income, Operating		2,500
Unrealized Gain (Loss) on Investments		5,700
Level 2
Fair Value Measurements
Cost		278,198	277,079
Gross Unrealized Gains		346	5
Gross Unrealized Losses		(24)	(285)
Fair Value		278,520	276,799
Asset-backed securities | Level 2
Fair Value Measurements
Cost		43,166	34,873
Gross Unrealized Gains		54	0
Gross Unrealized Losses		0	(33)
Fair Value		43,220	34,840
Commercial paper | Level 2
Fair Value Measurements
Cost		32,250	45,035
Gross Unrealized Gains		20	0
Gross Unrealized Losses		0	(30)
Fair Value		32,270	45,005
Corporate bonds | Level 2
Fair Value Measurements
Cost		138,012	171,289
Gross Unrealized Gains		225	0
Gross Unrealized Losses		(5)	(206)
Fair Value		138,232	171,083
Short-term | Level 2
Fair Value Measurements
Cost		213,428	251,197
Gross Unrealized Gains		299	0
Gross Unrealized Losses		(5)	(269)
Fair Value		213,722	250,928
Asset-backed securities | Level 2
Fair Value Measurements
Cost		28,064	9,383
Gross Unrealized Gains		10	5
Gross Unrealized Losses		(15)	0
Fair Value		28,059	9,388
Corporate bonds | Level 2
Fair Value Measurements
Cost		36,706	16,499
Gross Unrealized Gains		37	0
Gross Unrealized Losses		(4)	(16)
Fair Value		36,739	16,483
Long-term | Level 2
Fair Value Measurements
Cost		64,770	25,882
Gross Unrealized Gains		47	5
Gross Unrealized Losses		(19)	(16)
Fair Value		$ 64,798	$ 25,871

FINANCIAL INSTRUMENTS (Detail_2

FINANCIAL INSTRUMENTS (Details 3)	12 Months Ended
	Dec. 31, 2019USD ($)customer	Dec. 31, 2018USD ($)customer
Concentration Risk [Line Items]
Allowance for Doubtful Accounts Receivable, Current | $	$ 0	$ 0
Number of major customers | customer	3	3
Accounts receivable | Credit risk | Major customer one
Concentration Risk [Line Items]
Concentration risk (as a percent)	37.00%	32.00%
Accounts receivable | Credit risk | Major customer two
Concentration Risk [Line Items]
Concentration risk (as a percent)	29.00%	32.00%
Accounts receivable | Credit risk | Major customer three
Concentration Risk [Line Items]
Concentration risk (as a percent)	26.00%	29.00%

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) - shares	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares outstanding	41,908,148	41,222,799
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0

STOCKHOLDERS' EQUITY (Details 2

STOCKHOLDERS' EQUITY (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balances at the beginning of the period	$ (280)
Balances at the end of the period	322	$ (280)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balances at the beginning of the period	(280)	(454)
Other comprehensive income before reclassifications	602	174
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Balances at the end of the period	$ 322	$ (280)

STOCK PLANS (Details)

STOCK PLANS (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award, Increase In Number of Shares Authorized	3,000,000
Awards Reserved for Issuance (in shares)		15,129,537
Employee Stock Purchase Plan (ESPP), Shares in ESPP		500,000
Maximum Fair Market Value Purchase of ESPP Shares		$ 25,000
Employee Stock Purchase Plan fair value		85.00%
Awards Issued (in shares)		12,106,977
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		3,022,560
Stock Purchased And Issued During Period, Shares, Employee Stock Purchase Plans		67,094
Employee Stock Purchase Plan, Number of Shares Authorized		500,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		291,981
Employee Stock Purchase Plan, Number of Shares Available For Purchase		208,019
Stock options
Stock Incentive Plans
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		$ 57,500,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 9 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 20.92	$ 19.34	$ 20.78
Restricted Stock Units (RSUs) [Member]
Stock Incentive Plans
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 8 months 12 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 20,500,000
Inducement Plan 2014 [Member]
Stock Incentive Plans
Awards Reserved for Issuance (in shares)		175,000
Awards Issued (in shares)		36,576
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		138,424
Two Thousand Seven Stock Incentive Plan [Member]
Stock Incentive Plans
Awards Reserved for Issuance (in shares)		2,022,837
Awards Issued (in shares)		2,022,837
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		0
Stock Incentive Plan 2011 [Member]
Stock Incentive Plans
Awards Reserved for Issuance (in shares)		12,931,700
Awards Issued (in shares)		10,047,564
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		2,884,136

STOCK PLANS (Details 2)

STOCK PLANS (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-Based Compensation
Stock-based compensation expense	$ 33,650	$ 31,725	$ 31,601
Compensation expense from stock options, employees	23,360	22,643	24,223
Restricted Stock or Unit Expense	9,511	8,371	6,698
Compensation expense from employee stock purchase plan	779	711	680
Stock-based compensation	33,650	31,725	31,601
Cost of revenues
Share-Based Compensation
Stock-based compensation expense	4,665	4,478	5,467
Research and development
Share-Based Compensation
Stock-based compensation expense	5,114	3,934	3,341
Selling, general and administrative
Share-Based Compensation
Stock-based compensation expense	$ 23,871	$ 23,313	$ 22,793

STOCK PLANS (Details 3)

STOCK PLANS (Details 3) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation arrangement by Share-based payment award, equity instruments others than options, vested and expected to vest, weighted average grant date fair value	$ 41.87
share-based compensation arrangement by share-based payment award, equity instruments other than options, vested and expected to vest, aggregate intrinsic value	$ 28,591
Stock options
Number of Shares
Balance at the beginning of the period (in shares)	5,722,818	4,951,493	5,207,743
Granted (in shares)	1,872,758	1,994,332	1,072,625
Exercised (in shares)	(425,495)	(332,732)	(539,989)
Forfeited (in shares)	(286,779)	(481,126)	(555,897)
Expired (in shares)	(176,924)	(409,149)	(232,989)
Balance at the end of the period (in shares)	6,706,378	5,722,818	4,951,493	5,207,743
Exercisable at the end of the period (in shares)	3,536,615
Vested and expected to vest at the end of the period (in shares)	6,706,378
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 41.69	$ 43.51	$ 42.16
Granted (in dollars per share)	42.75	39.35	43.93
Exercised (in dollars per share)	19.90	21.55	12.55
Forfeited (in dollars per share)	39.22	42.30	48.66
Expired (in dollars per share)	63.33	68.01	74.65
Balance at the end of the period (in dollars per share)	42.80	$ 41.69	$ 43.51	$ 42.16
Exercisable at the end of the period (in dollars per share)	44.02
Vested and expected to vest at the end of the period (in dollars per share)	$ 42.80
Weighted Average remaining contractual term
Balance at the end of the period	7 years 18 days	7 years 25 days	6 years 10 months 28 days	7 years 4 months 20 days
Exercisable at the end of the period	5 years 5 months 12 days
Vested and expected to vest at the end of the period	7 years 18 days
Aggregate intrinsic value
Balance at the beginning of the period (in dollars)	$ 49,166	$ 57,021	$ 37,581
Exercised (in dollars)	9,441	7,418	15,865
Balance at the end of the period (in dollars)	50,652	$ 49,166	$ 57,021	$ 37,581
Exercisable at the end of the period (in dollars)	37,569
Vested and expected to vest at the end of the period (in dollars)	$ 50,652
Weighted average assumptions used to estimate the fair values of each option grant
Risk free interest rate, minimum (as a percent)	1.33%	2.26%	1.68%
Risk free interest rate, maximum (as a percent)	2.54%	3.05%	2.42%
Expected volatility (as a percent)	53.90%	53.30%	51.40%
Expected life of options	5 years 2 months 19 days	5 years 1 month 20 days	5 years 3 months 21 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 20.92	$ 19.34	$ 20.78
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	577,964	499,546	364,403
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	305,418	331,129	343,583
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(192,760)	(156,450)	(101,379)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(59,481)	(96,261)	(107,061)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	631,141	577,964	499,546	364,403
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 42.14	$ 47.32	$ 52.85
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	43.56	38.36	44.23
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	45.55	49.59	53.76
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	41.22	43.92	49.98
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 41.87	$ 42.14	$ 47.32	$ 52.85
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding	$ 28,591	$ 24,864	$ 22,804	$ 11,824
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Vested and Expected to Vest	631,141,000
Stock options
Weighted average assumptions used to estimate the fair values of each option grant
Expected volatility (as a percent)	40.20%	52.20%	53.80%
Expected life of options	6 months	6 months	6 months
Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 11.13	$ 10.40	$ 13.85
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.10%	2.14%	1.14%
Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 11.36	$ 13.15	$ 10.80
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.56%	1.53%	0.62%

NET INCOME (LOSS) PER SHARE (De

NET INCOME (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Diluted									41,513	40,911	39,806
Numerator:
Net loss	$ (4,888)	$ (6,087)	$ 2,730	$ (2,771)	$ 8,285	$ (640)	$ 2,564	$ (10,680)	$ (11,016)	$ (471)	$ (42,611)
Basic and diluted net income (loss) per common share (in dollars per share)					$ 0.20	$ (0.02)	$ 0.06	$ (0.26)	$ (0.27)	$ (0.01)	$ (1.07)

NET INCOME (LOSS) PER SHARE (_2

NET INCOME (LOSS) PER SHARE (Details 2) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive effect of securities (in shares)	7,044	6,065	6,060
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive effect of securities (in shares)	6,404	5,492	5,171
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive effect of securities (in shares)	606	542	449
Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive effect of securities (in shares)	0	0	411
ESPP purchase options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive effect of securities (in shares)	34	31	29

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 13, 2017
Income Tax Provision [Line Items]
Domestic	$ (71)	$ 5,169	$ (39,898)
Foreign	(10,677)	(5,594)	(2,573)
Total loss before income taxes	(10,748)	(425)	(42,471)
Federal	0	(96)	0
State	2,096	142	140
Total current taxes	2,096	46	140
Federal	(1,828)	0	0
Total deferred taxes	(1,828)	0	0
Total income tax expense	$ 268	$ 46	$ 140
Reconciliation of income taxes at U.S. Federal statutory rate to the provision for income taxes
U.S. federal statutory rate	21.00%	21.00%	35.00%
State taxes	(7.33%)	(24.84%)	2.26%
Foreign taxes	(3.95%)	(92.04%)	(1.28%)
Change in valuation allowance	19.76%	369.27%	4.58%
Stock-based compensation	(10.53%)	(874.29%)	(1.21%)
Tax credits	19.93%	700.35%	4.96%
Interest expense	0.00%	218.47%	2.90%
Effect of rate changes	(0.42%)	13.44%	(130.88%)
Convertible senior notes refinancing	0.00%	0.00%	6.55%
Effect of the adoption of ASU 2016-09	0.00%	0.00%	68.89%
Nondeductible expenses	(13.58%)	(132.96%)	0.00%
Reserves	(15.41%)	(202.98%)	(2.47%)
Tax impact of MyoScience Acquisition	(9.61%)	0.00%	0.00%
Other	(2.35%)	(6.15%)	10.37%
Effective tax rate	(2.49%)	(10.73%)	(0.33%)
Deferred tax assets:
Net operating loss carry-forwards	$ 66,638	$ 79,446
Federal and state credits	16,895	17,730
Depreciation and amortization	16,541	2,851
Accruals and reserves	8,756	11,009
Stock based compensation	21,663	18,302
Inventory	1,542	848
Other	2,022	127
Total deferred tax assets	134,057	130,313
Discount on convertible senior notes	(8,383)	(11,655)
Net deferred tax assets, before valuation allowance	125,674	118,658
Less: valuation allowance	(125,674)	(118,658)
Net deferred tax assets	0	0
Non-US Net Operating Loss	$ 13,600
Minimum Cumulative Percentage of Change in Ownership as Condition to Offset Taxable Income or Tax	50.00%
Increase in valuation allowance for deferred tax assets	$ (7,000)	$ 1,600
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit)	$ 55,700
United States Statutory Tax Rate	21.00%	21.00%	35.00%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits	$ 2,881
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	1,656
Unrecognized Tax Benefits	4,537	$ 2,881
Convertible Senior Notes Due 2022 [Member]
Deferred tax assets:
Debt Instrument, Convertible, Carrying Amount of Equity Component				$ 70,900
Federal
Deferred tax assets:
Net operating losses	288,600
Net Operating Loss, Subject to Limitation	181,000
Available Net Operating Loss, Subject to Limitation	108,000
Future NOL's Which Will Become Available (2019-2022)	10,300
Future NOL's Which Will Become Available (2023)	3,500
Future NOL's Which Will Become Available (2024-2025)	1,400
Future NOL's Expired and Unused	35,800
State
Deferred tax assets:
Net operating losses	161,900
Research Tax Credit Carryforward [Member] | Federal
Deferred tax assets:
Tax Credit Carryforward, Amount	11,800
Research Tax Credit Carryforward [Member] | State
Deferred tax assets:
Tax Credit Carryforward, Amount	6,400
Myoscience Acquisition
Deferred tax assets:
Increase in valuation allowance for deferred tax assets	$ (1,800)

OTHER EMPLOYEE BENEFITS (Detail

OTHER EMPLOYEE BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Savings Plan
Compensation expense recognized	$ 2.6	$ 1.6	$ 1.3

ACQUISITION-RELATED CHARGES A_3

ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Non-recurring charge related to discontinuation		$ 200	$ 1,600	$ 5,400
Payments for settlement		5,300
Business Exit Costs		(1,515)	$ 13	$ 567
Myoscience Acquisition
Business Acquisition [Line Items]
Acquisition-related costs		21,600
Advisory Costs | Myoscience Acquisition
Business Acquisition [Line Items]
Acquisition-related costs		4,200
Separation Costs, Asset Write-downs, and Other Restructuring Charges | Myoscience Acquisition
Business Acquisition [Line Items]
Acquisition-related costs		700
Accounting Standards Update 2016-02
Business Acquisition [Line Items]
Business Exit Costs	$ (1,500)
Contingent Consideration [Member]
Business Acquisition [Line Items]
Fair value adjustments		$ 16,672

ACQUISITION-RELATED CHARGES A_4

ACQUISITION-RELATED CHARGES AND PRODUCT DISCONTINUATION, NET - DepoCyte Product Discontinuance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
DepoCyte Discontinuation [Roll Forward]
Acquisition-Related Separation Costs, Beginning Balance	$ 0	$ 0	$ 0
Acquisition-Related Separation Costs, Charges Incurred	429	0	303
Acquisition-Related Separation Costs, Cash Payments Made	(348)	0	(303)
Acquisition-Related Separation Costs, Ending Balance	81	0	0
DepoCyt(e) Lease Costs, Beginning Balance	1,970	1,768	0
DepoCyt(e) Lease Costs, Charges Incurred	0	1,513	(2,018)
DepoCyt(e) Lease Costs, Cash Payments Made	0	(1,311)	(744)
DepoCyt(e) Lease Costs, Balance Sheet Classifications	(1,970)	0	494
DepoCyt(e) Lease Costs, Ending Balance	0	1,970	1,768
Discontinued Operations - Fixed Asset and Inventory Writedown	193		2,470
Discontinued Operations Assets removed from Service	(193)		(2,470)
Asset Retirement Obligations, Other Restructuring and Discontinuation Costs, Beginning Balance	282	309	0
Asset Retirement Obligations, Other Restructuring and Discontinuation Costs, Charges Incurred	225	51	656
Asset Retirement Obligations, Other Restructuring and Discontinuation Costs, Cash Payments Made	(404)	(91)	(420)
Asset Retirement Obligation, Other Period Increase (Decrease)	0
Asset Retirement Obligations, Other Restructuring and Discontinuation Costs, Reclassifications	455	13	73
Asset Retirement Obligations, Other Restructuring and Discontinuation Costs, Ending Balance	558	282	309
Total, Beginning Balance	2,252	2,077	0
Total, Charges Incurred	847	1,564	5,447
Total, Cash Payments Made	752	(1,402)	(1,467)
Total, Other, Including Non-Cash Activity	(193)
Total, Reclassifications	(1,515)	13	567
Total, Ending Balance	$ 639	$ 2,252	$ 2,077

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - Member of board of directors - USD ($)	1 Months Ended		12 Months Ended
	Aug. 31, 2012	Apr. 30, 2012	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
RELATED PARTY TRANSACTIONS
Due to Related Parties			$ 0	$ 0
Consulting agreement
RELATED PARTY TRANSACTIONS
Number of shares that can be purchased under option (in shares)	70,000	20,000
Exercise price of shares that can be purchased under option (in dollars per share)	$ 16.67	$ 11.02
Consulting agreement | Maximum
RELATED PARTY TRANSACTIONS
Expenses incurred by the entity			$ 0	$ 0	$ 0

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	Mar. 21, 2007	Dec. 31, 2019	Dec. 31, 2018
Long-term Purchase Commitment [Line Items]
Litigation Settlement, Amount Awarded to Other Party		$ 3,500
Annual minimum payments due
2018			$ 8,140
2019			7,621
2020			5,295
2021			5,417
2022			5,543
2024 through 2028			14,329
Total			$ 46,345
Service [Member]
Annual minimum payments due
Purchase Obligation		25,500
Raw Materials [Member]
Annual minimum payments due
Purchase Obligation		300
PPI-California
Long-term Purchase Commitment [Line Items]
Initial purchase price for acquisition	$ 19,600
SkyePharma Holding, Inc.
Long-term Purchase Commitment [Line Items]
Total milestone payments paid		36,000
SkyePharma Holding, Inc. | Maximum
Long-term Purchase Commitment [Line Items]
Milestone payments for EXPAREL agreed in connection with acquisition		$ 62,000

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES (Details 2) - USD ($) $ in Millions	Mar. 21, 2007	Dec. 31, 2019
SkyePharma Holding, Inc.
Commitments
Total milestone payments paid		$ 36
SkyePharma Holding, Inc. | Maximum
Commitments
Milestone payments for EXPAREL agreed in connection with acquisition		$ 62
PPI-California
Commitments
Initial purchase price for acquisition	$ 19.6

SELECTED QUARTERLY FINANCIAL _3

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 122,424	$ 104,685	$ 102,604	$ 91,313	$ 95,115	$ 83,448	$ 84,107	$ 74,607	$ 421,026	$ 337,277	$ 286,630
Cost of goods sold	31,904	22,304	25,201	27,303	23,979	19,065	20,916	22,885	106,712	86,845	87,915
Total operating expenses	120,711	102,272	97,329	90,234	82,852	79,400	77,566	81,544	410,546	321,362	311,567
Net loss	$ (4,888)	$ (6,087)	$ 2,730	$ (2,771)	$ 8,285	$ (640)	$ 2,564	$ (10,680)	$ (11,016)	$ (471)	$ (42,611)
Basic and diluted net income (loss) per common share (in dollars per share)	$ (0.12)	$ (0.15)	$ 0.06	$ (0.07)
Earnings Per Share, Basic	$ (0.12)	$ (0.15)	$ 0.07	$ (0.07)

COMMERCIAL PARTNERS AND OTHER_2

COMMERCIAL PARTNERS AND OTHER AGREEMENTS (Details) - USD ($) $ in Millions	Jul. 20, 2018	Dec. 05, 2012	Aug. 31, 2016	Jun. 30, 2016	Dec. 31, 2013	Jun. 19, 2018
Aratana Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative Arrangement, Upfront Payment Received		$ 1
Collaborative Arrangement, Milestone Payments Received			$ 1	$ 1	$ 0.5
Nuance Biotech Co. Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative Arrangement, Upfront Payment Received	$ 3
Achievement of Development and Commercial Milestones [Member] | Maximum | Aratana Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative Arrangement, Milestone Payments to be Received		$ 40
Achievement of Development and Commercial Milestones [Member] | Maximum | Nuance Biotech Co. Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative Arrangement, Milestone Payments to be Received						$ 60

Uncategorized Items - pcrx-1231

Label	Element	Value
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 287,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (287,000)