Assertio (ASRT) 10-K 12 Mar 21 2020 FY Annual report Financial data

Cover

Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Mar. 01, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39294
Entity Registrant Name	ASSERTIO HOLDINGS, INC.
Entity Central Index Key	0001808665
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-0598378
Entity Address, Address Line One	100 South Saunders Road
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Lake Forest
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60045
City Area Code	224
Local Phone Number	419‑7106
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	ASRT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 89.9
Entity Common Stock, Shares Outstanding		173,436,800
Documents Incorporated by Reference	Part III of this Annual Report on Form 10-K incorporates by reference portions of the registrant’s Proxy Statement for its 2021 Annual Meeting of Stockholders, which Proxy Statement will be filed with the United States Securities and Exchange Commission within 120 days after the end of the registrant’s 2020 fiscal year.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 20,786	$ 42,107
Accounts receivable, net	44,350	42,744
Inventories, net	11,712	3,412
Prepaid and other current assets	17,406	15,688
Total current assets	94,254	103,951
Property and equipment, net	2,437	3,497
Intangible assets, net	200,082	400,535
Investments, net	1,579	13,064
Other long-term assets	4,922	6,123
Total assets	303,274	527,170
Current liabilities:
Accounts payable	14,808	16,193
Accrued rebates, returns and discounts	63,114	58,943
Accrued liabilities	31,571	18,948
Current portion of long-term debt	11,942	80,000
Contingent consideration, current portion	6,776	0
Interest payable	1,793	8,375
Other current liabilities	2,682	2,094
Total current liabilities	132,686	184,553
Long-term debt	72,160	271,258
Contingent consideration	31,776	168
Other long-term liabilities	11,138	13,233
Total liabilities	247,760	469,212
Commitments and contingencies
Shareholders’ equity:
Common stock, $0.0001 par value, 200,000,000 shares authorized; 113,568,597 and 80,888,134 shares issued and outstanding as of December 31, 2020 and 2019, respectively	13	8
Additional paid-in capital	483,446	457,751
Accumulated deficit	(427,945)	(399,801)
Total shareholders’ equity	55,514	57,958
Total liabilities and shareholders' equity	$ 303,274	$ 527,170

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares outstanding (in shares)	113,568,597	80,888,134
Common stock, shares issued (in shares)	113,568,597	80,888,134

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Total revenues	$ 106,275	$ 229,504
Costs and expenses:
Cost of sales (excluding amortization of intangible assets)	19,872	9,505
Research and development expenses	4,213	10,106
Selling, general and administrative expenses	104,324	108,866
Amortization of intangible assets	24,783	101,774
Loss on impairment of goodwill and intangible assets	17,432	189,790
Restructuring charges	17,806	3,891
Total costs and expenses	188,430	423,932
Loss from operations	(82,155)	(194,428)
Other income (expense):
(Loss) Gain on debt extinguishment	(56,113)	26,385
Interest expense	(15,926)	(58,389)
Other (loss) gain	(3,225)	3,948
Total other income (expense)	36,642	(28,056)
Net loss before income taxes	(45,513)	(222,484)
Income tax benefit	17,369	5,283
Net loss	(28,144)	(217,201)
Comprehensive loss	$ (28,144)	$ (217,201)
Basic net loss per share (in dollars per share)	$ (0.27)	$ (3.07)
Diluted net loss per share (in dollars per share)	$ (0.27)	$ (3.07)
Shares used in computing basic net loss per share (in shares)	104,835	70,716
Shares used in computing diluted net loss per share (in shares)	104,835	70,716
Product sales, net
Revenues:
Total revenues	$ 93,498	$ 108,806
Commercialization agreement, net
Revenues:
Total revenues	11,258	118,614
Royalties and milestones
Revenues:
Total revenues	1,519	2,084
NUCYNTA
Other income (expense):
Gain (loss) on sale	(14,749)	0
Gralise
Revenues:
Total revenues	300	63,100
Other income (expense):
Gain (loss) on sale	$ 126,655	$ 0

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Earnings (Deficit)	Accumulated Other Comprehensive Loss	Convertible debt	Convertible debtAdditional Paid-In Capital	Convertible debtConvertible Senior Notes, 2.5%	Convertible debtConvertible Senior Notes, 2.5%Additional Paid-In Capital	Convertible debtConvertible Senior Notes, 5.0%	Convertible debtConvertible Senior Notes, 5.0%Additional Paid-In Capital
Balances at Dec. 31, 2018	$ 220,335	$ 6	$ 402,934	$ (182,600)	$ (5)
Balances (in shares) at Dec. 31, 2018		64,185,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of options	$ 25		25
Issuance of common stock upon exercise of options (in shares)	0	14,000
Issuance of common stock under employee stock purchase plan	$ 226		226
Issuance of common stock under employee stock purchase plan (in shares)		169,000
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		703,000
Issuance of common stock in conjunction with the Convertible Note Exchange (in shares)		15,817,000
Issuance of common stock in conjunction with the Convertible Note Exchange	25,307	$ 2	25,305
Reacquisition of equity component of notes								$ (4,763)	$ (4,763)
Equity component of issued 2024 Notes, net of tax benefit of $7,212								6,200		$ 23,999	$ 23,999
Stock-based compensation	10,596		10,596
Shares withheld for payment of employees' tax liability	(571)		(571)
Unrealized gain on available-for-sale securities	5				5
Net income (loss)	(217,201)			(217,201)
Balances at Dec. 31, 2019	$ 57,958	$ 8	457,751	(399,801)	0
Balances (in shares) at Dec. 31, 2019	80,888,134	80,888,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of options (in shares)	0
Issuance of common stock under employee stock purchase plan	$ 87		87
Issuance of common stock under employee stock purchase plan (in shares)		183,000
Issuance of common stock in conjunction with vesting of restricted stock units		$ 1				$ 1
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		934,000
Issuance of common stock upon exercise of warrant		6,085,000
Issuance of common stock upon exercise of warrant (in shares)	0	$ 1	(1)
Issuance of common stock in connection with Zyla Merger (in shares)		25,479,000
Issuance of common stock in connection with Zyla Merger	22,931	$ 3	22,928
Issuance of warrants and stock options in connection with Zyla Merger	11,626		11,626
Reacquisition of equity component of notes						$ (19,532)	$ (19,532)	$ (300)
Stock-based compensation	10,924		10,924
Shares withheld for payment of employees' tax liability	(337)		(337)
Net income (loss)	(28,144)			(28,144)
Balances at Dec. 31, 2020	$ 55,514	$ 13	$ 483,446	$ (427,945)	$ 0
Balances (in shares) at Dec. 31, 2020	113,568,597	113,569,000

CONSOLIDATED STATEMENTS OF SH_2

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - Convertible debt $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Convertible Senior Notes, 2.5%
Equity component, tax loss (benefit)	$ 1,445
Convertible Senior Notes, 5.0%
Equity component, tax loss (benefit)	$ (7,212)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Operating Activities
Net loss	$ (28,144)	$ (217,201)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	26,431	102,946
Amortization of debt discount and debt issuance costs	5,680	23,764
Stock-based compensation	10,924	10,596
Provisions for inventory and other assets	3,817	5,304
Impairment of goodwill and intangible assets	17,432	189,790
Loss on disposal of equipment and early termination of leases	1,588	10,076
Income tax provision	(8,424)	(5,767)
Gain (loss) on extinguishment and prepayment of debt	56,113	(26,385)
Recurring fair value measurement of assets and liabilities	5,129	(1,715)
Other	0	(327)
Changes in assets and liabilities:
Accounts receivable	19,800	(5,533)
Inventories	(291)	(316)
Prepaid and other assets	10,797	40,769
Income taxes receivable	(8,973)	0
Accounts payable and other accrued liabilities	(28,569)	(15,440)
Accrued rebates, returns and discounts	(29,066)	(16,816)
Interest payable	(7,910)	(3,270)
Net cash (used in) provided by operating activities	(65,572)	90,475
Investing Activities
Cash acquired in Zyla Merger	7,585	0
Proceeds from sale of investments	6,000	0
Purchases of property and equipment	(10)	(1,481)
Purchases of marketable securities	0	(12,065)
Maturities of marketable securities	0	4,209
Sales of marketable securities	0	7,856
Net cash provided by (used in) investing activities	512,801	(1,481)
Financing Activities
Payments in connection with debt extinguishment	(264,731)	(30,000)
Repayment of Senior Notes	(171,775)	(120,000)
Payment in connection with 13% Senior Secured Notes	(14,750)	0
Payments on Revolver	(10,000)	0
Payment of contingent consideration liability	(3,016)	0
Payments on Promissory Note	(3,000)	0
Payment of royalty rights obligation	(500)	0
Payment of employees' tax liability related to common shares withheld	(866)	(570)
Convertible notes issuance costs	0	(4,268)
Fees for modification of Senior Notes	0	(3,249)
Proceeds from issuance of common stock	88	251
Net cash used in financing activities	(468,550)	(157,836)
Net decrease in cash and cash equivalents	(21,321)	(68,842)
Cash and cash equivalents at beginning of year	42,107	110,949
Cash and cash equivalents at end of period	20,786	42,107
Supplemental Disclosure of Cash Flow Information
Net cash refund of (paid for) income taxes	1,136	(4,401)
Cash paid for interest	17,598	37,788
Capital expenditures incurred but not yet paid	0	500
Convertible debt
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of debt discount and debt issuance costs	1,550	15,398
Gain (loss) on extinguishment and prepayment of debt	47,880	(26,385)
Senior Notes
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of debt discount and debt issuance costs	2,699	5,783
Gain (loss) on extinguishment and prepayment of debt	8,233	0
Financing Activities
Payments in connection with debt extinguishment	$ (4,900)
Senior Notes | 13% Senior Secured Note due 2024
Supplemental Disclosure of Cash Flow Information
Interest rate	13.00%
Gralise
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Gain (loss) on sale	$ (126,655)	0
Investing Activities
Proceeds from sale	130,261	0
NUCYNTA
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Gain (loss) on sale	14,749	0
Investing Activities
Proceeds from sale	$ 368,965	$ 0

ORGANIZATION AND SUMMARY OF SIG

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization On May 20, 2020, Assertio Holdings, Inc. completed a merger (Zyla Merger) with Zyla Life Sciences (Zyla) pursuant to an Agreement and Plan of Merger (Merger Agreement), dated as of March 16, 2020. Prior to the consummation of the Zyla Merger, Assertio Therapeutics, Inc. (which changed its name from Depomed, Inc. in August 2018) implemented a holding company reorganization (Assertio Reorganization) pursuant to an Agreement and Plan of Merger, dated as of May 19, 2020, by and among Assertio Therapeutics, Inc., Assertio Holdings, Inc. and a wholly-owned subsidiary formed to effectuate the Assertio Reorganization. As a result of the Assertio Reorganization, Assertio Therapeutics, Inc. became a direct, wholly-owned subsidiary of Assertio Holdings, Inc. and e ach issued and outstanding share of common stock, $0.0001 par value per share, of Assertio Therapeutics, Inc. immediately prior to the Assertio Reorganization automatically converted into an equivalent corresponding share of common stock, $0.0001 par value per share, of Assertio Holdings, Inc. having the same designations, rights, powers, preferences, qualifications, limitations and restrictions as the converted share of Assertio Therapeutics, Inc. common stock. Unless otherwise noted or required by context, use of “Assertio” and “Company” refer to Assertio Therapeutics, Inc. any time prior to the Assertio Reorganization and to Assertio Holdings, Inc. following the Assertio Reorganization. Assertio is a commercial pharmaceutical company offering differentiated products to patients. The Company’s commercial portfolio of branded products focuses on three areas: neurology, hospital, and pain and inflammation. The Company has built its commercial portfolio through a combination of increased opportunities with existing products, as well as through the acquisition or licensing of additional approved products. The Company’s marketed products are: INDOCIN ® (indomethacin) Suppositories A suppository form and oral solution of indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), approved for: • Moderate to severe rheumatoid arthritis including acute flares of chronic disease • Moderate to severe ankylosing spondylitis INDOCIN ® (indomethacin) Oral Suspension • Moderate to severe osteoarthritis • Acute painful shoulder (bursitis and/or tendinitis) • Acute gouty arthritis CAMBIA ® (diclofenac potassium for oral solution) A prescription medicine used to treat migraine attacks in adults. CAMBIA does not prevent or lessen the number of migraines one has, and it is not for other types of headaches. It contains diclofenac potassium, a non-steroidal anti-inflammatory drug (NSAID). SPRIX ® (ketorolac tromethamine) Nasal Spray A prescription NSAID indicated in adult patients for the short term (up to five days) management of moderate to moderately severe pain that requires analgesia at the opioid level. Zipsor ® (diclofenac potassium) Liquid filled capsules A prescription NSAID used for relief of mild-to-moderate pain in adults (18 years of age and older) Other commercially available products include ZORVOLEX® (diclofenac) and VIVLODEX® (meloxicam) (collectively known as the SOLUMATRIX® products), as well as OXAYDO® (oxycodone HCI, USP) tablets for oral use only —CII. In September 2020, the Company terminated its Second Amended and Restated Nano-Reformulated Compound License Agreement as of January 27, 2020 (the “iCeutica License”), with iCeutica Inc. and iCeutica Pty Ltd. (collectively, “iCeutica”). The iCeutica License allowed the Company to utilize certain technology and intellectual property related to iCeutica’s SOLUMATRIX technology and certain other rights of iCeutica. Accordingly, the intellectual property related to SOLUMATRIX technology will no longer be used by the Company and the Company will no longer manufacture products using SOLUMATRIX technology. On February 13, 2020, the Company completed the sale of its remaining rights, title and interest in and to the NUCYNTA® franchise to Collegium Pharmaceutical, Inc. (Collegium) for $375.0 million, less royalties, in cash at closing. Collegium assumed certain contracts, liabilities and obligations relating to the NUCYNTA products, including those related to manufacturing and supply, post-market commitments and clinical development costs. Collegium also paid for certain inventories relating to the products. On January 10, 2020, the Company completed the sale of Gralise ® (gabapentin) to Golf Acquiror LLC, an affiliate to Alvogen, Inc. (Alvogen), for cash proceeds of $130.3 million. The total value included $75.0 million in cash at closing, with the balance receivable as 75% of Alvogen’s first $70.0 million of Gralise net sales after the closing (consideration receivable). Alvogen also paid for certain inventories relating to Gralise. On June 3, 2020, the Company entered into an agreement with Alvogen to settle the remaining balance of $39.7 million in consideration receivable, whereby the Company reduced the consideration receivable by $0.9 million and Alvogen paid $38.8 million in cash. Basis of Preparation The Company’s consolidated financial statements are prepared in accordance with United States (“U.S.”) generally accepted accounting principles (U.S. GAAP) and U.S. Securities and Exchange Commission (SEC) regulations for annual reporting. In connection with the preparation of the financial statements for the year ended December 31, 2020, the Company evaluated whether there were conditions and events, considered in the aggregate, which raised substantial doubt as to the entity's ability to continue as a going concern within twelve months after the date of the issuance of these financial statements noting that there did not appear to be evidence of substantial doubt of the entity's ability to continue as a going concern. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Estimates are used when accounting for amounts recorded in connection with acquisitions, including initial fair value determinations of assets and liabilities as well as subsequent fair value measurements. Additionally, estimates are used in determining items such as sales discounts and returns, depreciable and amortizable lives, share-based compensation assumptions and taxes on income. Although management believes these estimates are based upon reasonable assumptions within the bounds of its knowledge of the Company, actual results could differ materially from these estimates. Segment Information The Company manages its business within one reportable segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. To date, substantially all of the Company’s revenues from product sales are related to sales in the U.S. Cash, Cash Equivalents Cash and cash equivalents include cash in readily available checking and money market funds. We consider all highly liquid investments purchased with a maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents are carried at cost, which approximates fair value. Accounts Receivable Trade accounts receivable are recorded net of allowances for cash discounts for prompt payment. To date the Company has not recorded a bad debt allowance since the majority of its product revenue comes from sales to a limited number of financially sound companies who have historically paid their balances timely. The need for a bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers or any other potential circumstances that could result in bad debt. Inventories Inventories are stated at the lower of cost or net realizable value with cost determined by specific manufactured lot. Inventories consist of costs of the active pharmaceutical ingredient, contract manufacturing and packaging costs. Additionally, the Company writes off the value of inventory for potentially excess, dated or obsolete inventories based on an analysis of inventory on hand and projected demand. Cost of sales includes the cost of inventory sold or reserved, which includes manufacturing and supply chain costs, product shipping and handling costs, and product royalties. Investments Assertio received warrants to purchase Collegium stock in conjunction with its November 2018 amendment to the Collegium Commercialization Agreement. Such warrants were measured at fair value with changes in fair value recorded in Other (loss) gain on the Company’s Consolidated Statements of Comprehensive Income during the year ended December 31, 2019. The Collegium warrants were sold during the year ended December 31, 2020. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets, as follows: Furniture and office equipment 3 - 5 years Machinery and equipment 5 - 7 years Laboratory equipment 3 - 5 years Leasehold improvements Shorter of estimated useful life or lease term Intangible Assets (other than goodwill) Intangible assets, other than goodwill, consist of product rights that are accounted for as definite-lived intangible assets subject to amortization. The Company determines the fair value of acquired intangible assets as of the acquisition date. Discounted cash flow models are typically used in these valuations, which require the use of significant estimates and assumptions, including but not limited to, developing appropriate discount rates and estimating future cash flows from product sales and related expenses. The fair value recorded is amortized on a straight-line basis over the estimated useful life of the asset. The Company estimated the useful life of the assets by considering competition by products prescribed for the same indication, the likelihood and estimated future entry of non-generic and generic competition for the same or similar indication and other related factors. Impairment of Long-lived Assets The Company evaluates long-lived assets, including property and equipment and product rights, for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss is calculated as the excess of the carrying amount over the fair value. Estimating future cash flows and fair value related to an intangible asset involves significant estimates and assumptions. If the Company’s assumptions are not correct, there could be an impairment loss or, in the case of a change in the estimated useful life of the asset, a change in amortization expense. As of December 31, 2020, the Company determined there were indicators of impairment present related to the declining revenues due to the adverse impact of COVID-19 on our business as well as unfavorable changes in product payor mix, resulting in the Company’s announcement of the December 2020 Plan. These factors contributed to higher operating losses and cash used by operating activities during the year ended December 31, 2020, as compared to the prior year. In addition, during the fourth quarter of 2020, the Company’s market capitalization declined from approximately $72.0 million as of September 30, 2020 to $38.0 million as of December 31, 2020. As a result of these recent events, the Company determined indicators of impairment were present and, accordingly, performed a test for recoverability of long-lived assets to be held and used pursuant to ASC 360, Impairment Testing: Long Lived Assets Classified as Held and Used. After grouping the long-lived assets, including purchased developed technology and trademarks, at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other assets and liabilities, the Company estimated the future net undiscounted cash flows expected to be generated from the use of the long-lived asset group and its eventual disposition. The Company then compared the estimated undiscounted cash flows to the carrying amount of the long-lived asset group. Based on this test, the Company determined that the estimated undiscounted cash flows were in excess of the carrying amount of the long-lived asset group and, accordingly, the long-lived asset group is fully recoverable. Acquisitions The Company accounts for acquired businesses using the acquisition method of accounting under ASC 805, Business Combinations (ASC 805), which requires that assets acquired and liabilities assumed be recorded at date of acquisition at their respective fair values. The fair value of the consideration paid, including contingent consideration, is assigned to the underlying net assets of the acquired business based on their respective fair values. Any excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Significant judgments are used in determining the estimated fair values assigned to the assets acquired and liabilities assumed and in determining estimates of useful lives of long-lived assets. Fair value determinations and useful life estimates are based on, among other factors, estimates of expected future net cash flows, estimates of appropriate discount rates used to present value expected future net cash flows, the assessment of each asset’s life cycle, and the impact of competitive trends on each asset’s life cycle and other factors. These judgments can materially impact the estimates used to allocate acquisition date fair values to assets acquired and liabilities assumed and the resulting timing and amounts charged to, or recognized in current and future operating results. For these and other reasons, actual results may vary significantly from estimated results. Any changes in the fair value of contingent consideration resulting from a change in the underlying inputs is recognized in operating expenses until the contingent consideration arrangement is settled. Changes in the fair value of contingent consideration resulting from the passage of time are recorded within interest expense until the contingent consideration is settled. If the acquired net assets do not constitute a business under the acquisition method of accounting, the transaction is accounted for as an asset acquisition and no goodwill is recognized. In an asset acquisition, the amount allocated to acquired in-process research and development with no alternative future use is charged to expense at the acquisition date. Goodwill Under the purchase method of accounting pursuant to ASC 805 , Goodwill is calculated as the excess of the purchase price over the fair value of the assets acquired and liabilities assumed. Goodwill, which is not tax-deductible, is recognized within other long-term assets, and is not amortized but subject to an annual review for impairment. Goodwill is tested for impairment at the reporting unit level at least annually or when a triggering event occurs that could indicate a potential impairment by assessing qualitative factors or performing a quantitative analysis in determining whether it is more likely than not that the fair value of net assets are below their carrying amounts. A reporting unit is the same as, or one level below, an operating segment. Our operations are currently comprised of a single reporting unit. As of December 31, 2020, the Company determined, due to declining revenues and a decrease in its market capitalization, that it was more likely than not that the fair value of net assets are below their carrying amounts and, therefore, the Company performed the required goodwill impairment test under ASC 350, I ntangibles - Goodwill and Other . First, the Company estimated the fair value of the reporting unit to which goodwill is assigned using a combination of the income and market approach. The Company then compared the carrying amount of the reporting unit, including goodwill, to its fair value. Since the fair value was less than the reporting unit’s carrying amount, the Company calculated the goodwill impairment as the difference between the reporting unit’s fair value and the carrying amount, not to exceed the carrying amount of goodwill. Accordingly, the Company recorded an impairment charge of $17.4 million, recognized within total costs and expenses in the Consolidated Statement of Comprehensive Income, to impair the carrying amount of goodwill as of December 31, 2020. Contingent Consideration The Company assumed a contingent consideration liability upon its merger with Zyla. The liability assumed included contingent consideration related to royalties payable in the form of an earnout provision based on INDOCIN Product revenue estimates and a probability assessment with respect to the likelihood of achieving the level of net sales that would trigger the contingent payment. The fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement as defined in fair value measurement accounting. The key assumptions in determining the fair value are the discount rate and the probability assigned to the potential milestones being achieved. At each reporting date, the Company will re-measure the contingent consideration obligation to estimated fair value which is recognized as change in fair value of contingent consideration payable within operating expenses in the Company’s Consolidated Statements of Operations. Revenue Recognition Under ASC 606, Revenue from Contracts with Customers (ASC 606), the Company recognizes revenue when its customer obtains control of the promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation, when (or as) the performance obligation is satisfied. The Company assesses the term of the contract based upon the contractual period in which the Company and Collegium have enforceable rights and obligations. Variable consideration arising from sales or usage-based royalties, promised in exchange for a license of the Company’s Intellectual Property, is recognized at the later of (i) when the subsequent product sales occur or (ii) the performance obligation, to which some or all of the sales-based royalty has been allocated, has been satisfied. The Company recognizes a contract asset relating to its conditional right to consideration for completed performance obligations. Accounts receivable are recorded when the right to consideration becomes unconditional. A contract liability is recorded for payments received in advance of the related performance obligation being satisfied under the contract. Product Sales The Company sells commercial products to wholesale distributors and specialty pharmacies. Product sales revenue is recognized when title has transferred to the customer and the customer has assumed the risks and rewards of ownership, which typically occurs on delivery to the customer. The Company’s performance obligation is to deliver product to the customer, and the performance obligation is completed upon delivery. The transaction price consists of a fixed invoice price and variable product sales allowances, which include rebates, discounts and returns. Product sales revenues are recorded net of applicable sales tax and reserves for these product sales allowances. Receivables related to product sales are typically collected one Product Sales Allowances - The Company considers products sales allowances to be variable consideration and estimates and recognizes product sales allowances as a reduction of product sales in the same period the related revenue is recognized. Product sales allowances are based on actual or estimated amounts owed on the related sales. These estimates take into consideration the terms of the Company’s agreements with customers, historical product returns, rebates or discounts taken, estimated levels of inventory in the distribution channel, the shelf life of the product and specific known market events, such as competitive pricing and new product introductions. The Company uses the most likely method in estimating product sales allowances. If actual future results vary from the Company’s estimates, the Company may need to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustment. The Company’s sales allowances include: Product Returns - The Company allows customers to return product for credit with respect to that product within six months before and up to 12 months after its product expiration date. The Company estimates product returns and associated credit on Zipsor, CAMBIA, NUCYNTA, Gralise, Lazanda and products acquired from Zyla, INDOCIN Products, ZORVOLEX, VIVLODEX and OXAYDO. Estimates for returns are based on historical return trends by product or by return trends of similar products, taking into consideration the shelf life of the product at the time of shipment, shipment and prescription trends, estimated distribution channel inventory levels and consideration of the introduction of competitive products. The Company did not assume financial responsibility for returns of NUCYNTA previously sold by Janssen Pharma or Lazanda product previously sold by Archimedes Pharma US Inc. Under the Commercialization Agreement with Collegium for NUCYNTA, the divestiture of Lazanda to Slán and the divestiture of Gralise to Alvogen, the Company is only financially responsible for product returns for product that were sold by the Company, which are identified by specific lot numbers. Shelf lives, from the respective manufacture dates, for the Company’s products range from 24 months to 48 months. Because of the shelf life of the Company’s products and its return policy of issuing credits with respect to product that is returned within six months before and up to 12 months after its product expiration date, there may be a significant period of time between when the product is shipped and when the Company issues credit on a returned product. Accordingly, the Company may have to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustments. Wholesaler and Pharmacy Discounts—The Company offers contractually determined discounts to certain wholesale distributors and specialty pharmacies that purchase directly from it. These discounts are either taken off invoice at the time of shipment or paid to the customer on a quarterly basis one Prompt Pay Discounts - The Company offers cash discounts to its customers (generally 2% of the sales price) as an incentive for prompt payment. Based on the Company’s experience, the Company expects its customers to comply with the payment terms to earn the cash discount. Patient Discount Programs - The Company offers patient discount co-pay assistance programs in which patients receive certain discounts off their prescriptions at participating retail and specialty pharmacies. The discounts are reimbursed by the Company to program administrators approximately one month after the prescriptions subject to the discount are filled. Medicaid Rebates - The Company participates in Medicaid rebate programs, which provide assistance to certain low income patients based on each individual state’s guidelines regarding eligibility and services. Under the Medicaid rebate programs, the Company pays a rebate to each participating state, generally two Chargebacks - The Company provides discounts to authorized users of the Federal Supply Schedule (FSS) of the General Services Administration under an FSS contract with the Department of Veterans Affairs and 340B eligible entities. These federal and 340B entities purchase products from the wholesale distributors at a discounted price, and the wholesale distributors then charge back to the Company the difference between the current retail price and the price the federal entity paid for the product. Managed Care Rebates - The Company offers discounts under contracts with certain managed care providers. The Company generally pays managed care rebates one Medicare Part D Coverage Gap Rebates - The Company participates in the Medicare Part D Coverage Gap Discount Program under which it provides rebates on prescriptions that fall within the “donut hole” coverage gap. The Company generally pays Medicare Part D Coverage Gap rebates two Royalties and Milestone Revenue For arrangements that include sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company currently has the right to receive royalties based on sales of CAMBIA in Canada, which are recognized as revenue when the related sales occur as there are no continuing performance obligations by the Company under those agreements. For arrangements that include milestones, the Company recognizes such revenue using the most likely method. At the end of each reporting period, the Company re-evaluates the probability or achievement of any potential milestone and any related constraints, and if necessary, adjusts its estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue in the period of adjustment. Leases The Company adopted ASC 842, Leases (ASC 842), on January 1, 2019 using the modified retrospective approach. There was no adjustment to the Company's opening balance of accumulated deficit resulting from the adoption of this guidance. In addition, the Company elected the package of practical expedients, which among other things, allowed for the carryforward of the historical lease classification. The Company did not elect the hindsight practical expedient to determine the reasonably certain lease term for existing leases. Prior to the adoption of ASC 842, the Company accounted for its operating leases in accordance with ASC 840. Under ASC 840, only capital leases were recognized on the balance sheet and therefore the Company’s operating leases were reflected in the financial statement footnotes. The adoption of ASC 842 did not materially affect the Company’s Consolidated Comprehensive Income. The Company assesses contracts for lease arrangements at inception. Operating right-of-use (ROU) assets and liabilities are recognized at the lease commencement date equal to the present value of future lease payments using the implicit, if readily available, or incremental borrowing rate based on the information readily available at the commencement date. ROU assets include any lease payments as of commencement and initial direct costs but exclude any lease incentives. Lease and non-lease components are generally accounted for separately and the Company recognizes operating lease expense straight-line over the term of the lease. Operating leases are included in other long-term assets, other current liabilities other long term liabilities The Company accounts for operating leases with an initial term of 12 months or less on a straight-line basis over the lease term in the Consolidated Statements of Comprehensive Income. Stock Based Compensation The Company’s stock-based compensation generally includes stock options, restricted stock units (RSUs), performance share units (PSUs), and purchases under the Company’s employee stock purchase plan (ESPP). The Company accounts for forfeitures as they occur for each type of award. Stock-based compensation expense related to restricted stock unit awards (RSUs) is based on the market value of the underlying stock on the date of grant and the related expense is recognized ratably over the requisite service period. The stock-based compensation expense related to performance share units (PSUs) is estimated at grant date based on the fair value of the award. The PSU awards are measured exclusively to the relative total shareholder return (TSR) performance, which is measured against the three-year TSR of a custom index of companies. The actual number of shares awarded is adjusted to between zero and 200% of the target award amount based upon achievement in each of the three The Company uses the Black-Scholes option valuation model to determine the fair value of stock options and employee stock purchase plan (ESPP) shares. The determination of the fair value of stock-based payment awards on the date of grant using an option valuation model is affected by our stock price as well as assumptions, which include the expected term of the award, the expected stock price volatility, risk-free interest rate and expected dividends over the expected term of the award. The Company uses historical option exercise data to estimate the expected term of the options. The Company estimates the volatility of our common stock price by using the historical volatility over the expected term of the options. The Company bases the risk-free interest rate on U.S. Treasury zero coupon issues with terms similar to the expected term of the options as of the date of grant. The Company does not anticipate paying any cash dividends in the foreseeable future, and therefore, uses an expected dividend yield of zero in the option valuation model. Stock-based compensation expense related to the ESPP and options is recognized on a straight-line basis over its respective term. Research and Development Expense Research and development (R&D) expenses include salaries, clinical trial costs, consultant fees, supplies, manufacturing costs for research and development programs, allocations of corporate costs, as well as post-marketing clinical studies. All such costs are charged to R&D expense as incurred. These expenses result from the Company’s independent R&D efforts as well as efforts associated with collaborations. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical costs are subject to revisions as trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Advertising Costs Costs associated with advertising are expensed as incurred. Advertising expense for the years ended December 31, 2020 and 2019 were $0.4 million and $0.8 million, respectively. Restructuring Restructuring costs are included in Restructuring charges within the Consolidated Statements of Comprehensive Income. The Company has accoun

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Business Combination Zyla Life Sciences On May 20, 2020, Assertio completed the Zyla Merger pursuant to the Agreement and Plan of Merger dated March 16, 2020. Upon consummation of the Zyla Merger, each issued and outstanding share of Zyla common stock converted into 2.5 shares of Assertio Holding’s common stock (the Exchange Ratio), and each outstanding option or warrant to purchase Zyla common stock converted into the right to purchase shares of Assertio’s common stock. The company accounted for the Zyla Merger using the acquisition method of accounting under ASC 805. The following table reflects the acquisition date fair value of the consideration transferred with respect to the Zyla Merger: Total number of Company ordinary shares issued 25,478,539 Assertio share price as of May 20, 2020 $ 0.90 Fair value of common shares issued (in thousands) $ 22,931 Fair value of warrants and stock options issued (in thousands) (1) $ 11,626 Taxes paid by the Company on behalf of Zyla (in thousands) 529 Total purchase consideration (in thousands) $ 35,086 (1) Represents 4,972,365 of Zyla warrants outstanding as of May 20, 2020 at the Exchange Ratio or 12,430,913 Company warrants. The Company’s warrants were valued using the Company’s share price of $0.90 as of May 20,2020. As these shares are exercisable at any time at an exercise price of $0.0004 per share and Assertio issued replacement awards for these shares, these shares represent consideration transferred. Costs incurred that were directly attributable to facilitating the close of the Zyla Merger were $6.6 million and were recognized during the first six months of 2020. These costs were recorded to the Selling, general and administrative expenses in the Consolidated Statements of Comprehensive Income. Pursuant to ASC 805, one of the companies in the transactions shall be designated as the acquirer for accounting purposes based on the evidence available. For accounting purposes, Assertio was treated as the acquiring entity. The Zyla Merger transaction was accounted for as a business combination under the acquisition method of accounting in accordance with ASC 805. Under this method, the acquisition was recorded by allocating the purchase price consideration to the tangible and intangible assets acquired and liabilities assumed from Zyla, based on the estimated fair values at the acquisition date. The excess of purchase price over the fair value of the acquired net assets was recorded as goodwill. The results of operations of this transaction have been included in the Company’s consolidated financial statements from the date of acquisition. As of the merger date in 2020, valuations were performed to assess the fair value of certain assets acquired and liabilities assumed. Accounting guidance provides that the allocation of the purchase price may be modified up to one year from the date of the merger as more information is obtained about the fair value of assets acquired and liabilities assumed. The Company finalized the Zyla Merger purchase price allocation effective December 31, 2020. The following table reflects the initial preliminary and final fair values of the assets acquired and liabilities assumed, and measurement period adjustments during the year ended December 31, 2020, as of the acquisition date (in thousands): Initial Preliminary Purchase Price Allocation (PPA) to Fair Value Measurement period adjustments Final PPA to Fair Value Cash $ 7,585 $ — $ 7,585 Accounts receivable 23,133 — 23,133 Inventories 26,742 (12,481) 14,261 Property and equipment 4,512 (3,016) 1,496 Intangible assets 160,900 32,500 193,400 Other assets 9,629 (1,964) 7,665 Total identifiable assets acquired $ 232,501 $ 15,039 $ 247,540 Accounts payable 21,574 — 21,574 Accrued rebates, returns and discounts 33,254 — 33,254 Other accrued liabilities 15,434 8,424 23,858 Contingent consideration (a) 29,400 10,500 39,900 Debt (b) 111,900 (600) 111,300 Total liabilities assumed $ 211,562 $ 18,324 $ 229,886 Net identifiable assets acquired 20,939 (3,285) 17,654 Goodwill (c) 14,147 3,285 17,432 Net assets acquired 35,086 — $ 35,086 (a) Contingent consideration was recognized and measured at an estimated fair value as of the acquisition date. The contingent consideration liability assumed is the result of Zyla’s previous acquisition of INDOCIN Products. The liability assumed included contingent consideration related to royalties payable in the form of an earnout provision based on INDOCIN Product revenue estimates and a probability assessment with respect to the likelihood of achieving the level of net sales that would trigger the contingent payment. The fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement as defined in fair value measurement accounting. The key assumptions in determining the fair value are the discount rate and the probability assigned to the potential milestones being achieved. At each reporting date, the Company will subsequently re-measure the contingent consideration obligation to estimated fair value. Any changes in the fair value of contingent consideration will be recognized in operating expenses until the contingent consideration arrangement is settled. (b) The fair value of acquired debt is comprised of the following (in thousands): 13% Senior Secured Note due 2024 $ 95,000 Royalty rights obligation 3,300 Promissory note 3,000 Credit agreement 10,000 Total debt $ 111,300 Upon the Zyla Merger, the Company assumed and immediately paid off a $3.0 million promissory note. The promissory note was scheduled to mature on July 31, 2020. Additionally upon the Zyla Merger, the Company assumed and immediately paid off a $10.0 million credit agreement. The credit agreement was recognized by Zyla as a related party transaction as the lenders were also holders of a portion of the Zyla’s 13% Notes that were issued on January 31, 2019. The Credit Agreement was scheduled to mature on March 20, 2022. See Note 9, Debt , for further information regarding assumed Debt. (c) The Company recognized $17.4 million of goodwill which represents the fair value of assets net of the fair value of liabilities assumed in excess of consideration paid. Goodwill arising from the Zyla Merger is not expected to be deductible for tax purposes and is subject to material revision as the purchase price allocation is completed. The goodwill recognized is attributable primarily to expected synergies and the assembled workforce of Zyla. Stock-based Compensation Plan On June 4, 2020, the Company filed a Registration Statement with the SEC to register the Zyla Life Sciences Amended and Restated 2019 Stock-Based Incentive Compensation Plan (the 2019 Zyla Plan). The 2019 Zyla Plan was assumed in connection with the Zyla Merger. Pursuant to the Zyla Merger Agreement, each outstanding Zyla stock option was cancelled and converted into a stock option to purchase the Company’s Common Stock on the same terms and conditions with (1) the number of shares of Company Common Stock subject to each such option equal to (i) the number of shares of the common stock subject to the option multiplied by (ii) the Merger Exchange Ratio, which was 2.5, rounded, if necessary, to the nearest whole share and (2) an exercise price per share (rounded to the nearest whole cent) equal to the original exercise price of the Zyla stock option divided by (B) the Exchange Ratio. This resulted in the issuance of 5.0 million options with an average fair market value of $0.62 per share value, of which $0.4 million was recognized as merger consideration. The term of Zyla options may not exceed 10 years from the date of grant. An option shall be exercisable on or after each vesting date in accordance with the terms set forth in the option agreement. The right to exercise an option generally vests over three years at the rate of at least 33%, by the end of the first year and then ratably in monthly installments over the remaining vesting period of the stock option. Warrant Agreements Upon the Zyla Merger, the Company assumed Zyla’s warrant agreements (the “Warrant Agreements”) with Iroko Pharmaceuticals, Inc. (“Iroko”) certain of Iroko’s affiliates and certain other parties entitled to receive shares of the Company’s common stock as consideration pursuant to Zyla’s prior agreements or in satisfaction of certain claims pursuant to the Zyla’s prior reorganization plan. The warrants are exercisable at any time at an exercise price of $0.0004 per share, subject to certain ownership limitations including, with respect to Iroko and its affiliates, that no such exercise may increase the aggregate ownership of the Company’s outstanding common stock of such parties above 49% of the number of shares of its common stock then outstanding for a period of 18 months. All of the Company’s outstanding warrants have similar terms whereas under no circumstance may the warrants be net-cash settled. As such, all warrants are equity-classified . Pro Forma Information Supplemental unaudited proforma information is based upon accounting estimates and judgments that the Company believes are reasonable. This supplemental unaudited pro forma financial information has been prepared for comparative purposes only, and is not necessarily indicative of what actual results would have occurred, or of results that may occur in the future. The following table reflects the pro forma consolidated total revenues and net loss for the periods presented, as if the acquisition of Zyla had occurred on January 1, 2019. Unaudited Twelve Months Ended December 31, 2020 2019 Total revenues $ 131,969 $ 246,375 Net loss $ (60,105) $ (145,418) The unaudited proforma financial results for the years ended December 31, 2020 and December 31, 2019 reflect adjustments directly attributed to the business combination and the Company’s divestiture of NUCYNTA and Gralise. Additionally, the unaudited proforma information for the twelve months ended December 31, 2019 was adjusted and excludes income of $115.2 million related to Zyla’s pre-merger reorganization in January 2019 and Assertio’s December 2019 loss on impairment of intangible assets of $189.8 million. See Note 3, Revenue , for revenue for the period since the acquisition date to December 31, 2020 related to Zyla acquired products. As the Company operates as one operating entity, earnings of Zyla since the acquisition date are impractical to calculate separate from the consolidated company.

REVENUE

REVENUE	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE The following table reflects summary revenues the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Product sales, net: INDOCIN Products (1) $ 31,684 $ — CAMBIA 28,350 32,453 Zipsor 13,286 12,498 SPRIX ( (1) 11,077 — Other (2) 9,101 63,855 Total product sales, net 93,498 108,806 Commercialization agreement revenue, net 11,258 118,614 Royalties and milestone revenue 1,519 2,084 Total revenues $ 106,275 $ 229,504 (1) Products acquired in connection with Zyla Merger represent product sales, net for the period of May 20, 2020 through December 31, 2020. (2) Includes product sales for Gralise, which was divested in January 2020; product sales adjustments for previously divested products NUCYNTA and Lazanda; and, product sales for non-promoted products OXAYDO and SOLUMATRIX, which were acquired from Zyla in May 2020. Product Sales, net For the year ended December 31, 2020, product sales primarily consisted of sales from INDOCIN Products, CAMBIA, Zipsor and SPRIX. The Company began shipping and recognizing product sales for INDOCIN Products, SPRIX, and non-promoted products, SOLUMATRIX and OXAYDO, upon the Zyla Merger on May 20, 2020. Product sales for the Company’s non-promoted products, SOLUMATRIX and OXAYDO, acquired upon the Zyla Merger were $7.7 million for the year ended December 31, 2020. In September 2020, we terminated our iCeutica License and as a result will no longer manufacture products using SOLUMATRIX technology. The Company completed the sale of Gralise to Alvogen on January 10, 2020, and therefore ceased recognizing product sales related to Gralise effective on the transaction close date. Product sales related to Gralise for the year ended December 31, 2020 were $0.3 million and relate to sales reserve estimate adjustments related to sales recognized in prior periods. Product sales of Gralise for the year ended December 31, 2019 were $63.1 million. The Company ceased recording product sales and related costs for NUCYNTA after commencing the Commercialization Agreement with Collegium on January 8, 2018. Product sales for the year ended December 31, 2020 and 2019 reflect adjustments made for previously recorded sales reserve estimates. In addition, the Company ceased recording revenues and related costs associated with Lazanda after it divested the product to Slán in November 2017. Product sales for the year ended December 31, 2020 and 2019 reflect adjustments made for previously recorded sales reserve estimates. Commercialization Agreement Revenue, net The Company ceased recognizing commercialization revenue and related costs for NUCYNTA effective the closing of the transaction to divest its rights, title and interest in and to the NUCYNTA franchise to Collegium on February 13, 2020. In connection with the sale, the Commercialization Agreement terminated at closing with certain specified provisions of the Commercialization Agreement surviving in accordance with the terms of the purchase agreement. During the year ended December 31, 2020, the Company recognized net revenue from the Commercialization Agreement of $11.3 million. This included variable royalty revenue of $13.1 million offset by the amortization of the $1.8 million net contract asset in connection with the termination of the Commercialization Agreement as a result of the divestiture of NUCYNTA to Collegium. For the year ended December 31, 2019, the Company recognized net revenue from the Commercialization Agreement of $118.6 million which primarily consists of sales-based variable royalty revenue. Contract Assets The following table reflects changes in the Company’s contract asset as of December 31, 2020 (in thousands): Balance as of Balance as of December 31, 2019 Additions Deductions December 31, 2020 Contract assets: Contract asset - Collegium, net 1,896 — (1,896) — $ 1,896 $ — $ (1,896) $ — The Collegium contract asset, net represented the conditional right to consideration for completed performance under the Commercialization Agreement arising from the transfer of inventory to Collegium on the date of closing of the agreement in January 2018 net of the contract liability of $10.0 million resulting from the upfront payment received and the $8.8 million of warrants received in connection with the Commercialization Amendment. In connection with the divestiture of NUCYNTA to Collegium the Company amortized the remaining balance of the contract asset during the year ended December 31, 2020. Royalties and Milestone Revenue In November 2010, the Company entered into a license agreement with Tribute Pharmaceuticals Canada Ltd. (now known as Nuvo Pharmaceuticals, Inc.) granting them the rights to commercially market CAMBIA in Canada. Nuvo independently contracts with manufacturers to produce a specific CAMBIA formulation in Canada. The Company receives royalties on net sales on a quarterly basis as well as certain one-time contingent milestone payments upon the occurrence of certain events. The Company recognized revenue related to CAMBIA in Canada of $1.5 million and $2.1 million, respectively, for the years ended December 31, 2020, and 2019.

ACCOUNTS RECEIVABLES, NET

ACCOUNTS RECEIVABLES, NET	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
ACCOUNTS RECEIVABLES, NET	ACCOUNTS RECEIVABLES, NET The following table reflects accounts receivables, net, as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Receivables related to product sales, net $ 40,784 $ 38,353 Receivables from Collegium 3,566 4,104 Other — 287 Total Accounts receivable, net $ 44,350 $ 42,744

INVENTORIES, NET

INVENTORIES, NET	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
INVENTORIES, NET	INVENTORIES, NET The following table reflects the components of inventory, net as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Raw materials $ 1,136 $ 1,065 Work-in-process 1,340 426 Finished goods 9,236 1,921 Total Inventories, net $ 11,712 $ 3,412 As of December 31, 2020 and 2019 inventory reserves were $2.3 million and $0.4 million, respectively. The increase in inventory reserve was primarily attributable to the Zyla Merger.

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT, NET	PROPERTY AND EQUIPMENT, NET The following table reflects property and equipment as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Furniture and office equipment $ 2,680 $ 2,557 Machinery and equipment — 2,731 Laboratory equipment 20 221 Leasehold improvements 10,523 9,858 13,223 15,367 Less: Accumulated depreciation and amortization (10,786) (11,870) Property and equipment, net $ 2,437 $ 3,497 Depreciation expense was $1.6 million, and $1.2 million for the years ended December 31, 2020 and 2019, respectively. During the year ended December 31, 2020, the Company retired machinery and equipment assets related to divested Gralise and NUNCYTA products as those assets would no longer be in use and were fully depreciated. In connection with the Company’s December 2020 restructuring plan, certain property and equipment, including leasehold improvements at the Wayne, Pennsylvania office, were determined to be no longer be in use and abandoned, and therefore the Company recognized a loss on disposition of $0.9 million which is included in Restructuring charges within the Company’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2020.

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND GOODWILL	INTANGIBLE ASSETS AND GOODWILL Intangible Assets The following table reflects the gross carrying amounts and net book values of intangible assets as of December 31, 2020 and 2019 (in thousands): December 31, 2020 December 31, 2019 Product rights Remaining Gross Accumulated Net Book Gross Accumulated Impairment Net Book INDOCIN Products 11.4 $ 154,100 $ (7,812) $ 146,288 $ — $ — $ — $ — SPRIX 6.4 39,000 (3,389) 35,611 — — — — CAMBIA 3.0 51,360 (36,163) 15,197 51,360 (31,027) — 20,333 Zipsor 1.2 27,250 (24,381) 2,869 27,250 (22,044) 5,206 OXAYDO 0.4 300 (183) 117 — — — — NUCYNTA 0.0 — — — 1,019,978 (455,192) (189,790) 374,996 Total Intangible Assets $ 272,010 $ (71,928) $ 200,082 $ 1,098,588 $ (508,263) $ (189,790) $ 400,535 Amortization expense was $24.8 million and $101.8 million for the years ended December 31, 2020 and 2019, respectively. In connection with the Zyla Merger during the year ended December 31, 2020, the Company acquired identified intangible assets comprised of definite-lived product rights for INDOCIN Products, SPRIX, and OXAYDO which are amortized on a straight-line basis over their respective estimated useful lives. The respective fair values were determined to be $154.1 million, $39.0 million, and $0.3 million, as of the Zyla Merger date of May 20, 2020. As of December 31, 2020, the Company determined there were indicators of impairment present related to the declining revenues due to the adverse impact of COVID-19 on its business as well as unfavorable changes in product payor mix, resulting in the Company’s announcement of the December 2020 Plan. These factors contributed to higher operating losses and cash used by operating activities during the year ended December 31, 2020, as compared to the prior year. In addition, during the fourth quarter of 2020, the Company’s market capitalization declined from approximately $72.0 million as of September 30, 2020 to $38.0 million as of December 31, 2020. As a result of these recent events, the Company determined indicators of impairment were present and, accordingly, performed a test for recoverability of long-lived assets to be held and used pursuant to ASC 360, Impairment Testing: Long Lived Assets Classified as Held and Used. After grouping the long-lived assets, including purchased developed technology and trademarks, at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other assets and liabilities, the Company estimated the future net undiscounted cash flows expected to be generated from the use of the long-lived asset group and its eventual disposition. The Company then compared the estimated undiscounted cash flows to the carrying amount of the long-lived asset group. Based on this test, the Company determined that the estimated undiscounted cash flows were in excess of the carrying amount of the long-lived asset group and, accordingly, the long-lived asset group is fully recoverable. As of December 31, 2019, the Company determined there were indicators of impairment present related to the NUCYNTA intangible asset based on current unfavorable commercial outlook resulting in a downward revision to the expected future cash flows from the NUCYNTA franchise, which made the carrying amount not recoverable. As a result, the Company recognized an impairment loss of $189.8 million on the NUCYNTA intangible asset to reduce the carrying value of $564.8 million to its estimated fair value of $375.0 million as of December 31, 2019. The evaluation of fair value was determined under ASC 820, Fair Value Measurement (ASC 820) as the price that would be received to sell the asset in an orderly transaction between market participants at the measurement date of December 31, 2019. The fair value was based on a combination of an income approach and the observable transaction price from Collegium’s purchase of the NUCYNTA franchise in February 2020. The income approach consisted of the present value of future cash flows that a market participant would expect to receive from holding the asset in its current use. This included assumptions of a market participant’s view such as, but not limited to, future product net sales, related operating expenses, competitive landscape, and a discount rate to reflect the risk inherent in the future cash flows. The following table reflects expected future amortization expense related to the Company’s intangible assets (in thousands): Year Ending December 31, Estimated 2021 $ 26,004 2022 24,081 2023 23,337 2024 18,413 Thereafter 108,247 Total $ 200,082

ACCRUED LIABILITIES

ACCRUED LIABILITIES	12 Months Ended
	Dec. 31, 2020
Accounts Payable and Accrued Liabilities, Current [Abstract]
ACCRUED LIABILITIES	ACCRUED LIABILITIES The following table reflects accrued liabilities as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Accrued compensation $ 5,498 $ 6,188 Accrued consent fees 4,500 — Accrued restructuring and one-time termination costs 8,744 3,763 Other accrued liabilities 12,829 8,997 Total accrued liabilities $ 31,571 $ 18,948

DEBT

DEBT	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
DEBT	DEBT The following table reflects the Company’s debt as of December 31, 2020 and 2019 (in thousands): December 31, 2020 December 31, 2019 13% Senior Secured Note due 2024 (1) $ 80,250 $ — Royalty rights obligation (2) 3,533 — 2.50% Convertible Notes due 2021 335 145,000 5.00% Convertible Notes due 2024 (3) — 120,000 Senior Secured Notes (4) — 162,500 Total principal amount 84,118 427,500 Unamortized debt discounts (16) (70,699) Unamortized debt issuance costs — (5,543) Carrying value 84,102 351,258 Less: current portion of long-term debt (11,942) (80,000) Net, long-term debt $ 72,160 $ 271,258 (1) In connection with the Zyla Merger on May 20, 2020, the Company assumed the obligations of Zyla under its Existing Indenture, and Assertio and the other subsidiaries of the Company (other than Depo DR) became guarantors of Zyla's 13% Senior Secured Notes due 2024. (2) In connection with the Zyla Merger on May 20, 2020, the Company assumed the obligations of Zyla under its royalty rights agreement with each holder of its 13% Senior Secured Notes due 2024. (3) 2024 Notes settled and retired as of June 30, 2020. (4) During the year ended December 31, 2020, the Company repaid in full the outstanding aggregate principal amount of its Senior Secured Notes. 13% Senior Secured Notes due 2024 In accordance with the Zyla Merger, Assertio assumed $95.0 million aggregate principal amount of 13% senior secured notes due 2024 (the Secured Notes) issued pursuant to an indenture (the Existing Indenture) entered into on January 31, 2019, by and among Zyla Life Sciences, the guarantors party thereto (the Guarantors) and Wilmington Savings Fund Society, FSB (as successor to U.S. Bank National Association), as trustee and collateral agent (the Trustee). The Secured Notes were issued in two series: $50.0 million of Series A-1 Notes and $45.0 million of Series A-2 Notes. The Secured Notes are reported within current portion of long-term debt and long-term debt on the Consolidated Balance Sheets. The fair value of assumed debt has been measured based on estimates using assumptions that management believes are reasonable and based on information that is currently available. As of May 20, 2020, the Existing Indenture was modified by a Supplemental Indenture (the Supplem ental Indenture and the Existing Indenture, as so modified, the Indenture), pursuant to which Assertio (the Issuer) assumed the obligations as issuer of the Secured Notes and the subsidiaries of Assertio became guarantors of the Secured Notes. The Supplemental Indenture, among other things, provides for certain amendments to the restrictive covenants in the Indenture. Interest on the Secured Notes accrues at a rate of 13% per annum and is payable semi-annually in arrears on May 1 and November 1 of each year (each, a Payment Date). The Existing Indenture also requires amortization payments of outstanding principal on the Secured Notes equal to 10% per annum, payable semi-annually on each Payment Date. The Secured Notes are senior secured obligations of the Issuer and are secured by a lien on substantially all assets of the Issuer and the guarantors. The stated maturity date of the Secured Notes is January 31, 2024. Upon the occurrence of a Change of Control, subject to certain conditions (as defined in the Existing Indenture), holders of the Secured Notes may require the Issuer to repurchase for cash all or part of their Secured Notes at a repurchase price equal to 100% of the principal amount of the Secured Notes to be repurchased, plus accrued and unpaid interest to the date of repurchase. The Issuer may redeem the Secured Notes at its option, in whole or in part from time to time, at a redemption price equal to 100% of the principal amount of the Secured Notes being redeemed, plus accrued and unpaid interest, if any, through the redemption date. No sinking fund is provided for the Secured Notes. Pursuant to the Supplemental Indenture, Assertio and its restricted subsidiaries must also comply with certain covenants, including limitations on the issuance of debt; the issuance of preferred and/or disqualified stock; the payment of dividends and other restricted payments; the prepayment, redemption or repurchase of subordinated debt; mergers, amalgamations or consolidations; engaging in certain transactions with affiliates; and the making of investments. In addition, the Issuer must maintain a minimum level of consolidated liquidity, based on unrestricted cash on hand and availability under any revolving credit facility, equal to the greater of (1) the quotient of the outstanding principal amount of the Secured Notes divided by 9.5 and (2) $7.5 million. The Company was in compliance with its covenants with respect to the Secured Notes as of December 31, 2020. On July 31, 2020, the Company voluntarily redeemed $10.0 million of aggregate principal plus accrued interest on its Secured Notes due 2024. The following is a summary of Secured Notes interest expense for the year ended December 31, 2020 (in thousands): December 31, 2020 Stated coupon interest $ 6,870 Total interest expense $ 6,870 The Secured Notes do not have associated debt discount or debt issuance costs. Royalty Rights Obligation In accordance with the Zyla Merger, the Company assumed a royalty rights agreement (the Royalty Rights) with each of the holders of its Secured Notes pursuant to which the Company will pay the holders of the Secured Notes an aggregate 1.5% royalty on Net Sales (as defined in the Existing Indenture) through December 31, 2022. The Royalty Rights were determined to be a freestanding element with respect to the Secured Notes and the Company is accounting for the Royalty Rights obligation relating to future royalties as a debt instrument. The Company has Royalty Rights obligations of $3.5 million as of December 31, 2020, with $2.1 million cla ssified as current and $1.4 million classified as non-current debt in the Company’s Consolidated Balance Sheets. The Company recognized $0.2 million of interest expense related the Royalty Rights during the year ended December 31, 2020. The accounting for the Royalty Rights requires the Company to make certain estimates and assumptions about the future net sales. The estimates of the magnitude and timing of net sales are subject to significant variability due to the extended time period associated with the financing transaction and are thus subject to significant uncertainty. 2.50% Convertible Senior Notes Due 2021 On September 9, 2014, the Company issued $345.0 million aggregate principal amount of 2.50% Convertible Senior Notes Due 2021 (the 2021 Notes) resulting in net proceeds to the Company of $334.2 million after deducting the underwriting discount and offering expenses of $10.4 million and $0.4 million, respectively. The 2021 Notes were issued pursuant to an indenture, as supplemented by a supplemental indenture dated September 9, 2014, between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee (the Trustee), and mature on September 1, 2021, unless earlier converted, redeemed, or repurchased. The 2021 Notes bear interest at the rate of 2.50% per annum, payable semi-annually in arrears on March 1 and September 1 of each year, beginning March 1, 2015. Prior to March 1, 2021, holders of the 2021 Notes can convert their securities, at their option: (i) during any calendar quarter commencing after December 31, 2015, if the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to $25.01 (130.0% of the $19.24 (conversion price) on each applicable trading day (ii) during the 5 business day period after any 5 consecutive trading day period in which the trading price per 1,000 principal amount of notes for each trading day of the measurement period was less than 98.0% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; and (iii) at any time upon the occurrence of specified corporate transactions, to include a change of control (as defined in the Notes Indenture). On or after March 1, 2021 to the close of business on the second scheduled trading day immediately preceding the maturity date, the holders of the 2021 Convertible Notes may convert all or any portion of their notes, in multiples of 1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. The initial conversion rate of 51.9852 shares of common stock per 1,000 principal amount of Convertible Notes is equivalent to a conversion price of approximately $19.24 per share of common stock. Upon conversion, the Company will pay or deliver, as appropriate, 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 election. If the conversion obligation is satisfied solely in cash or through payment and delivery of a combination of cash and shares, the amount of cash and shares, if any, due upon conversion will be based on a daily conversion value calculated on a proportionate basis for each trading day in a 40 trading day observation period. The 2021 Notes bear interest at the rate of 2.50% per annum, payable semi-annually in arrears on March 1 and September 1 of each year, beginning March 1, 2015. The 2021 Notes were accounted for in accordance with ASC Subtopic 470-20, Debt with Conversion and Other Options (ASU Subtopic 470-20) . Pursuant to ASC Subtopic 470-20, since the 2021 Notes can be settled in cash, shares of common stock or a combination of cash and shares of common stock at the Company’s option, the Company is required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of any outstanding debt instrument is computed by estimating the fair value of a similar liability without the conversion option. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the convertible debt instrument. The effective interest rate used in determining the liability component of the 2021 Notes was 9.34%. This resulted in the initial recognition of $226.0 million as the liability component net of a $119.0 million debt discount with a corresponding net of tax increase to paid-in capital of $73.3 million representing the equity component of the 2021 Notes. The underwriting discount of $10.4 million and offering expenses of $0.4 million were allocated between debt issuance costs and equity issuance costs in proportion to the allocation of the proceeds. Equity issuance costs of $3.7 million related to the convertible notes were recorded as an offset to additional paid-in capital. On August 13, 2019, the Company entered into separate, privately negotiated exchange agreements (the Exchange Agreements) with a limited number of holders of the 2021 Notes. The Company exchanged (the Convertible Note Exchange) $200.0 million aggregate principal amount of the 2021 Notes for a combination of (a) its new $120.0 million aggregate principal amount of 5.0% Convertible Senior Notes due August 15, 2024 (the 2024 Notes), (b) an aggregate cash payment of $30.0 million, and (c) an aggregate of 15.8 million shares of the Company’s common stock. The Company did not receive any cash proceeds from the issuance of the 2024 Notes or the issuance of the shares of its common stock. In connection with the Convertible Note Exchange a beneficial owner holding more than 10% of the Company’s common stock exchanged $22.0 million in aggregate principal of the 2021 Notes for a combination of $13.2 million in aggregate principal of the 2024 Notes, 1.7 million shares of the Company’s common stock, and $3.5 million in cash. The Convertible Note Exchange was accounted for in accordance with ASC 470-50, Debt Modifications and Extinguishments (ASC 470-50). Pursuant to ASC 470-50, the Convertible Note Exchange was deemed to be an extinguishment of debt as there was a substantive modification in the conversion option of the 2024 Notes from 2021 Notes. During the year ended December 31, 2019, the Company recognized a $26.4 million gain on debt extinguishment, which represented the difference between the carrying value and the fair value of the 2021 Notes just prior to Convertible Note Exchange. The Company also recognized reacquisition of $6.2 million in additional paid-in capital related to the equity component of the 2021 Notes based on the excess of the fair value of total considerations provided in the Convertible Note Exchange against the fair value of the 2021 Notes just prior to the Convertible Note Exchange. The components of total consideration given in the Convertible Note Exchange consisted of (a) the new 2024 Notes, (b) an aggregate cash payment of $30.0 million, and (c) an aggregate of 15.8 million shares of the Company’s common stock. Upon completion of the Convertible Note Exchange, the aggregate principal amount of the 2021 Notes was reduced by $200.0 million to $145.0 million, the unamortized debt discount and debt issuance costs was reduced by $26.1 million to $18.9 million and the carrying amount of the equity component was reduced by $6.2 million to $112.8 million. During February 2020, the Company entered into separate, privately negotiated purchase agreements (Purchase Agreements) with a limited number of holders of the Company’s currently outstanding 2021 Notes and 2024 Notes. The Company used proceeds from the sale of Gralise and NUCYNTA to repurchase $102.5 million aggregate principal amount of 2021 Notes for a cash payment plus accrued but unpaid interest. The repurchase of the 2021 Notes was accounted for in accordance with ASC 470-50, and accordingly, during the year ended December 31, 2020, the Company recognized a $10.3 million loss on debt extinguishment, which represented the difference between the carrying value and the fair value of the 2021 Notes just prior to the repurchase plus transaction costs. The Company also recognized reacquisition of $0.3 million in additional paid-in capital related to the equity component of the 2021 Notes based on the excess of the fair value of total considerations provided against the fair value of the 2021 Notes just prior to the repurchase. Additionally, during April 2020, the Company completed its public tender offers to purchase the 2021 Notes for cash in an amount equal to $995.00 per $1,000 principal amount (exclusive of accrued and unpaid interest) from each registered holder of the 2021 Notes. As a result of the tender offer, a total of $42.1 million in aggregate principal amount of the 2021 Notes were properly tendered and purchased by the Company. The tender offer of the 2021 Notes was accounted for in accordance with ASC 470-50, and the Company recognized a $3.9 million loss on debt extinguishment during the year ended December 31, 2020, which represented the difference between the carrying value and the fair value of the 2021 Notes just prior to the tender offer plus transaction costs. As a result of the February 2020 repurchase and the April 2020 tender offer transactions, the aggregate principal amount of the 2021 Notes was reduced to $0.3 million and the unamortized debt discount and debt issuance costs eliminated as of December 31, 2020. Based on the Company’s intention to settle in cash the total remaining outstanding aggregate principal of 2021 Notes, the liability component of the 2021 Notes is classified as part of current portion of long-term debt on the Company’s Consolidated Balance Sheet as of December 31, 2020. The closing price of the Company’s common stock did not exceed 130% of the $19.24 conversion price, for the required period during the quarter ended December 31, 2020. As a result, the 2021 Notes are not convertible as of December 31, 2020. The following is a summary of the liability component of the 2021 Notes as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Principal amount of the 2021 Notes $ 335 $ 145,000 Unamortized discount of the liability component — (14,963) Unamortized debt issuance costs — (725) Total 2021 Notes $ 335 $ 129,312 The debt discount and debt issuance costs are amortized as interest expense using the effective interest method. The following is a summary of interest expense for the 2021 Notes for the years ended December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Stated coupon interest $ 637 $ 6,708 Amortization of debt discount and debt issuance costs 1,550 15,398 Total interest expense 2021 Notes $ 2,187 $ 22,106 5.00% Convertible Senior Notes Due 2024 On August 13, 2019, as part of the Convertible Note Exchange, the Company issued $120.0 million aggregate principal of Convertible Senior Notes Due 2024 (the 2024 Notes) which mature on August 14, 2024 and bear interest at a rate of 5.0%, payable semiannually in arrears on February 15 and August 15 of each year, beginning on February 15, 2020. The 2024 Notes were issued pursuant to the Third Supplemental Indenture (the Third Indenture), dated August 13, 2019, to the indenture of the 2021 Notes, dated September 9, 2014, between the Company and the Bank of New York Mellon Trust Company, N.A. Holders may convert their 2024 Notes at any time prior to the earlier of (i) the close of business on the trading day immediately preceding the Maturity Date and (ii) if the Company calls the 2024 Notes for optional redemption, the close of business on the second trading day prior to the redemption date. The 2024 Notes will be convertible at an initial conversion rate of 323.5198 shares per $1,000 in principal amount, equivalent to a conversion price of approximately $3.09 per share. The Company may settle conversions in 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 election. If the conversion obligation is satisfied solely in cash or through payment and delivery of a combination of cash and shares of the Company’s common stock, the amount of cash and shares of common stock, if any, due upon conversion will be based on a daily conversion value calculated on a proportionate basis for each trading day in a 40 consecutive trading day observation period. Upon the occurrence of a fundamental change (as defined in the Third Indenture) at any time, the holder of the 2024 Notes will have the right to require the Company to repurchase for cash any or all the 2024 Notes, or any portion of the principal amount, that is equal to $1,000 or a multiple of $1,000. The price the Company is required to pay equals 100% of the principal amount plus accrued and unpaid interest (up to but excluding the fundamental change purchase date). On or after August 20, 2020, the Company may redeem for cash all or part of the notes, at its option, if the last reported sale price of the Company’s common stock has been at least 150% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption. The redemption price is equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. Upon conversion as a result of an optional redemption by the Company, the holder will also receive a payment equal to all remaining required interest payments due on each $1,000 principal amount being converted through and including the maturity date (excluding accrued but unpaid interest to the applicable conversion date), known as an interest make-whole payment. The Company may pay any interest make-whole amount either in cash, in shares of common stock or a combination thereof, at its election. Upon the occurrence of an event of default (as defined by the Third Indenture), the holders of the notes may accelerate the maturity of the notes and 100% of the principal and accrued and unpaid interest shall be due and payable immediately. If the Company fails to comply with certain reporting covenants under the Supplemental Indenture, the Company may elect to pay additional interest on the 2024 Notes as the sole remedy for such default. Additionally, if the Company consolidates or merges with or into, sells, conveys, transfers or leases its consolidated properties and assets substantially as an entirety to a foreign entity, it may be required to pay additional amounts for withholding taxes, duties, assessments or governmental charges as necessary to the 2024 Note holders. The 2024 Notes are accounted for in accordance with ASC Subtopic 470-20. The effective interest rate used in determining the liability component of the 2024 Notes was 17.82%. The fair value of the 2024 Notes, which also represents the proceeds received, was $98.4 million as of the date of the Convertible Note Exchange. This resulted in the recognition of $65.8 million as the liability component of the 2024 Notes and the recognition of the residual $54.2 million as the debt discount composed of $21.6 million in fair value discount and $32.6 million for the equity component. The equity component is reflected as an increase to additional paid-in capital. The total issuance costs of $4.3 million were allocated between the debt and equity issuance costs in proportion to the allocation of the liability and equity components of the 2024 Notes. Total debt issuance costs of $2.9 million were recorded on the issuance date and are reflected in the Company’s Consolidated Balance Sheet as a direct deduction from the carrying value of the associated debt liability. The debt discount and debt issuance costs will be amortized as interest expense through maturity using the effective interest method. During the year ended December 31, 2020, the Company entered into Purchase Agreements with a limited number of holders of the Company’s outstanding 2021 Notes and 2024 Notes. The Company used proceeds from the sale of Gralise and NUCYNTA to repurchase $85.5 million aggregate principal amount of 2024 Notes for a cash payment plus accrued but unpaid interest. The repurchase of the 2024 Notes was accounted for in accordance with ASC 470-50. During the year ended December 31, 2020, the Company recognized a $21.3 million loss on debt extinguishment, which represented the difference between the carrying value and the fair value of the 2024 Notes just prior to the repurchase plus transaction costs. The Company also recognized reacquisition of $16.8 million in additional paid-in capital related to the equity component of the 2024 Notes based on the excess of the fair value of total considerations provided against the fair value of the 2024 Notes just prior to the repurchase. Additionally, during the year ended December 31, 2020, the Company completed its public tender offers to purchase the 2024 Notes for cash in an amount equal to $995.00 per $1,000 principal amount (exclusive of accrued and unpaid interest) from each registered holder of the 2024 Notes. As a result of the tender offer, a total of $34.5 million in aggregate principal amount of the 2024 Notes were properly tendered and purchased by the Company. The tender offer of the 2024 Notes was accounted for in accordance with ASC 470-50. During the year ended December 31, 2020, the Company recognized a $12.4 million loss on debt extinguishment, which represented the difference between the carrying value and the fair value of the 2024 Notes just prior to the tender offer plus transaction costs. The Company also recognized reacquisition of $2.7 million in additional paid-in capital related to the equity component of the 2024 Notes based on the excess of the fair value of total considerations provided against the fair value of the 2024 Notes just prior to the repurchase. As a result of the 2020 repurchase and tender offer transactions, the 2024 Notes were settled and retired in full with no amount and the unamortized debt discount and debt issuance costs remaining as of December 31, 2020. The following is a summary of the liability component of the 2024 Notes as of December 31, 2019 (in thousands): December 31, 2019 Principal amount of the 2024 Notes $ 120,000 Unamortized discount of the liability component (51,701) Unamortized debt issuance costs (2,796) Total 2024 Notes $ 65,503 As of December 31, 2020, the Company had repaid in full all outstanding 2024 Notes. The debt discount and debt issuance costs are amortized as interest expense using the effective interest method. The following is a summary of interest expense for the 2024 Notes for the years ended December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Stated coupon interest $ 1,090 $ 2,250 Amortization of debt discount and debt issuance costs 1,273 2,583 Total interest expense 2024 Notes $ 2,363 $ 4,833 Senior Secured Notes On April 2, 2015, the Company issued $575.0 million aggregate principal amount of senior secured notes (the Senior Notes) for aggregate gross proceeds of approximately $562.0 million pursuant to a Note Purchase Agreement dated March 12, 2015 (Note Purchase Agreement) among the Company and Deerfield Private Design Fund III, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Special Situations Fund, L.P., Deerfield Private Design Fund II, L.P., Deerfield Private Design International II, L.P., BioPharma Secured Investments III Holdings Cayman LP, Inteligo Bank Ltd. and Phemus Corporation (collectively, the Purchasers) and Deerfield Private Design Fund III, L.P., as collateral agent. The Company used $550.0 million of the net proceeds received upon the sale of the Senior Notes to fund a portion of the Purchase Price paid to Janssen Pharma in connection with the NUCYNTA acquisition. As of February 13, 2020, the Company had repaid in full all outstanding indebtedness, and terminated all commitments and obligations, under its Note Purchase Agreement. The Company used proceeds from the sale of Gralise and NUCYNTA to repay the outstanding principal of $162.5 million. In addition, the Company paid approximately $4.9 million and $4.4 million in prepayment premiums and accrued exit fees, respectively, plus accrued but unpaid interest. In connection with the termination of the Note Purchase Agreement, the Company was released from all security interests, liens and encumbrances under the Note Purchase Agreement. Accordingly, during the year ended December 31, 2020, the Company recognized a loss on debt extinguishment of $8.2 million composed of the $4.9 million prepayment fee and $3.3 million of unamortized debt discount and debt issuance costs, recognized as part of loss on debt extinguishment in the Company’s Consolidated Statement of Comprehensive Income. The Senior Notes were secured by substantially all of the assets of the Company and any subsidiary guarantors, and the interest rate was equal to the lesser of (i) 9.75% over the three-month London Inter-Bank Offer Rate (LIBOR), subject to a floor of 1.00%and (ii) 11.95% (through the third anniversary of the purchase date) and 12.95% (thereafter). The interest rate is determined at the first business day of each fiscal quarter, commencing with the first such date following April 2, 2015. The following is a summary of the carrying value of the Senior Notes as of December 31, 2019 (in thousands): 2019 Principal amount of the Senior Notes $ 162,500 Unamortized debt discount balance (4,035) Unamortized debt issuance costs (2,022) Total Senior Notes $ 156,443 As of December 31, 2020, the Company had repaid in full all outstanding Senior Notes. The debt discount and debt issuance costs are amortized as interest expense using the effective interest method. The following is a summary of Senior Notes interest expense for the years ended December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Contractual interest expense $ 1,648 $ 25,559 Amortization of debt discount and debt issuance costs 2,699 5,783 Total interest expense $ 4,347 $ 31,342

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES The Company continually evaluates its operations to identify opportunities to streamline operations and optimize operating efficiencies as an anticipation to changes in the business environment. On December 15, 2020, the Company announced the December 2020 Plan which is designed to substantially reduce the Company’s operating footprint through the reduction of its workforce. The Company believes the December 2020 Plan will allow it to adapt to the current market environment by reducing cost and better positioning the Company to continue to provide our differentiated products to patients and maximize shareholder value. The reorganization plan included a reduction of staff at our headquarters office and remote sales force. As a result, $9.6 million of severance and benefits costs and $1.6 million of other exit costs, including the write off of fixed assets no longer in use and the early termination of fleet leases, were recognized as restructuring charges, related to the December 2020 Plan, during the year ended December 31, 2020. The Company expects to substantially complete the workforce reduction by the end of the first quarter of 2021. Subsequent to the Zyla Merger in May 2020, the Company began implementing reorganization plans of its workforce and other restructuring activities to realize the synergies of the Zyla Merger and to re-align resources to strategic areas and drive growth. The reorganization plan primarily focused on reduction of staff at the Company’s headquarters offices (Zyla Merger Reorganization). As a result, $5.6 million of severance and benefits costs, which includes $1.0 million of stock-based compensation expense associated with equity modifications for certain executives, and $0.2 million of other exit costs were recognized as restructuring charges, related to the Zyla Merger, during the year ended December 31, 2020. The Company does not expect to incur significant costs related to the Zyla Merger Reorganization beyond 2020. In April 2020, the Company executed a limited reduction to its sales force due to the impact of COVID-19 on its ability to see in-person providers who prescribe our products. As a result, $0.3 million of severance and benefits costs and $0.3 million of other costs were recognized as restructuring charges during the year ended December 31, 2020. This initiative was completed during 2020. In November 2019, the Company announced an acceleration of cost-saving initiatives that included a decision to discontinue its relationship with its contract sales organization, a reduction in the use of certain outside vendors and consultants, and the reorganization of certain functions resulting in a reduction of staff at its headquarters office and remote positions during the fourth quarter of 2019 (the 2019 Plan). As a result, $0.2 million and $3.9 million of severance and benefits costs for the reduction of staff were recognized as restructuring charges, related to the 2019 Plan, during the years ended December 31, 2020 and 2019, respectively. The 2019 cost-saving initiative was substantially complete as of December 31, 2020. The following table reflects total expenses related to restructuring activities recognized within the Consolidated Statement of Comprehensive Income as restructuring charges for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Employee compensation costs $ 15,705 $ 3,891 Other exit costs 2,101 — Total restructuring charges $ 17,806 $ 3,891 The following table reflects cash activity related to the Company’s accrued restructuring as of December 31, 2020 and 2019 (in thousands): Employee separation costs Other exit costs Total Balance as of December 31, 2018 $ 1,578 $ — $ 1,578 Accruals 3,891 $ — 3,891 Cash paid (1,706) — (1,706) Balance as of December 31, 2019 $ 3,763 $ — $ 3,763 Accruals 15,705 2,101 17,806 Adjustment to previous accrual estimate (594) — (594) Write off of fixed assets and leases and other adjustments — (1,888) (1,888) Cash paid (10,130) (213) (10,343) Balance as of December 31, 2020 $ 8,744 $ — $ 8,744

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES As of December 31, 2020, the Company has non-cancelable operating leases for its offices and certain office equipment. The Company has the right to renew the term of the Lake Forest lease for one period of five years, provided that written notice is made to the Landlord no later than twelve months prior to the expiration of the initial term of the lease which is on December 31, 2023. In connection with the Zyla Merger, the company assumed an operating lease for offices in Wayne, Pennsylvania. The Wayne, Pennsylvania office lease terminates in 2022 and will not be renewed. The Company relocated its corporate headquarters from Newark, CA to Lake Forest, Illinois in 2018 and subsequently entered into two subleases which, together, account for the entirety of the Newark facility. Each sublease contains abated rent periods resulting in reduced operating lease cash flows through May 2019. Operating lease costs and sublease income related to the Newark facility are accounted for in Other (loss) gain in the Consolidated Statements of Comprehensive Income. In connection with the December 2020 restructuring plan, the Company’s operating leases for its automobiles used by its sales force were terminated early and the Wayne, Pennsylvania office lease assets was determined to be no longer be in use and abandoned. The Company recognized a charge of $0.7 million to write off the Wayne, Pennsylvania office and automobile lease right-of-use assets, which is included in restructuring charges in the Company’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2020. The following table reflects lease expense for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Financial Statement Classification Operating lease cost Selling, general and administrative expenses $ 1,760 $ 718 Operating lease cost Other (loss) gain 1,391 591 Total lease cost $ 3,151 $ 1,309 Sublease Income Other (loss) gain $ 2,236 $ 1,386 The following table reflects supplemental cash flow information related to leases for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Cash paid for amounts included in measurement of liabilities: Operating cash flows from operating leases $ 3,004 $ 2,446 The following table reflects supplemental balance sheet information related to leases as of December 31, 2020 and 2019 (in thousands): Financial Statement Classification December 31, December 31, Assets Operating lease right-of-use assets Other long-term assets $ 2,347 $ 2,776 Liabilities Current operating lease liabilities Other current liabilities $ 2,683 $ 2,094 Noncurrent operating lease liabilities Other long term liabilities 2,815 4,820 Total lease liabilities $ 5,498 $ 6,914 Future undiscounted cash flows to be received from subleases is expected to be approximately $1.5 million on an annual basis for the years ended December 31, 2021 and 2022. The following table reflects other lease information as of December 31, 2020 and 2019: December 31, December 31, Weighted-average remaining lease term (years): Operating leases 2.2 3.2 Weighted-average discount rate: Operating leases 6.3 % 6.0 % The following table reflects future minimum lease payments under the Company’s non-cancelable operating leases as of December 31, 2020 (in thousands): Lease Payments 2021 2,917 2022 2,308 2023 632 Thereafter — Total lease payments $ 5,857 Less: Interest 359 Present value of lease liabilities $ 5,498
LEASES	LEASES As of December 31, 2020, the Company has non-cancelable operating leases for its offices and certain office equipment. The Company has the right to renew the term of the Lake Forest lease for one period of five years, provided that written notice is made to the Landlord no later than twelve months prior to the expiration of the initial term of the lease which is on December 31, 2023. In connection with the Zyla Merger, the company assumed an operating lease for offices in Wayne, Pennsylvania. The Wayne, Pennsylvania office lease terminates in 2022 and will not be renewed. The Company relocated its corporate headquarters from Newark, CA to Lake Forest, Illinois in 2018 and subsequently entered into two subleases which, together, account for the entirety of the Newark facility. Each sublease contains abated rent periods resulting in reduced operating lease cash flows through May 2019. Operating lease costs and sublease income related to the Newark facility are accounted for in Other (loss) gain in the Consolidated Statements of Comprehensive Income. In connection with the December 2020 restructuring plan, the Company’s operating leases for its automobiles used by its sales force were terminated early and the Wayne, Pennsylvania office lease assets was determined to be no longer be in use and abandoned. The Company recognized a charge of $0.7 million to write off the Wayne, Pennsylvania office and automobile lease right-of-use assets, which is included in restructuring charges in the Company’s Consolidated Statements of Comprehensive Income for the year ended December 31, 2020. The following table reflects lease expense for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Financial Statement Classification Operating lease cost Selling, general and administrative expenses $ 1,760 $ 718 Operating lease cost Other (loss) gain 1,391 591 Total lease cost $ 3,151 $ 1,309 Sublease Income Other (loss) gain $ 2,236 $ 1,386 The following table reflects supplemental cash flow information related to leases for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Cash paid for amounts included in measurement of liabilities: Operating cash flows from operating leases $ 3,004 $ 2,446 The following table reflects supplemental balance sheet information related to leases as of December 31, 2020 and 2019 (in thousands): Financial Statement Classification December 31, December 31, Assets Operating lease right-of-use assets Other long-term assets $ 2,347 $ 2,776 Liabilities Current operating lease liabilities Other current liabilities $ 2,683 $ 2,094 Noncurrent operating lease liabilities Other long term liabilities 2,815 4,820 Total lease liabilities $ 5,498 $ 6,914 Future undiscounted cash flows to be received from subleases is expected to be approximately $1.5 million on an annual basis for the years ended December 31, 2021 and 2022. The following table reflects other lease information as of December 31, 2020 and 2019: December 31, December 31, Weighted-average remaining lease term (years): Operating leases 2.2 3.2 Weighted-average discount rate: Operating leases 6.3 % 6.0 % The following table reflects future minimum lease payments under the Company’s non-cancelable operating leases as of December 31, 2020 (in thousands): Lease Payments 2021 2,917 2022 2,308 2023 632 Thereafter — Total lease payments $ 5,857 Less: Interest 359 Present value of lease liabilities $ 5,498

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES There were no non-cancelable purchase orders related to consulting services as of December 31, 2020. Cosette Pharmaceuticals Supply Agreement Pursuant to the Zyla Merger, the Company assumed a Collaborative License, Exclusive Manufacture and Global Supply Agreement with Cosette Pharmaceuticals, Inc. (formerly G&W Laboratories, Inc.) (the “Supply Agreement”) for the manufacture and supply of INDOCIN Suppositories to Zyla for commercial distribution in the United States. The Company is obligated to purchase all of its requirements for INDOCIN Suppositories from Cosette Pharmaceuticals, Inc., and was required to meet minimum purchase requirements for the calendar year 2020. All 2020 minimum requirements were met. The term of the Supply Agreement extends through July 31, 2023, and there are no minimum requirements in any of the other subsequent years. Catalent Pharma Solutions Commercial Supply Agreement Pursuant to the Zyla Merger, the Company assumed a Commercial Supply Agreement (“CSA”) with Catalent Pharma Solutions (“Catalent Pharma”) for the manufacture of certain specified products. Based on the CSA, the Company is obligated to purchase certain minimum amounts of manufacturing and product maintenance services on an annual basis for the term of the contract through September 2021. Total commitments to Catalent of $1.0 million, for the period through September 2021, have been fulfilled as of the year ended December 31, 2020. Jubilant HollisterStier Manufacturing and Supply Agreement Pursuant to the Zyla Merger, the Company assumed a Manufacturing and Supply Agreement (the “Agreement”) with Jubilant HollisterStier LLC (“JHS”) pursuant to which the Company engaged JHS to provide certain services related to the manufacture and supply of SPRIX for the Company’s commercial use. Under the Agreement, JHS will be responsible for supplying a minimum of 75% of the Company’s annual requirements of SPRIX through July 30, 2022. The Company has agreed to purchase a minimum number of batches of SPRIX per calendar year from JHS over the term of the Agreement. Total commitments to JHS are $2.9 million through the period ending July 30, 2022 and are expected to be met. Legal Matters Glumetza Antitrust Litigation Antitrust class actions and related direct antitrust actions have been filed in the Northern District of California against the Company and several other defendants relating to our former drug Glumetza ® . The named class representatives in the currently pending actions include Meijer, Inc., Bi-Lo, LLC, Winn-Dixie Logistics, Inc., City of Providence, and KPH Healthcare Services, Inc. These class representatives seek to represent a putative class of direct purchasers of Glumetza. In addition, several retailers, including CVS Pharmacy, Inc., Rite Aid Corporation, Walgreen Co., the Kroger Co., the Albertsons Companies, Inc., H-E-B, L.P., and Hy-Vee, Inc., have filed substantially similar direct antitrust claims based on alleged assignments of claims from direct purchaser wholesalers. On December 23, 2019, the Company filed a motion to dismiss all claims in the actions. That motion was heard by the District Court on February 20, 2020. On March 5, 2020 the District Court issued an order denying the motion to dismiss. However, based on the order on the motion, claims previously filed by a putative class of end payor plaintiffs were voluntarily dismissed. On July 30, 2020, Humana Inc. also filed a complaint against the Company in the Northern District of California alleging similar claims related to Glumetza ® . On February 2, 2021, the District Court dismissed Humana’s state-law antitrust claims, but permitted Humana to proceed on its federal claims. On February 8, 2021, Humana refiled those state-law claims against the Company and several other defendants in the Superior Court for the State of California in the County of Alameda. These antitrust cases arise out of a Settlement and License Agreement (the Settlement) that the Company, Santarus, Inc. (Santarus) and Lupin Limited (Lupin) entered into in February 2012 that resolved patent infringement litigation filed by the Company against Lupin regarding Lupin’s Abbreviated New Drug Application for generic 500 mg and 1000 mg tablets of Glumetza. The antitrust plaintiffs allege, among other things, that the Settlement violated the antitrust laws because it allegedly included a “reverse payment” that caused Lupin to delay its entry in the market with a generic version of Glumetza. The alleged “reverse payment” is an alleged commitment on the part of the settling parties not to launch an authorized generic version of Glumetza for a certain period. The antitrust plaintiffs allege that the Company and its co-defendants, which include Lupin as well as Bausch Health (the alleged successor in interest to Santarus) are liable for damages under the antitrust laws for overcharges that the antitrust plaintiffs allege they paid when they purchased the branded version of Glumetza ® due to delayed generic entry. Plaintiffs seek treble damages for alleged past harm, attorneys’ fees and costs. In the federal litigations, fact and expert discovery have now closed, and the parties are currently briefing summary judgment motions. The federal court granted class certification in the direct purchaser action on August 15, 2020. In the event that the federal case proceeds to trial, that trial is expected to occur on or about October 2021. With respect to the newly-filed Humana case in California state court, the next step is for the defendants to file a motion to dismiss. The Company intends to defend itself vigorously in these matters. Securities Class Action Lawsuit and Related Matters On August 23, 2017, the Company, two individuals who formerly served as its chief executive officer and president, and its former chief financial officer were named as defendants in a purported federal securities law class action filed in the U.S. District Court for the Northern District of California (the District Court). The action ( Huang v. Depomed et al. , No. 4:17-cv-4830-JST, N.D. Cal.) alleges violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 relating to certain prior disclosures of the Company about its business, compliance, and operational policies and practices concerning the sales and marketing of its opioid products and contends that the conduct supporting the alleged violations affected the value of Company common stock and is seeking damages and other relief. In an amended complaint filed on February 6, 2018, the lead plaintiff (referred to in its pleadings as the Depomed Investor Group), which seeks to represent a class consisting of all purchasers of Company common stock between July 29, 2015 and August 7, 2017, asserted the same claims arising out of the same and similar disclosures against the Company and the same individuals as were involved in the original complaint. The Company and the individuals filed a motion to dismiss the amended complaint on April 9, 2018. On March 18, 2019, the District Court granted the motion to dismiss without prejudice, and the plaintiffs filed a second amended complaint on May 2, 2019. The second amended complaint asserted the same claims arising out of the same and similar disclosures against the Company and the same individuals as were involved in the original complaint. The Company and the individuals filed a motion to dismiss the second amended complaint on June 17, 2019, and the District Court granted that motion with prejudice on March 11, 2020. On April 9, 2020, the plaintiffs filed a notice of appeal with the United States Court of Appeals for the Ninth Circuit. The parties completed their briefing of the appeal on December 14, 2020. On March 1, 2021, the court granted to parties’ joint motion to stay the appeal pending settlement discussions. The Company believes that the action is without merit. The Company is unable to predict the outcome of this matter. In addition, five shareholder derivative actions were filed on behalf of the Company against its officers and directors for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, waste of corporate assets, and violations of the federal securities laws. The claims arise out of the same factual allegations as the purported federal securities class action described above. The first derivative action was filed in the Superior Court of California, Alameda County on September 29, 2017 ( Singh v. Higgins et al ., RG17877280). The second and third actions were filed in the Northern District of California on November 10, 2017 ( Solak v. Higgins et al ., No. 3:17-cv-6546-JST) and November 15, 2017 ( Ross v. Fogarty et al ., No. 3:17-cv-6592-JST). The fourth action was filed in the District of Delaware on December 21, 2018 ( Lutz v. Higgins et al , No. 18-2044-CFC). The fifth derivative action was filed in the Superior Court of California, Alameda County on January 28, 2019 ( Youse v. Higgins et al , No. HG19004409). On December 7, 2017, the plaintiffs in Solak v. Higgins, et al. voluntarily dismissed the action. On July 12, 2019, the Singh and Youse actions were consolidated. All of the derivative actions were stayed pending the resolution of the class action, and the stays have been extended pending the resolution of the appeal. The Company believes that these actions are without merit. The Company is unable to predict the outcome of these matters. Opioid-Related Request and Subpoenas As a result of the greater public awareness of the public health issue of opioid abuse, there has been increased scrutiny of, and investigation into, the commercial practices of opioid manufacturers generally by federal, state, and local regulatory and governmental agencies. In March 2017, Assertio Therapeutics received a letter from then-Sen. Claire McCaskill (D-MO), the then-Ranking Member on the U.S. Senate Committee on Homeland Security and Governmental Affairs, requesting certain information regarding Assertio Therapeutics’ historical commercialization of opioid products. Assertio Therapeutics voluntarily furnished information responsive to Sen. McCaskill’s request. Since 2017, Assertio Therapeutics has received and responded to subpoenas from the U.S. Department of Justice (DOJ) seeking documents and information regarding its historical sales and marketing of opioid products. Assertio Therapeutics has also received and responded to subpoenas or civil investigative demands focused on its historical promotion and sales of Lazanda, NUCYNTA, and NUCYNTA ER from various state attorneys general seeking documents and information regarding Assertio Therapeutics’ historical sales and marketing of opioid products. In addition, Assertio Therapeutics received and responded to a subpoena from the State of California Department of Insurance (CDI) seeking information relating to its historical sales and marketing of Lazanda. The CDI subpoena also seeks information on Gralise, a non-opioid product formerly in Assertio Therapeutics’ portfolio. In addition, Assertio Therapeutics received and responded to a subpoena from the New York Department of Financial Services seeking information relating to its historical sales and marketing of opioid products. The Company also from time to time receives and complies with subpoenas from governmental authorities related to investigations primarily focused on third parties, including healthcare practitioners. Assertio Therapeutics is cooperating with the foregoing governmental investigations and inquiries. Multidistrict Opioid Litigation A number of pharmaceutical manufacturers, distributors and other industry participants have been named in numerous lawsuits around the country brought by various groups of plaintiffs, including city and county governments, hospitals, individuals and others. In general, the lawsuits assert claims arising from defendants’ manufacturing, distributing, marketing and promoting of FDA-approved opioid drugs. The specific legal theories asserted vary from case to case, but the lawsuits generally include federal and/or state statutory claims, as well as claims arising under state common law. Plaintiffs seek various forms of damages, injunctive and other relief and attorneys’ fees and costs. For such cases filed in or removed to federal court, the Judicial Panel on Multi-District Litigation issued an order in December 2017, establishing a Multi-District Litigation court (MDL Court) in the Northern District of Ohio (In re National Prescription Opiate Litigation, Case No. 1:17-MD-2804). Since that time, more than 2,000 such cases that were originally filed in U.S. District Courts, or removed to federal court from state court, have been filed in or transferred to the MDL Court. Assertio Therapeutics is currently involved in a subset of the lawsuits that have been filed in or transferred to the MDL Court. Plaintiffs may file additional lawsuits in which the Company may be named. Plaintiffs in the pending federal cases involving the Company include individuals; county, municipal and other governmental entities; employee benefit plans, health insurance providers and other payors; hospitals, health clinics and other health care providers; Native American tribes; and non-profit organizations who assert, for themselves and in some cases for a putative class, federal and state statutory claims and state common law claims, such as conspiracy, nuisance, fraud, negligence, gross negligence, negligent and intentional infliction of emotional distress, deceptive trade practices, and products liability claims (defective design/failure to warn). In these cases, plaintiffs seek a variety of forms of relief, including actual damages to compensate for alleged personal injuries and for alleged past and future costs such as to provide care and services to persons with opioid-related addiction or related conditions, injunctive relief, including to prohibit alleged deceptive marketing practices and abate an alleged nuisance, establishment of a compensation fund, establishment of medical monitoring programs, disgorgement of profits, punitive and statutory treble damages, and attorneys’ fees and costs. No trial date has been set in any of these lawsuits, which are at an early stage of proceedings. The Company intends to defend itself vigorously in these matters. State Opioid Litigation Related to the cases in the MDL Court noted above, there have been hundreds of similar lawsuits filed in state courts around the country, in which various groups of plaintiffs assert opioid-drug related claims against similar groups of defendants. Assertio Therapeutics is currently named in a subset of those cases, including cases in Alabama, Arkansas, Mississippi, Missouri, Nevada, Pennsylvania, Texas and Utah. Plaintiffs may file additional lawsuits in which Assertio Therapeutics may be named. In the pending cases involving Assertio Therapeutics , plaintiffs are asserting state common law and statutory claims against the defendants similar in nature to the claims asserted in the MDL cases. Plaintiffs are seeking actual damages, disgorgement of profits, injunctive relief, punitive and statutory treble damages, and attorneys’ fees and costs. The state lawsuits in which the Company has been served are generally each at an early stage of proceedings (discovery will soon begin in one Alabama case, and trial in that case is scheduled for May 2022). The Company intends to defend itself vigorously in these matters. Insurance Litigation On January 15, 2019, the Company was named as a defendant in a declaratory judgment action filed by Navigators Specialty Insurance Company (Navigators) in the U.S. District Court for the Northern District of California (Case No. 3:19-cv-255). Navigators is the Company’s primary product liability insurer. Navigators was seeking declaratory judgment that opioid litigation claims noticed by the Company (as further described above under “Multidistrict Opioid Litigation” and “State Opioid Litigation”) are not covered by the Company’s life sciences liability policies with Navigators. On February 3, 2021, the Company entered into a Confidential Settlement Agreement and Mutual Release with Navigators to resolve the declaratory judgment action and the Company’s counterclaims. Pursuant to the Settlement Agreement, the parties settled and the coverage action was dismissed without prejudice. CAMBIA ® ANDA Litigation On July 16, 2020, the Company and APR Applied Pharma Research SA (APR), received notice from Patrin Pharma Inc. (Patrin) advising that Patrin had filed an Abbreviated New Drug Application (ANDA) seeking to market a generic version of CAMBIA ® 50 mg prior to the expiration of U.S. patents listed in the FDA “Orange Book” for CAMBIA (Orange Book Patents). The Orange Book Patents are licensed to the Company by APR. On August 27, 2020, the Company and APR filed a lawsuit against Patrin in the U.S. District Court for the Northern District of Illinois, Eastern Division, seeking an injunction to prevent approval of the Patrin ANDA. The lawsuit alleges that Patrin has infringed the Orange Book Patents by filing an ANDA with a Paragraph IV Certification seeking approval from the FDA to market a generic version of CAMBIA prior to the expiration of the patents. The commencement of the patent infringement suit stays or bars the FDA from approving Patrin’s ANDA for 30 months or until an earlier district court decision that each of the patents is invalid or not infringed. On September 18, 2020, Patrin filed its answer including affirmative defenses and counterclaims. On October 9, 2020, the Company and APR filed an answer to Patrin’s counterclaims. Trial has not yet been scheduled in the action. On January 21, 2021, the court stayed all case deadlines pending settlement discussions between the parties. On March 8, 2021, the Company entered into a confidential settlement agreement with Patrin. On March 10, 2021, the Court granted the parties’ agreed motion for entry of Judgment and Order of Permanent Injunction. This settlement concludes all ongoing ANDA litigation relating to CAMBIA. General The Company cannot reasonably predict the outcome of the legal proceedings described above, nor can the Company estimate the amount of loss, range of loss or other adverse consequence, if any, that may result from these proceedings or the amount of any gain in the event the Company prevails in litigation involving a claim for damages. As such the Company is not currently able to estimate the impact of the above litigation on its financial position or results of operations. The Company may from time to time become party to actions, claims, suits, investigations or proceedings arising from the ordinary course of its business, including actions with respect to intellectual property claims, breach of contract claims, labor and employment claims and other matters. The Company may also become party to further litigation in federal and state courts relating to opioid drugs. Although actions, claims, suits, investigations and proceedings are inherently uncertain and their results cannot be predicted with certainty, other than the matters set forth above, the Company is not currently involved in any matters that the Company believes may have a material adverse effect on its business, results of operations or financial

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANSThe Company's 401(k) Employee Savings Plan (the "401(k) Plan") is available to all U.S. employees meeting certain eligibility criteria. The 401(k) Plan was amended at the time of the Zyla Merger in May 2020. The Company may make discretionary matching contributions for employees of Assertio Therapeutics, Inc., and the percentage of elective deferral contributions matched, if any, shall be a percentage as determined by the Company. The Company has elected to make matching contributions for former employees of Zyla Life Sciences, Inc in an amount equal to 100% of elective deferral contributions that are not over 3% of compensation, plus 50% of elective deferral contributions that are over 3% of compensation but are not over 5% of compensation. The Company contributed cash of $0.2 million to the 401(k) Plan during each of the years ended December 31, 2020 and 2019. The Company's common stock is not an investment option available to participants in the 401(k) Plan.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company’s stock-based compensation generally includes stock options, restricted stock units (RSUs), performance share units (PSUs), and purchases under the Company’s employee stock purchase plan (ESPP). The following table reflects stock‑based compensation expense recognized in the Company’s Consolidated Statements of Comprehensive Income for the years ended December 31, 2020 and 2019 (in thousands): Years Ended December 31, 2020 2019 Cost of sales (excluding amortization of intangible assets) $ 92 $ 106 Research and development expenses 268 693 Selling, general and administrative expenses 9,565 9,797 Restructuring charges 999 — Total $ 10,924 $ 10,596 There is no stock‑based compensation recorded within inventory in any of the years presented. The recognized tax benefits on total stock-based compensation expense during the year ended December 31, 2020 was immaterial and during the year ended December 31, 2019 was $0.6 million. As of December 31, 2020, the Company had $2.7 million, $0.2 million, and $1.1 million of total unrecognized compensation expense related to RSUs, PSUs, and stock option grants, respectively, that will be recognized over a weighted average vesting period of 1.41 years, 0.89 years, and 1.87 years, respectively. The following table reflects assumptions used to calculate the fair value of option grants for the year ended December 31, 2020: 2020 Risk-free interest rate 0.20% - 0.35% Dividend yield —% Expected option term (in years) 3.4 - 5.0 Expected stock price volatility 80% The weighted average grant date fair value of options granted during the year ended December 31, 2020 was $0.41 per option share. No stock options were granted during the year ended December 31, 2019. No stock options were exercised during the year ended December 31, 2020, and stock options exercised during 2019 were immaterial. Total grant date fair value of options that vested during the years ended December 31, 2020 and 2019 was $0.7 million and $1.4 million, respectively. Employee Stock Purchase Plan The weighted average grant date fair value of stock purchase rights granted under the ESPP during the years ended December 31, 2020 and 2019 was $0.41 and $1.15, respectively. The following table reflects assumptions used to calculate the fair value of stock purchase rights granted under the ESPP for the years ended December 31, 2020 and 2019: 2020 2019 Employee Stock Purchase Plan Risk-free interest rate 0.09% - 0.18% 1.63% - 2.35% Dividend yield —% —% Expected term (in years) 0.5 0.5 Expected stock price volatility 85.8% - 142.3% 57.2% - 132.2% 2004 Equity Incentive Plan The Company’s 2004 Equity Incentive Plan (2004 Plan) was adopted by the Board of Directors and approved by the shareholders in May 2004. The 2004 Plan provides for the grant to employees of the Company, including officers, of incentive stock options, and for the grant of non-statutory stock options to employees, directors and consultants of the Company. The number of shares authorized under the 2004 Plan was 14,450,000 shares and there were no more shares available for future issuance at December 31, 2020. Generally, the exercise price of all incentive stock options and non-statutory stock options granted under the 2004 Plan must be at least 100% and 80%, respectively, of the fair value of the common stock of the Company on the grant date. The term of incentive and non-statutory stock options may not exceed 10 years from the date of grant. An option shall be exercisable on or after each vesting date in accordance with the terms set forth in the option agreement. The right to exercise an option generally vests over four years at the rate of at least 25% by the end of the first year and then ratably in monthly installments over the remaining vesting period of the option. The following tables reflects activity for the year ended December 31, 2020 under the 2004 Plan (dollar amounts in thousands): Shares Weighted- Weighted- Aggregate Options outstanding as of December 31, 2019 345,206 $ 7.29 Options granted — — Options exercised — — Options forfeited — — Options expired (221,706) 7.76 Options outstanding as of December 31, 2020 123,500 $ 6.43 1.9 $ — Options vested and expected as of vest at December 31, 2020 123,500 $ 6.43 1.9 $ — Options exercisable as of December 31, 2020 123,500 $ 6.43 1.9 $ — There were no restricted stock units granted under the 2004 Equity Incentive Plan. 2014 Omnibus Incentive Plan The Company’s 2014 Omnibus Incentive Plan (2014 Plan) was adopted by the Board of Directors and approved by the shareholders in May 2014, and subsequently amended and restated in June 2020 (2014 Amended Plan). The 2014 Amended Plan provides for the grant of stock options, stock appreciation rights, stock awards, cash awards and performance award to the employees, non-employee directors and consultants of the Company. Shares available for grant under the 2014 Amended Plan were increased during the year ended December 31, 2020 by 13 million shares. The number of shares authorized under the 2014 Amended Plan is 28,780,000 shares, of which 17,378,077 were available for future issuance at December 31, 2020. Incentive Stock Options Generally, the exercise price of all incentive stock options and non-statutory stock options granted under the 2014 Amended Plan must be the fair value of the common stock of the Company on the grant date. The term of incentive and non-statutory stock options may not exceed 10 years from the date of grant. An option shall be exercisable on or after each vesting date in accordance with the terms set forth in the option agreement. The right to exercise an option generally vests over four years at the rate of at least 25% by the end of the first year and then ratably in monthly installments over the remaining vesting period of the option. The following table reflects option activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted- Aggregate Options outstanding as of December 31, 2019 1,178,045 $ 12.64 Options granted 200,000 0.80 Options exercised — — Options forfeited (46,285) 9.17 Options expired (367,372) 13.68 Options outstanding as of December 31, 2020 964,388 $ 9.14 4.83 $ — Options vested and expected to vest as of December 31, 2020 964,388 $ 9.14 4.83 $ — Options exercisable as of December 31, 2020 716,501 $ 11.47 3.6 $ — Restricted Stock Units The following table reflects RSU activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted Non-vested performance-based restricted stock units as of December 31, 2019 2,936,715 $ 4.64 Granted 5,985,196 0.97 Vested (1,225,191) 4.77 Forfeited (2,199,758) 1.99 Non-vested restricted stock units as of December 31, 2020 5,496,962 $ 2.32 0.8 RSUs generally vest over three Performance-based Restricted Stock Units During the year ended December 31, 2019, the Company granted PSUs with an aggregate target award of 643,266 units and a weighted-average grant-date fair value of $8.2327 per unit. The PSU awards are measured exclusively to the relative total shareholder return (TSR) performance, which is measured against the three-year TSR of a custom index of companies. The actual number of shares awarded is adjusted to between zero and 200% of the target award amount based upon achievement in each of the three The following table reflects PSU activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted Aggregate Non-vested performance-based restricted stock units as of December 31, 2019 983,843 $ 8.11 Granted — — Vested — — Forfeited (78,007) 6.74 Non-vested performance-based restricted stock units as of December 31, 2020 905,836 $ 8.23 0.68 $ 324 Zyla Life Sciences Amended and Restated 2019 Stock-Based Incentive Compensation Plan The 2019 Zyla Plan was assumed in connection with the Zyla Merger, and pursuant to the Zyla Merger Agreement, each outstanding Zyla stock option was cancelled and converted into a stock option to purchase the Company’s Common Stock on the same terms and conditions with (1) the number of shares of Company Common Stock subject to each such option equal to (i) the number of shares of the common stock subject to the option multiplied by (ii) the Merger Exchange Ratio, which was 2.5, rounded, if necessary, to the nearest whole share and (2) an exercise price per share (rounded to the nearest whole cent) equal to the original exercise price of the Zyla stock option divided by (B) the Exchange Ratio. This resulted in the issuance of 5.0 million options with an average fair market value of $0.62 per share value, of which $0.4 million was recognized as merger consideration. The term of Zyla options may not exceed 10 years from the date of grant. An option shall be exercisable on or after each vesting date in accordance with the terms set forth in the option agreement. The right to exercise an option generally vests over three years at the rate of at least 33%, by the end of the first year and then ratably in monthly installments over the remaining vesting period of the stock option. The number of shares authorized under the 2019 Zyla Plan is 4,985,875 shares and there were no more shares available for future issuance as of December 31, 2020. The following table reflects option activity for the year ended December 31, 2020 under the 2019 Zyla Plan (dollar amounts in thousands): Shares Weighted Weighted- Aggregate Options outstanding as of December 31, 2019 — $ — Options granted 4,985,875 0.73 Options exercised — — Options forfeited (952,101) 0.70 Options expired (90,025) 1.12 Options outstanding as of December 31, 2020 3,943,749 0.73 9.3 — Options vested and expected to vest as of December 31, 2020 3,943,749 0.73 9.3 — Options exercisable as of December 31, 2020 1,933,604 0.80 9.5 — There were no restricted stock units granted under the 2019 Zyla Plan.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY Zyla Merger On May 20, 2020, Assertio completed the Zyla Merger pursuant to the Agreement and Plan of Merger dated March 16, 2020. Upon consummation of the Zyla Merger, each issued and outstanding share of Zyla common stock converted into 2.5 shares of Assertio Holding’s common stock (the Exchange Ratio). The Company issued 25.5 million in common shares related to the Zyla Merger, refer to “Note 2. Acquisitions”. Warrant Agreements Upon the Zyla Merger, the Company assumed Zyla’s outstanding Warrant Agreements which provides the holder the right to receive shares of the Company’s common stock. The warrants are exercisable at any time at an exercise price of $0.0004 per share, subject to certain ownership limitations including, with respect to Iroko and its affiliates, that no such exercise may increase the aggregate ownership of the Company’s outstanding common stock of such parties above 49% of the number of shares of its common stock then outstanding for a period of 18 months. All of the Company’s outstanding warrants have similar terms whereas under no circumstance may the warrants be net-cash settled. As such, all warrants are equity-classified . During December 2020, 6.1 million warrants were exercised and 6.1 million common shares were issued by the Company. The Company has 6.3 million warrant shares that remain outstanding. Employee Stock Purchase Plan In May 2004 the Employee Stock Purchase Plan (ESPP) was approved by the shareholders. The ESPP is qualified under Section 423 of the Internal Revenue Code, and allows eligible employees to purchase shares of the Company’s common stock through periodic payroll deductions. The price of the common stock purchased under the ESPP must be equal to at least 85% of the lower of the fair market value of the common stock on the commencement date of each offering period or the specified purchase date. The number of shares authorized for issuance under the ESPP as of December 31, 2020 was 4,200,000, of which 1,151,033 shares were available for future issuance. In 2020, the Company sold 182,726 shares of its common stock under the ESPP. The shares were purchased at a weighted‑average purchase price of $0.48 with proceeds of approximately $0.1 million. In 2019, the Company sold 168,790 shares of its common stock under the ESPP. The shares were purchased at a weighted‑average purchase price of $1.34 with proceeds of approximately $0.2 million. Option Exercises

NET (LOSS) INCOME PER SHARE

NET (LOSS) INCOME PER SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
NET (LOSS) INCOME PER SHARE	NET (LOSS) INCOME PER SHARE Basic net (loss) income per share is calculated by dividing the net (loss) income by the weighted-average number of shares of common stock outstanding during the period. Diluted net (loss) income per share is calculated by dividing the net income by the weighted-average number of shares of common stock outstanding during the period, plus potentially dilutive common shares, consisting of stock options and convertible debt. The 6,339,765 shares of common stock issuable upon the exercise of warrants are included in the number of outstanding shares used for the computation of basic and diluted loss per share for the year ended December 31, 2020 (see Note 15. Shareholders’ Equity). The Company uses the treasury-stock method to compute diluted earnings per share with respect to its stock options and equivalents. The Company uses the if-converted method to compute diluted earnings per share with respect to its convertible debt. For purposes of this calculation, options to purchase stock are considered to be potential common shares and are only included in the calculation of diluted net (loss) income per share when their effect is dilutive. The following table reflects the calculation of basic and diluted earnings per common share for the years ended December 31, 2020 and 2019 (in thousands, except for per share amounts): Year ended December 31, 2020 2019 Basic net income (loss) per share Net loss $ (28,144) $ (217,201) Weighted average common shares outstanding 104,835 70,716 Basic net loss per share $ (0.27) $ (3.07) Diluted net income (loss) per share Net loss $ (28,144) $ (217,201) Weighted average common shares outstanding 104,835 70,716 Add: effect of dilutive securities — — Denominator for diluted loss per share 104,835 70,716 Diluted net loss per share $ (0.27) $ (3.07) The following table reflects outstanding potentially dilutive shares of common stock that are not included in the computation of diluted net income (loss) per share because, to do so would be anti-dilutive for the years ended December 31, 2020, and 2019 (in thousands): Year ended December 31, 2020 2019 2.50% Convertible Notes due 2021 1,344 13,895 5.00% Convertible Notes due 2024 6,831 14,895 Stock options and equivalents 10,620 6,486 Total potentially dilutive common shares 18,795 35,276

DISPOSITIONS

DISPOSITIONS	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
DISPOSITIONS	DISPOSITIONS Sale of Gralise On December 12, 2019, the Company entered into an Asset Purchase Agreement with Golf Acquiror LLC, an affiliate of Alvogen, Inc. (Alvogen) to divest its rights, title and interest in and to Gralise, including certain related assets, to Alvogen. The transaction subsequently closed on January 10, 2020. At closing, the Company received $78.6 million, including a $75.0 base purchase price and a preliminary positive inventory adjustment equal to $3.6 million. In addition, the Company was entitled to receive 75% of Alvogen’s first $70.0 million of Gralise net sales after closing, as contingent consideration. Alvogen has also assumed, pursuant to the terms of the Asset Purchase Agreement, certain contracts, liabilities and obligations of the Company relating to Gralise, including those related to manufacturing and supply, post-market commitments and clinical development costs. On June 3, 2020 Alvogen agreed to disburse the contingent consideration due to satisfy its remaining obligations to the Company pursuant to the Asset Purchase Agreement. As consideration for the early disbursement, the Company agreed to reduce the total payments due from Alvogen by $0.9 million, which was recognized as an adjustment to the gain on the sale of Gralise in the Consolidated Statement of Comprehensive Income during the year ended December 31, 2020. During the year ended December 31, 2020, the Company collected a total of $51.6 million from Alvogen in contingent consideration receivable for the sale of Gralise. Pursuant to ASC 205-20, Presentation of Financial Statements— Discontinued Operations, Gralise did not meet the criteria of a discontinued operation as it was not considered a component of an entity that comprises operations and cash flows that can be clearly distinguished, operationally and for financial reporting purposes, from the rest of the Company, nor did it represent a strategic shift of the Company. The Company accounted for the divestiture under ASC 610-20 Other Income - Derecognition of Nonfinancial Assets . During the year ended December 31, 2020, the Company recognized a gain of $126.6 million in Other income on the Company’s Consolidated Statements of Comprehensive Income composed of the $78.6 million in upfront consideration received and $51.6 million in contingent consideration settled and $3.6 million in inventory transferred. In addition, the Company recognized co-promotion service income of approximately $1.3 million and Co-promotion services were completed as of the first quarter of 2020. Termination of Slán Agreements On November 7, 2017, the Company entered into an agreement with Slán Medicinal Holdings Limited (Slán) under which it (i) acquired from Slán certain rights to market the specialty drug, long-acting cosyntropin in the U.S. and (ii) divested to Slán all of its rights to Lazanda® (fentanyl) Nasal Spray CII. As consideration for this acquisition, the Company provided the seller all of the rights and obligations, as defined under the arrangement, associated with Lazanda and together with $5.0 million in cash to Slán. As outlined in the Slán Agreements, each party would support the development, including clinical development, of the licensed product and efforts to obtain regulatory approval of the initial NDA. Subsequent to approval of the initial NDA, Assertio and Slán would share in the net sales of long-acting cosyntropin for a 10-year period (after which time the product will revert back to Slán). As of December 31, 2019, the Company had $2.0 million of reimbursable development expenses in Prepaid and other current assets on the Company’s Consolidated Balance Sheet. On February 6, 2020, the Company entered into an amended agreement with Eolas Pharma Teoranta (Eolas), an affiliate of Slán. Pursuant to the amendment the license granted to the Company for the commercialization of long-acting cosyntropin was terminated and the Company received $2.0 million in settlement for the receivable for reimbursable development expenses. Additionally, the Company may receive up to $10.0 million in future payments based upon commercial sales of long-acting cosyntropin if Eolas successfully obtains regulatory approval for and commercializes the product. Sale of NUCYNTA On February 6, 2020, the Company entered into a Purchase Agreement with Collegium, to divest its remaining rights, title and interest in and to the NUCYNTA franchise of products from the Company, and assumed certain contracts, liabilities and obligations of the Company relating to the NUCYNTA products, including those related to manufacturing and supply, post-market commitments and clinical development costs. The transaction subsequently closed on February 13, 2020. The Company received $367.9 million in net proceeds, which consisted of $375.0 million in base purchase price, plus $6.0 million in preliminary positive inventory value and less $13.1 million for royalties paid to the Company by Collegium between January 1, 2020 and February 11, 2020 pursuant to the Final Commercialization Agreement Payment Value of the Asset Purchase Agreement. In connection with the sale, the Company entered into a third-party consent agreement which requires two lump sum payments of $4.5 million each payable in 2021 and 2022 subject to Collegium achieving certain net sales in 2020 and 2021, respectively. Since January 9, 2018, Collegium has been responsible for the commercialization of NUCYNTA in the U.S., including sales and marketing, and the Company received royalties based on certain net sales thresholds, in accordance with the Pursuant to ASC 205-20, the divestiture of NUCYNTA did not meet the criteria of a discontinued operation as it was not considered a strategic shift. The Company accounted for the divestiture under ASC 610-20 Other Income - Derecognition of Nonfinancial Assets

FAIR VALUE

FAIR VALUE	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE 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. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. • Level 1: Quoted prices in active markets for identical assets or liabilities. • Level 2: Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The following tables reflect the fair value hierarchy for Company financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019 (in thousands): December 31, 2020 Financial Statement Classification Level 1 Level 2 Level 3 Total Assets: Money market funds Cash and cash equivalents $ 77 $ — $ — $ 77 Total $ 77 $ — $ — $ 77 Liabilities: Short-term contingent consideration Contingent consideration liability $ — $ — $ 6,776 $ 6,776 Long-term contingent consideration Contingent consideration liability — — 31,776 31,776 Total $ — $ — $ 38,552 $ 38,552 December 31, 2019 Financial Statement Classification Level 1 Level 2 Level 3 Total Assets: Collegium warrants Investments $ — $ 9,629 $ — $ 9,629 Total $ — $ 9,629 $ — $ 9,629 Liabilities: Contingent consideration Contingent consideration liability $ — $ — $ 168 $ 168 Total $ — $ — $ 168 $ 168 Cash and Cash Equivalents Cash equivalents consisted of money market funds with overnight liquidity and no stated maturities. The Company classified cash equivalents as Level 1, due to their short-term maturity, and measured the fair value based on quoted prices in active markets for identical assets. Contingent Consideration Pursuant to the Zyla Merger, the Company assumed a contingent consideration obligation which is measured at fair value. The Company has obligations to make contingent consideration payments for future royalties to Iroko based upon annual INDOCIN Product net sales over $20.0 million. The Company recorded the fair value of the contingent consideration liability, based on the likelihood of contingent earn-out payments. The earn-out payments are remeasured to fair value each reporting period and cash payments made, if required, in May and November of each year. The Company classified the acquisition-related contingent consideration liabilities to be settled in cash as Level 3, due to the lack of relevant observable inputs and market activity. As of December 31, 2020, INDOCIN Product contingent consideration was $38.4 million with $6.8 million classified as short-term and $31.6 million million classified as long-term contingent consideration, respectively, in the Consolidated Balance Sheet. The fair value of the contingent consideration at the Zyla Merger date was determined using an option pricing model under the income approach based on estimated INDOCIN Product revenues over 10 years and discounted to present value. The significant assumptions used in the calculation of the fair value as of December 31, 2020 included revenue volatility of 35.0%, discount rate of 6.0%, credit spread of 5.9% and updated projections of future INDOCIN Product revenues. The fair value of the contingent consideration is remeasured each reporting period, with changes in the fair value resulting from a change in the underlying inputs are recognized within Selling, general and administrative expenses on the Consolidated Statement of Comprehensive Income until the contingent consideration is settled. Contingent consideration related to CAMBIA was $0.2 million as of December 31, 2020 and 2019. The following table summarizes changes in fair value that are measured on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2020, and 2019 (in thousands): December 31, 2020 2019 Fair value, beginning of the period $ 168 $ 1,038 Contingent consideration acquired with Zyla Merger 39,900 — Change in fair value of contingent consideration recorded within costs and expenses 1,500 (983) Cash payment related to contingent consideration (3,016) — Changes in fair value of contingent consideration recorded in interest expense — 113 Total $ 38,552 $ 168 Investments The fair value of the warrants to purchase Collegium’s common stock was calculated using the Black-Scholes option pricing model. As of December 31, 2019, the significant inputs included the fair value of Collegium’s common stock of $16.33, an expected term of 2.61 years and a risk-free rate of $0.27%. The expected term was based on the remaining contractual period of 2.61 years, and the volatility was determined using Collegium’s historical common stock volatility over the expected term. In May 2020, the Company sold the Collegium warrants for an aggregate purchase price of $6.0 million to Armistice Capital Mater Fund, Ltd. As a result, the Company derecognized the carrying value of $9.6 million of the financial asset and recognized a net loss of approximately $3.6 million, recorded within other (expense) income, net on the Consolidated Statement of Comprehensive Income, during the year ended December 31, 2020. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the years ended December 31, 2020 and 2019. The outstanding principal amount of the Secured Notes (as defined in “Note 9. Debt”) approximate their fair value as of December 31, 2020 and represents a Level 2 valuation. When determining the estimated fair value of the Company’s debt, the Company uses a commonly accepted valuation methodology and market-based risk measurements that are indirectly observable, such as credit risk.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table reflects Loss before income taxes by source for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 U.S. $ (45,327) $ (222,484) Outside the U.S. (186) — Net loss before income taxes $ (45,513) $ (222,484) The following table reflects benefit provision for income taxes for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Current: Federal $ (9,100) $ (1,231) State 155 1,715 Total current taxes $ (8,945) $ 484 Deferred: Federal $ (7,037) $ (5,767) State (1,387) — Total deferred taxes (8,424) (5,767) Total benefit for income taxes $ (17,369) $ (5,283) The following table reflects a reconciliation of income taxes at the statutory federal income tax rate to the actual tax rate included in the Statements of Comprehensive Income for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Tax at federal statutory rate $ (9,558) $ (46,722) State tax, net of federal benefit 276 (3,845) Goodwill impairment 3,661 — Disallowed officers' compensation 818 — Non-deductible transaction cost 451 — Non-deductible meals and entertainment 148 129 Stock based compensation 17 2,038 Change in valuation allowance (13,029) 48,943 Uncertain tax provisions (190) (5,758) Non-deductible other expense 37 5,837 Research credit — (138) Intraperiod tax allocations — (5,767) Total tax benefit $ (17,369) $ (5,283) On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security (“CARES”) Act was enacted. The CARES ACT was a massive tax-and-spending package intended to provide additional economic relief to address the impact of the COVID-19 pandemic. The CARES Act, among other business tax provisions, included legislative changes and updates to net operating losses (NOLs), interest disallowance, and depreciation for qualified improvement property. The Company considered the income tax accounting implications from CARES Act to the Company’s income tax provision calculation for the year ended December 31, 2020. Prior to the enactment of the CARES Act, federal NOLs generated after December 31, 2017 could not be carried back to prior tax years. Upon the enactment of the CARES Act, federal NOLs generated in tax years 2018, 2019, and 2020 can now be carried back to the previous five tax years without taxable income limitation. The Company is intending to carryback the 2020 federal taxable loss to the 2018 and 2019 tax years to offset taxable income (and federal taxes paid) for those two tax years. The estimated cash tax refund is approximately $8.3 million, which should be received in 2021. During the year ended December 31, 2020, the Company recorded an income tax benefit of $17.4 million, principally due to the carryback of the Company’s 2020 federal NOL to its 2018 and 2019 tax years under the NOL carryback provisions enacted as part of the CARES Act mentioned above and the current year reversal of valuation allowance related to the utilization of the Company’s deferred tax assets (“DTA”) to offset the deferred tax liabilities (“DTL”) of Zyla recorded through acquisition accounting. During 2019, the Company recorded an income tax benefit of $5.3 million, principally due to the release of FASB Interpretation No. 48, Accounting for Uncertainties in Income Taxes (FIN 48) liabilities based on lapsing of statute of limitation, and tax benefits being recorded as a result of intraperiod tax allocation from the Company’s Convertible Note Exchange. Utilization of the Company’s net operating loss and credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations provided by the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. Deferred income taxes reflect the temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The following table reflects significant components of the Company’s deferred tax assets are as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating losses $ 81,471 $ 5,885 Tax credit carryforwards 3,360 1,411 Intangible assets — 82,582 Stock-based compensation 2,999 1,907 Operating lease liabilities 1,248 1,577 Fixed assets 1,315 — Reserves and other accruals not currently deductible 20,652 9,729 Disallowed interest carryforward 15,496 718 Total deferred tax assets $ 126,541 $ 103,809 Valuation allowance for deferred tax assets (103,906) (90,820) $ 22,635 $ 12,989 Deferred tax liabilities: Intangible assets $ (21,739) $ — Convertible debt (459) (12,247) Fixed Assets — (109) Operating lease right-of-use assets (437) (633) Net deferred tax liability $ — $ — During the year ended December 31, 2020, the Company recorded a valuation allowance of $103.9 million to offset, in full, the benefit related to its net deferred tax assets as of December 31, 2020 because realization of the future benefits is uncertain. The Company reviewed both positive evidence such as, but not limited to, the projected availability of future taxable income and negative evidence such as the history of cumulative losses in recent years. The Company will continue to assess the realizability of its deferred tax assets on a quarterly basis and assess whether an additional reserve or a release of the valuation allowance is required in future periods. The valuation allowance increased $13.1 million to $103.9 million during the year ended December 31, 2020 and increased $48.9 million to $90.8 million during the year ended December 31, 2019. As of December 31, 2020, the Company had federal NOLs of $288.1 million with no expiration and $40.1 million expiring in varying amounts from 2032 through 2036. NOL carryforwards for state income tax purposes are $181.9 million, which begin to expire in 2021. Utilization of the Company’s NOL and credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations provided by the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. The Company does not have any significant federal or state tax examinations in process as of December 31, 2020. The federal and state statute of limitations remains open primarily for the 2017 through 2019 tax years. The California statute of limitations is open for the 2007 through 2019 tax years. The following table reflects activity related to the Company’s unrecognized tax benefits for the years ended December 31, 2020 and 2019 (in thousands): Unrecognized tax benefits—December 31, 2018 $ 16,064 Increases related to current year tax positions 212 Changes in prior year tax positions (232) Decreases related to lapse of statutes (12,011) Unrecognized tax benefits—December 31, 2019 $ 4,033 Increases related to current year tax positions 194 Changes in prior year tax positions (2) Decreases related to lapse of statutes (124) Unrecognized tax benefits—December 31, 2020 $ 4,101 The total amount of unrecognized tax benefit that would affect the effective tax rate is $4.1 million as of December 31, 2020 and $4.0 million as of December 31, 2019. The Company does not expect a significant change to its unrecognized tax benefits over the next twelve months. The unrecognized tax benefits may increase or change during the next year for items that arise in the ordinary course of business.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On February 9, 2021, the Company completed a registered direct offering with certain institutional investors and accredited investors to sell 22,600,000 shares of its common stock at a purchase price of $0.62 per share. The gross proceeds to the Company from the offering were approximately $14.0 million. After placement agent fees and other offering expenses payable by the Company, the Company received net proceeds of approximately $13.1 million. On February 12, 2021, the Company completed a registered direct offering with certain institutional investors and accredited investors to sell 35,000,000 shares of its common stock at a purchase price of $0.98 per share. The gross proceeds to the Company from the offering were approximately $34.3 million. After placement agent fees and other offering expenses payable by the Company, the Company received net proceeds of approximately $32.2 million. The Company intends to use proceeds from both offerings for general corporate purposes, including general working capital.

SCHEDULE II_ VALUATION AND QUAL

SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS	SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS (in thousands) Additions Description Balance at Charged as a Reduction to Revenue (1) Deductions (2) Balance at End of Year (3) Sales & return allowances, discounts, chargebacks and rebates: Year ended December 31, 2020 $ 60,183 132,340 (128,081) $ 64,442 Year ended December 31, 2019 $ 76,401 $ 163,261 $ (179,479) $ 60,183 Description Balance at Additions Deductions Balance at Deferred tax asset valuation allowance: December 31, 2020 (4) $ 90,820 $ 29,833 $ (16,747) $ 103,906 December 31, 2019 (5) $ 41,905 $ 48,915 $ — $ 90,820 (1) Includes $33.3 million provision for liabilities assumed from the Zyla Merger. (2) Deductions to sales discounts and allowances relate to discounts or allowances, returns, chargebacks and rebates actually taken or paid. (3) Balance includes allowances for cash discounts of $1.3 million and $1.2 million as of December 31, 2020 and 2019, respectively, for prompt payment recognized in Accounts Receivable, net on the Company’s Consolidated Balance Sheets. (4) The Company recorded a valuation allowance of $13.1 million during 2020. The addition is primarily attributable to the increase in the DTA for the portion of the 2020 net operating loss that is carried forward to future years and the Zyla Merger. The deduction is related to the DTL recorded in the opening balance sheet for Zyla and the carryback of the 2020 net operating loss carryback to the 2018 and 2019 years. (5) The Company recorded a valuation allowance of $48.9 million during 2019.

ORGANIZATION AND SUMMARY OF S_2

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Preparation The Company’s consolidated financial statements are prepared in accordance with United States (“U.S.”) generally accepted accounting principles (U.S. GAAP) and U.S. Securities and Exchange Commission (SEC) regulations for annual reporting. In connection with the preparation of the financial statements for the year ended December 31, 2020, the Company evaluated whether there were conditions and events, considered in the aggregate, which raised substantial doubt as to the entity's ability to continue as a going concern within twelve months after the date of the issuance of these financial statements noting that there did not appear to be evidence of substantial doubt of the entity's ability to continue as a going concern.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Estimates are used when accounting for amounts recorded in connection with acquisitions, including initial fair value determinations of assets and liabilities as well as subsequent fair value measurements. Additionally, estimates are used in determining items such as sales discounts and returns, depreciable and amortizable lives, share-based compensation assumptions and taxes on income. Although management believes these estimates are based upon reasonable assumptions within the bounds of its knowledge of the Company, actual results could differ materially from these estimates.
Segment Information	Segment Information The Company manages its business within one reportable segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. To date, substantially all of the Company’s revenues from product sales are related to sales in the U.S.
Cash, Cash Equivalents	Cash, Cash Equivalents Cash and cash equivalents include cash in readily available checking and money market funds. We consider all highly liquid investments purchased with a maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents are carried at cost, which approximates fair value.
Accounts Receivable	Accounts Receivable Trade accounts receivable are recorded net of allowances for cash discounts for prompt payment. To date the Company has not recorded a bad debt allowance since the majority of its product revenue comes from sales to a limited number of financially sound companies who have historically paid their balances timely. The need for a bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers or any other potential circumstances that could result in bad debt.
Inventories	Inventories Inventories are stated at the lower of cost or net realizable value with cost determined by specific manufactured lot. Inventories consist of costs of the active pharmaceutical ingredient, contract manufacturing and packaging costs. Additionally,
Investments	Investments Assertio received warrants to purchase Collegium stock in conjunction with its November 2018 amendment to the Collegium Commercialization Agreement. Such warrants were measured at fair value with changes in fair value recorded in Other (loss) gain on the Company’s Consolidated Statements of Comprehensive Income during the year ended December 31, 2019. The Collegium warrants were sold during the year ended December 31, 2020.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets, as follows: Furniture and office equipment 3 - 5 years Machinery and equipment 5 - 7 years Laboratory equipment 3 - 5 years Leasehold improvements Shorter of estimated useful life or lease term
Intangible And Long-Lived Assets	Intangible Assets (other than goodwill) Intangible assets, other than goodwill, consist of product rights that are accounted for as definite-lived intangible assets subject to amortization. The Company determines the fair value of acquired intangible assets as of the acquisition date. Discounted cash flow models are typically used in these valuations, which require the use of significant estimates and assumptions, including but not limited to, developing appropriate discount rates and estimating future cash flows from product sales and related expenses. The fair value recorded is amortized on a straight-line basis over the estimated useful life of the asset. The Company estimated the useful life of the assets by considering competition by products prescribed for the same indication, the likelihood and estimated future entry of non-generic and generic competition for the same or similar indication and other related factors. Impairment of Long-lived Assets The Company evaluates long-lived assets, including property and equipment and product rights, for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss is calculated as the excess of the carrying amount over the fair value. Estimating future cash flows and fair value related to an intangible asset involves significant estimates and assumptions. If the Company’s assumptions are not correct, there could be an impairment loss or, in the case of a change in the estimated useful life of the asset, a change in amortization expense. As of December 31, 2020, the Company determined there were indicators of impairment present related to the declining revenues due to the adverse impact of COVID-19 on our business as well as unfavorable changes in product payor mix, resulting in the Company’s announcement of the December 2020 Plan. These factors contributed to higher operating losses and cash used by operating activities during the year ended December 31, 2020, as compared to the prior year. In addition, during the fourth quarter of 2020, the Company’s market capitalization declined from approximately $72.0 million as of September 30, 2020 to $38.0 million as of December 31, 2020. As a result of these recent events, the Company determined indicators of impairment were present and, accordingly, performed a test for recoverability of long-lived assets to be held and used pursuant to ASC 360, Impairment Testing: Long Lived Assets Classified as Held and Used. After grouping the long-lived assets, including purchased developed technology and trademarks, at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other assets and liabilities, the Company estimated the future net undiscounted cash flows expected to be generated from the use of the long-lived asset group and its eventual disposition. The Company then compared the estimated undiscounted cash flows to the carrying amount of the long-lived asset group. Based on this test, the
Acquisitions	Acquisitions The Company accounts for acquired businesses using the acquisition method of accounting under ASC 805, Business Combinations (ASC 805), which requires that assets acquired and liabilities assumed be recorded at date of acquisition at their respective fair values. The fair value of the consideration paid, including contingent consideration, is assigned to the underlying net assets of the acquired business based on their respective fair values. Any excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Significant judgments are used in determining the estimated fair values assigned to the assets acquired and liabilities assumed and in determining estimates of useful lives of long-lived assets. Fair value determinations and useful life estimates are based on, among other factors, estimates of expected future net cash flows, estimates of appropriate discount rates used to present value expected future net cash flows, the assessment of each asset’s life cycle, and the impact of competitive trends on each asset’s life cycle and other factors. These judgments can materially impact the estimates used to allocate acquisition date fair values to assets acquired and liabilities assumed and the resulting timing and amounts charged to, or recognized in current and future operating results. For these and other reasons, actual results may vary significantly from estimated results. Any changes in the fair value of contingent consideration resulting from a change in the underlying inputs is recognized in operating expenses until the contingent consideration arrangement is settled. Changes in the fair value of contingent consideration resulting from the passage of time are recorded within interest expense until the contingent consideration is settled. If the acquired net assets do not constitute a business under the acquisition method of accounting, the transaction is accounted for as an asset acquisition and no goodwill is recognized. In an asset acquisition, the amount allocated to acquired in-process research and development with no alternative future use is charged to expense at the acquisition date.
Goodwill	Goodwill Under the purchase method of accounting pursuant to ASC 805 , Goodwill is calculated as the excess of the purchase price over the fair value of the assets acquired and liabilities assumed. Goodwill, which is not tax-deductible, is recognized within other long-term assets, and is not amortized but subject to an annual review for impairment. Goodwill is tested for impairment at the reporting unit level at least annually or when a triggering event occurs that could indicate a potential impairment by assessing qualitative factors or performing a quantitative analysis in determining whether it is more likely than not that the fair value of net assets are below their carrying amounts. A reporting unit is the same as, or one level below, an operating segment. Our operations are currently comprised of a single reporting unit. As of December 31, 2020, the Company determined, due to declining revenues and a decrease in its market capitalization, that it was more likely than not that the fair value of net assets are below their carrying amounts and, therefore, the Company performed the required goodwill impairment test under ASC 350, I ntangibles - Goodwill and Other . First, the Company estimated the fair value of the reporting unit to which goodwill is assigned using a combination of the income and market approach. The Company then compared the carrying amount of the reporting unit, including goodwill, to its fair value. Since the fair value was less than the reporting unit’s carrying amount, the Company calculated the goodwill impairment as the difference between the reporting unit’s fair value and the carrying amount, not to exceed the carrying amount of goodwill. Accordingly, the Company recorded an impairment charge of $17.4 million, recognized within total costs and expenses in the Consolidated Statement of Comprehensive Income, to impair the carrying amount of goodwill as of December 31, 2020.
Contingent Consideration	Contingent Consideration The Company assumed a contingent consideration liability upon its merger with Zyla. The liability assumed included contingent consideration related to royalties payable in the form of an earnout provision based on INDOCIN Product revenue estimates and a probability assessment with respect to the likelihood of achieving the level of net sales that would trigger the contingent payment. The fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement as defined in fair value measurement accounting. The key assumptions in determining the fair value are the discount rate and the probability assigned to the potential milestones being achieved. At each reporting date, the Company will re-measure the contingent consideration obligation to estimated fair value which is recognized as change in fair value of contingent consideration payable within operating expenses in the Company’s Consolidated Statements of Operations.
Revenue Recognition	Revenue Recognition Under ASC 606, Revenue from Contracts with Customers (ASC 606), the Company recognizes revenue when its customer obtains control of the promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation, when (or as) the performance obligation is satisfied. The Company assesses the term of the contract based upon the contractual period in which the Company and Collegium have enforceable rights and obligations. Variable consideration arising from sales or usage-based royalties, promised in exchange for a license of the Company’s Intellectual Property, is recognized at the later of (i) when the subsequent product sales occur or (ii) the performance obligation, to which some or all of the sales-based royalty has been allocated, has been satisfied. The Company recognizes a contract asset relating to its conditional right to consideration for completed performance obligations. Accounts receivable are recorded when the right to consideration becomes unconditional. A contract liability is recorded for payments received in advance of the related performance obligation being satisfied under the contract. Product Sales The Company sells commercial products to wholesale distributors and specialty pharmacies. Product sales revenue is recognized when title has transferred to the customer and the customer has assumed the risks and rewards of ownership, which typically occurs on delivery to the customer. The Company’s performance obligation is to deliver product to the customer, and the performance obligation is completed upon delivery. The transaction price consists of a fixed invoice price and variable product sales allowances, which include rebates, discounts and returns. Product sales revenues are recorded net of applicable sales tax and reserves for these product sales allowances. Receivables related to product sales are typically collected one Product Sales Allowances - The Company considers products sales allowances to be variable consideration and estimates and recognizes product sales allowances as a reduction of product sales in the same period the related revenue is recognized. Product sales allowances are based on actual or estimated amounts owed on the related sales. These estimates take into consideration the terms of the Company’s agreements with customers, historical product returns, rebates or discounts taken, estimated levels of inventory in the distribution channel, the shelf life of the product and specific known market events, such as competitive pricing and new product introductions. The Company uses the most likely method in estimating product sales allowances. If actual future results vary from the Company’s estimates, the Company may need to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustment. The Company’s sales allowances include: Product Returns - The Company allows customers to return product for credit with respect to that product within six months before and up to 12 months after its product expiration date. The Company estimates product returns and associated credit on Zipsor, CAMBIA, NUCYNTA, Gralise, Lazanda and products acquired from Zyla, INDOCIN Products, ZORVOLEX, VIVLODEX and OXAYDO. Estimates for returns are based on historical return trends by product or by return trends of similar products, taking into consideration the shelf life of the product at the time of shipment, shipment and prescription trends, estimated distribution channel inventory levels and consideration of the introduction of competitive products. The Company did not assume financial responsibility for returns of NUCYNTA previously sold by Janssen Pharma or Lazanda product previously sold by Archimedes Pharma US Inc. Under the Commercialization Agreement with Collegium for NUCYNTA, the divestiture of Lazanda to Slán and the divestiture of Gralise to Alvogen, the Company is only financially responsible for product returns for product that were sold by the Company, which are identified by specific lot numbers. Shelf lives, from the respective manufacture dates, for the Company’s products range from 24 months to 48 months. Because of the shelf life of the Company’s products and its return policy of issuing credits with respect to product that is returned within six months before and up to 12 months after its product expiration date, there may be a significant period of time between when the product is shipped and when the Company issues credit on a returned product. Accordingly, the Company may have to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustments. Wholesaler and Pharmacy Discounts—The Company offers contractually determined discounts to certain wholesale distributors and specialty pharmacies that purchase directly from it. These discounts are either taken off invoice at the time of shipment or paid to the customer on a quarterly basis one Prompt Pay Discounts - The Company offers cash discounts to its customers (generally 2% of the sales price) as an incentive for prompt payment. Based on the Company’s experience, the Company expects its customers to comply with the payment terms to earn the cash discount. Patient Discount Programs - The Company offers patient discount co-pay assistance programs in which patients receive certain discounts off their prescriptions at participating retail and specialty pharmacies. The discounts are reimbursed by the Company to program administrators approximately one month after the prescriptions subject to the discount are filled. Medicaid Rebates - The Company participates in Medicaid rebate programs, which provide assistance to certain low income patients based on each individual state’s guidelines regarding eligibility and services. Under the Medicaid rebate programs, the Company pays a rebate to each participating state, generally two Chargebacks - The Company provides discounts to authorized users of the Federal Supply Schedule (FSS) of the General Services Administration under an FSS contract with the Department of Veterans Affairs and 340B eligible entities. These federal and 340B entities purchase products from the wholesale distributors at a discounted price, and the wholesale distributors then charge back to the Company the difference between the current retail price and the price the federal entity paid for the product. Managed Care Rebates - The Company offers discounts under contracts with certain managed care providers. The Company generally pays managed care rebates one Medicare Part D Coverage Gap Rebates - The Company participates in the Medicare Part D Coverage Gap Discount Program under which it provides rebates on prescriptions that fall within the “donut hole” coverage gap. The Company generally pays Medicare Part D Coverage Gap rebates two Royalties and Milestone Revenue For arrangements that include sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company currently has the right to receive royalties based on sales of CAMBIA in Canada, which are recognized as revenue when the related sales occur as there are no continuing performance obligations by the Company under those agreements. For arrangements that include milestones, the Company recognizes such revenue using the most likely method. At the end of each reporting period, the Company re-evaluates the probability or achievement of any potential milestone and any related constraints, and if necessary, adjusts its estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue in the period of adjustment.
Leases	Leases The Company adopted ASC 842, Leases (ASC 842), on January 1, 2019 using the modified retrospective approach. There was no adjustment to the Company's opening balance of accumulated deficit resulting from the adoption of this guidance. In addition, the Company elected the package of practical expedients, which among other things, allowed for the carryforward of the historical lease classification. The Company did not elect the hindsight practical expedient to determine the reasonably certain lease term for existing leases. Prior to the adoption of ASC 842, the Company accounted for its operating leases in accordance with ASC 840. Under ASC 840, only capital leases were recognized on the balance sheet and therefore the Company’s operating leases were reflected in the financial statement footnotes. The adoption of ASC 842 did not materially affect the Company’s Consolidated Comprehensive Income. The Company assesses contracts for lease arrangements at inception. Operating right-of-use (ROU) assets and liabilities are recognized at the lease commencement date equal to the present value of future lease payments using the implicit, if readily available, or incremental borrowing rate based on the information readily available at the commencement date. ROU assets include any lease payments as of commencement and initial direct costs but exclude any lease incentives. Lease and non-lease components are generally accounted for separately and the Company recognizes operating lease expense straight-line over the term of the lease. Operating leases are included in other long-term assets, other current liabilities other long term liabilities The Company accounts for operating leases with an initial term of 12 months or less on a straight-line basis over the lease term in the Consolidated Statements of Comprehensive Income.
Stock-Based Compensation	Stock Based Compensation The Company’s stock-based compensation generally includes stock options, restricted stock units (RSUs), performance share units (PSUs), and purchases under the Company’s employee stock purchase plan (ESPP). The Company accounts for forfeitures as they occur for each type of award. Stock-based compensation expense related to restricted stock unit awards (RSUs) is based on the market value of the underlying stock on the date of grant and the related expense is recognized ratably over the requisite service period. The stock-based compensation expense related to performance share units (PSUs) is estimated at grant date based on the fair value of the award. The PSU awards are measured exclusively to the relative total shareholder return (TSR) performance, which is measured against the three-year TSR of a custom index of companies. The actual number of shares awarded is adjusted to between zero and 200% of the target award amount based upon achievement in each of the three
Research and Development Expense	Research and Development Expense Research and development (R&D) expenses include salaries, clinical trial costs, consultant fees, supplies, manufacturing costs for research and development programs, allocations of corporate costs, as well as post-marketing clinical studies. All such costs are charged to R&D expense as incurred. These expenses result from the Company’s independent R&D efforts as well as efforts associated with collaborations. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical costs are subject to revisions as trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the revision become known.
Advertising Costs	Advertising Costs
Restructuring	Restructuring Restructuring costs are included in Restructuring charges within the Consolidated Statements of Comprehensive Income. The Company has accounted for these costs in accordance with ASC 420, Exit or Disposal Cost Obligations (ASC 420) and ASC 712, Compensation - Nonretirement Postemployment Benefits
Income Taxes	Income Taxes The Company records the estimated future tax effects of temporary differences between the tax basis of assets and liabilities and amounts reported in its Consolidated Balance Sheets, as well as operating loss and tax credit carryforwards. The Company follows the guidelines set forth in the applicable accounting guidance regarding the recoverability of any tax assets recorded on the Consolidated Balance Sheets and provide any necessary allowances as required. Determining necessary allowances requires the Company to make assessments about the timing of future events, including the probability of expected future taxable income and available tax planning opportunities. When it is determined that it is more likely than not that some portion or all of the deferred tax assets will not be realized in the future, the deferred tax assets are reduced by a valuation allowance. The valuation allowance is sufficient to reduce the deferred tax assets to the amount determined is more likely than not to be realized. At this time, the Company has recorded a valuation allowance against its net deferred tax assets. The Company is subject to examination of its income tax returns by various tax authorities on a periodic basis. The Company regularly assesses the likelihood of adverse outcomes resulting from such examinations to determine the adequacy of its provision for income taxes. The Company has applied the provisions of the applicable accounting guidance on accounting for uncertainty in income taxes, which requires application of a more‑likely‑than‑not threshold to the recognition and de‑recognition of uncertain tax positions. If the recognition threshold is met, the applicable accounting guidance permits the Company to recognize a tax benefit measured at the largest amount of tax benefit that, in its judgment, is more than 50 percent likely to be realized upon settlement. It further requires that a change in judgment related to the expected ultimate resolution of uncertain tax positions be recognized in earnings in the period of such change. The Company recognizes tax liabilities in accordance with ASC Topic 740, Income Taxes , and adjusts these liabilities when its judgment changes as a result of the evaluation of new information not previously available. Due to the complexity of some of these uncertainties, the ultimate resolution may result in a payment that is materially different from our current estimate of the tax liabilities. These differences will be reflected as increases or decreases to income tax expense in the period in which they are determined.
Concentration of Risk	Concentration of RiskThe Company is subject to credit risk from its accounts receivable related to product sales.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13 Financial Instruments-Credit Losses (ASU 2016-13 or Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The Company adopted this standard on January 1, 2020 and updated its internal controls to include certain forward-looking considerations in the current process of developing and recognizing credit losses for in scope financial assets, which primarily included accounts receivable and a $3.5 million investment in a company engaged in medical research. ASC 326 had an immaterial impact to our allowance for credit losses reported in accounts receivable on our Condensed Consolidated Balance Sheet upon adoption. The investment is structured as a long-term loan receivable with a convertible feature and carried at amortized cost with accruing interest. To calculate the expected credit loss allowance, the Company utilized a probability-of-default method (PDM). This process estimates the probability of the loan being successfully paid back or converted into equity based on the ability of the investee to obtain FDA acceptance of its research. As of December 31, 2020, the Company estimated an expected credit loss of approximately $1.9 million, which was recognized in Other (expense) income in the Company’s Condensed Consolidated Statement of Comprehensive Income in the first quarter of 2020 and is included in Investments, net in the Company’s Condensed Consolidated Balance Sheet. The Company’s expected credit losses can vary from period to period based on several factors, such as progress of the medical research and FDA submission, and overall economic environment and the ability of the investee to fund its operations. The primary factor that contributed to the provision for expected credit losses as of the second quarter of 2020 was an evaluation of probability of default to exist based on the outlook of the macro environment due to the COVID-19 pandemic and its impact to delay the FDA acceptance process combined with the investee’s ability to fund its operations and raise capital if required. In June 2018, the FASB issued ASU 2018-18 Collaborative Arrangements (ASU 2018-18), which clarifies the interaction between ASC 808, Collaborative Arrangements (ASC 808) and ASC 606, Revenue from Contracts with Customers (ASC 606). The update clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer. In addition, the update precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue if the counterparty is not a customer for that transaction. The Company adopted the standard as of January 1, 2020 and have applied modified retrospective transition method to the date of initial application of ASC 606. The adoption of this guidance did not have a material impact on the Company’s condensed consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-15, Accounting for Cloud Computing Arrangements (Subtopic 350-40), which provides new guidance on the accounting for implementation, set-up, and other upfront costs incurred in a hosted cloud computing arrangement. Under the new guidance, entities will apply the same criteria for capitalizing implementation costs as they would for an internal-use software license arrangement. Effective January 1, 2020, the Company adopted the standard using the prospective approach to eligible costs incurred on or after the date of adoption. The adoption of this guidance did not have a material impact on the Company’s condensed consolidated financial statements. In August 2018, the FASB issued ASU 2018-13 Fair Value Measurement Disclosure Framework (ASU 2018-03), which is part of a broader disclosure framework project by the FASB to improve the effectiveness of disclosures by more clearly communicating the information to the user. The Company adopted the standard as of January 1, 2020 and included these disclosures in the condensed consolidated financial statements. The additional elements of this release did not impact the Company's condensed consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (ASU 2019-12): Simplifying the Accounting for Income Taxes

ORGANIZATION AND SUMMARY OF S_3

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of useful lives of property and equipment	Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets, as follows: Furniture and office equipment 3 - 5 years Machinery and equipment 5 - 7 years Laboratory equipment 3 - 5 years Leasehold improvements Shorter of estimated useful life or lease term
Schedule of sales and accounts receivable customer concentration risk	The three large, national wholesale distributors represent the vast majority of the Company’s business and represented the following percentage of consolidated revenue by customer and the percentage accounts receivable by customer related to product shipments for the years ended December 31, 2020 and 2019. Consolidated revenue Accounts receivable related to product sales 2020 2019 2020 2019 Cardinal Health 42 % 10 % 53 % 25 % McKesson Corporation 14 % 16 % 20 % 46 % AmerisourceBergen Corporation 13 % 12 % 18 % 17 % Collegium 11 % 52 % — % — % All others 20 % 10 % 9 % 12 % Total 100 % 100 % 100 % 100 %

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Schedule of Purchase Price and Corresponding Shares Issued	The following table reflects the acquisition date fair value of the consideration transferred with respect to the Zyla Merger: Total number of Company ordinary shares issued 25,478,539 Assertio share price as of May 20, 2020 $ 0.90 Fair value of common shares issued (in thousands) $ 22,931 Fair value of warrants and stock options issued (in thousands) (1) $ 11,626 Taxes paid by the Company on behalf of Zyla (in thousands) 529 Total purchase consideration (in thousands) $ 35,086
Schedule of Purchase Price Allocation	The following table reflects the initial preliminary and final fair values of the assets acquired and liabilities assumed, and measurement period adjustments during the year ended December 31, 2020, as of the acquisition date (in thousands): Initial Preliminary Purchase Price Allocation (PPA) to Fair Value Measurement period adjustments Final PPA to Fair Value Cash $ 7,585 $ — $ 7,585 Accounts receivable 23,133 — 23,133 Inventories 26,742 (12,481) 14,261 Property and equipment 4,512 (3,016) 1,496 Intangible assets 160,900 32,500 193,400 Other assets 9,629 (1,964) 7,665 Total identifiable assets acquired $ 232,501 $ 15,039 $ 247,540 Accounts payable 21,574 — 21,574 Accrued rebates, returns and discounts 33,254 — 33,254 Other accrued liabilities 15,434 8,424 23,858 Contingent consideration (a) 29,400 10,500 39,900 Debt (b) 111,900 (600) 111,300 Total liabilities assumed $ 211,562 $ 18,324 $ 229,886 Net identifiable assets acquired 20,939 (3,285) 17,654 Goodwill (c) 14,147 3,285 17,432 Net assets acquired 35,086 — $ 35,086 (a) Contingent consideration was recognized and measured at an estimated fair value as of the acquisition date. The contingent consideration liability assumed is the result of Zyla’s previous acquisition of INDOCIN Products. The liability assumed included contingent consideration related to royalties payable in the form of an earnout provision based on INDOCIN Product revenue estimates and a probability assessment with respect to the likelihood of achieving the level of net sales that would trigger the contingent payment. The fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement as defined in fair value measurement accounting. The key assumptions in determining the fair value are the discount rate and the probability assigned to the potential milestones being achieved. At each reporting date, the Company will subsequently re-measure the contingent consideration obligation to estimated fair value. Any changes in the fair value of contingent consideration will be recognized in operating expenses until the contingent consideration arrangement is settled. (b) The fair value of acquired debt is comprised of the following (in thousands): 13% Senior Secured Note due 2024 $ 95,000 Royalty rights obligation 3,300 Promissory note 3,000 Credit agreement 10,000 Total debt $ 111,300 Upon the Zyla Merger, the Company assumed and immediately paid off a $3.0 million promissory note. The promissory note was scheduled to mature on July 31, 2020. Additionally upon the Zyla Merger, the Company assumed and immediately paid off a $10.0 million credit agreement. The credit agreement was recognized by Zyla as a related party transaction as the lenders were also holders of a portion of the Zyla’s 13% Notes that were issued on January 31, 2019. The Credit Agreement was scheduled to mature on March 20, 2022. See Note 9, Debt , for further information regarding assumed Debt. (c) The Company recognized $17.4 million of goodwill which represents the fair value of assets net of the fair value of liabilities assumed in excess of consideration paid. Goodwill arising from the Zyla Merger is not expected to be deductible for tax purposes and is subject to material revision as the purchase price allocation is completed. The goodwill recognized is attributable primarily to expected synergies and the assembled workforce of Zyla.
Schedule of Pro Forma Financial Information	The following table reflects the pro forma consolidated total revenues and net loss for the periods presented, as if the acquisition of Zyla had occurred on January 1, 2019. Unaudited Twelve Months Ended December 31, 2020 2019 Total revenues $ 131,969 $ 246,375 Net loss $ (60,105) $ (145,418)

REVENUE (Tables)

REVENUE (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of disaggregated revenue from contracts with customers	The following table reflects summary revenues the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Product sales, net: INDOCIN Products (1) $ 31,684 $ — CAMBIA 28,350 32,453 Zipsor 13,286 12,498 SPRIX ( (1) 11,077 — Other (2) 9,101 63,855 Total product sales, net 93,498 108,806 Commercialization agreement revenue, net 11,258 118,614 Royalties and milestone revenue 1,519 2,084 Total revenues $ 106,275 $ 229,504 (1) Products acquired in connection with Zyla Merger represent product sales, net for the period of May 20, 2020 through December 31, 2020.
Summary of contract assets	The following table reflects changes in the Company’s contract asset as of December 31, 2020 (in thousands): Balance as of Balance as of December 31, 2019 Additions Deductions December 31, 2020 Contract assets: Contract asset - Collegium, net 1,896 — (1,896) — $ 1,896 $ — $ (1,896) $ —

ACCOUNTS RECEIVABLES, NET (Tabl

ACCOUNTS RECEIVABLES, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Summary of accounts receivables, net	The following table reflects accounts receivables, net, as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Receivables related to product sales, net $ 40,784 $ 38,353 Receivables from Collegium 3,566 4,104 Other — 287 Total Accounts receivable, net $ 44,350 $ 42,744

INVENTORIES, NET (Tables)

INVENTORIES, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of Inventories	The following table reflects the components of inventory, net as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Raw materials $ 1,136 $ 1,065 Work-in-process 1,340 426 Finished goods 9,236 1,921 Total Inventories, net $ 11,712 $ 3,412

PROPERTY AND EQUIPMENT, NET (Ta

PROPERTY AND EQUIPMENT, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	The following table reflects property and equipment as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Furniture and office equipment $ 2,680 $ 2,557 Machinery and equipment — 2,731 Laboratory equipment 20 221 Leasehold improvements 10,523 9,858 13,223 15,367 Less: Accumulated depreciation and amortization (10,786) (11,870) Property and equipment, net $ 2,437 $ 3,497

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of intangible assets	The following table reflects the gross carrying amounts and net book values of intangible assets as of December 31, 2020 and 2019 (in thousands): December 31, 2020 December 31, 2019 Product rights Remaining Gross Accumulated Net Book Gross Accumulated Impairment Net Book INDOCIN Products 11.4 $ 154,100 $ (7,812) $ 146,288 $ — $ — $ — $ — SPRIX 6.4 39,000 (3,389) 35,611 — — — — CAMBIA 3.0 51,360 (36,163) 15,197 51,360 (31,027) — 20,333 Zipsor 1.2 27,250 (24,381) 2,869 27,250 (22,044) 5,206 OXAYDO 0.4 300 (183) 117 — — — — NUCYNTA 0.0 — — — 1,019,978 (455,192) (189,790) 374,996 Total Intangible Assets $ 272,010 $ (71,928) $ 200,082 $ 1,098,588 $ (508,263) $ (189,790) $ 400,535
Summary of the future amortization expenses of intangible assets	The following table reflects expected future amortization expense related to the Company’s intangible assets (in thousands): Year Ending December 31, Estimated 2021 $ 26,004 2022 24,081 2023 23,337 2024 18,413 Thereafter 108,247 Total $ 200,082

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Accounts Payable and Accrued Liabilities, Current [Abstract]
Schedule of accounts payable and accrued liabilities	The following table reflects accrued liabilities as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Accrued compensation $ 5,498 $ 6,188 Accrued consent fees 4,500 — Accrued restructuring and one-time termination costs 8,744 3,763 Other accrued liabilities 12,829 8,997 Total accrued liabilities $ 31,571 $ 18,948

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Summary of debt	The following table reflects the Company’s debt as of December 31, 2020 and 2019 (in thousands): December 31, 2020 December 31, 2019 13% Senior Secured Note due 2024 (1) $ 80,250 $ — Royalty rights obligation (2) 3,533 — 2.50% Convertible Notes due 2021 335 145,000 5.00% Convertible Notes due 2024 (3) — 120,000 Senior Secured Notes (4) — 162,500 Total principal amount 84,118 427,500 Unamortized debt discounts (16) (70,699) Unamortized debt issuance costs — (5,543) Carrying value 84,102 351,258 Less: current portion of long-term debt (11,942) (80,000) Net, long-term debt $ 72,160 $ 271,258 (1) In connection with the Zyla Merger on May 20, 2020, the Company assumed the obligations of Zyla under its Existing Indenture, and Assertio and the other subsidiaries of the Company (other than Depo DR) became guarantors of Zyla's 13% Senior Secured Notes due 2024. (2) In connection with the Zyla Merger on May 20, 2020, the Company assumed the obligations of Zyla under its royalty rights agreement with each holder of its 13% Senior Secured Notes due 2024. (3) 2024 Notes settled and retired as of June 30, 2020. (4) During the year ended December 31, 2020, the Company repaid in full the outstanding aggregate principal amount of its Senior Secured Notes. The following is a summary of the carrying value of the Senior Notes as of December 31, 2019 (in thousands): 2019 Principal amount of the Senior Notes $ 162,500 Unamortized debt discount balance (4,035) Unamortized debt issuance costs (2,022) Total Senior Notes $ 156,443
Summary of interest expense	The following is a summary of Secured Notes interest expense for the year ended December 31, 2020 (in thousands): December 31, 2020 Stated coupon interest $ 6,870 Total interest expense $ 6,870 December 31, 2020 2019 Stated coupon interest $ 637 $ 6,708 Amortization of debt discount and debt issuance costs 1,550 15,398 Total interest expense 2021 Notes $ 2,187 $ 22,106 December 31, 2020 2019 Stated coupon interest $ 1,090 $ 2,250 Amortization of debt discount and debt issuance costs 1,273 2,583 Total interest expense 2024 Notes $ 2,363 $ 4,833 December 31, 2020 2019 Contractual interest expense $ 1,648 $ 25,559 Amortization of debt discount and debt issuance costs 2,699 5,783 Total interest expense $ 4,347 $ 31,342
Summary of the liability components	The following is a summary of the liability component of the 2021 Notes as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Principal amount of the 2021 Notes $ 335 $ 145,000 Unamortized discount of the liability component — (14,963) Unamortized debt issuance costs — (725) Total 2021 Notes $ 335 $ 129,312 December 31, 2019 Principal amount of the 2024 Notes $ 120,000 Unamortized discount of the liability component (51,701) Unamortized debt issuance costs (2,796) Total 2024 Notes $ 65,503

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Schedule of restructuring costs	The following table reflects total expenses related to restructuring activities recognized within the Consolidated Statement of Comprehensive Income as restructuring charges for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Employee compensation costs $ 15,705 $ 3,891 Other exit costs 2,101 — Total restructuring charges $ 17,806 $ 3,891
Schedule of accrued restructuring and severance costs	The following table reflects cash activity related to the Company’s accrued restructuring as of December 31, 2020 and 2019 (in thousands): Employee separation costs Other exit costs Total Balance as of December 31, 2018 $ 1,578 $ — $ 1,578 Accruals 3,891 $ — 3,891 Cash paid (1,706) — (1,706) Balance as of December 31, 2019 $ 3,763 $ — $ 3,763 Accruals 15,705 2,101 17,806 Adjustment to previous accrual estimate (594) — (594) Write off of fixed assets and leases and other adjustments — (1,888) (1,888) Cash paid (10,130) (213) (10,343) Balance as of December 31, 2020 $ 8,744 $ — $ 8,744

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of lease cost components, Cash Flow information, and term and discount rate information	The following table reflects lease expense for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Financial Statement Classification Operating lease cost Selling, general and administrative expenses $ 1,760 $ 718 Operating lease cost Other (loss) gain 1,391 591 Total lease cost $ 3,151 $ 1,309 Sublease Income Other (loss) gain $ 2,236 $ 1,386 The following table reflects supplemental cash flow information related to leases for the years ended December 31, 2020 and 2019 (in thousands): Year ended Year ended Cash paid for amounts included in measurement of liabilities: Operating cash flows from operating leases $ 3,004 $ 2,446 December 31, December 31, Weighted-average remaining lease term (years): Operating leases 2.2 3.2 Weighted-average discount rate: Operating leases 6.3 % 6.0 %
Schedule of supplemental Balance Sheet information	The following table reflects supplemental balance sheet information related to leases as of December 31, 2020 and 2019 (in thousands): Financial Statement Classification December 31, December 31, Assets Operating lease right-of-use assets Other long-term assets $ 2,347 $ 2,776 Liabilities Current operating lease liabilities Other current liabilities $ 2,683 $ 2,094 Noncurrent operating lease liabilities Other long term liabilities 2,815 4,820 Total lease liabilities $ 5,498 $ 6,914
Schedule of maturity of lease liabilities	The following table reflects future minimum lease payments under the Company’s non-cancelable operating leases as of December 31, 2020 (in thousands): Lease Payments 2021 2,917 2022 2,308 2023 632 Thereafter — Total lease payments $ 5,857 Less: Interest 359 Present value of lease liabilities $ 5,498

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of stock-based compensation expense	The following table reflects stock‑based compensation expense recognized in the Company’s Consolidated Statements of Comprehensive Income for the years ended December 31, 2020 and 2019 (in thousands): Years Ended December 31, 2020 2019 Cost of sales (excluding amortization of intangible assets) $ 92 $ 106 Research and development expenses 268 693 Selling, general and administrative expenses 9,565 9,797 Restructuring charges 999 — Total $ 10,924 $ 10,596
Schedule of assumptions used to calculate the fair value of option grants	The following table reflects assumptions used to calculate the fair value of option grants for the year ended December 31, 2020: 2020 Risk-free interest rate 0.20% - 0.35% Dividend yield —% Expected option term (in years) 3.4 - 5.0 Expected stock price volatility 80%
Schedule of assumptions used to calculate the fair value of stock purchase rights granted under the ESPP	The following table reflects assumptions used to calculate the fair value of stock purchase rights granted under the ESPP for the years ended December 31, 2020 and 2019: 2020 2019 Employee Stock Purchase Plan Risk-free interest rate 0.09% - 0.18% 1.63% - 2.35% Dividend yield —% —% Expected term (in years) 0.5 0.5 Expected stock price volatility 85.8% - 142.3% 57.2% - 132.2%
Summary of the options activity	The following tables reflects activity for the year ended December 31, 2020 under the 2004 Plan (dollar amounts in thousands): Shares Weighted- Weighted- Aggregate Options outstanding as of December 31, 2019 345,206 $ 7.29 Options granted — — Options exercised — — Options forfeited — — Options expired (221,706) 7.76 Options outstanding as of December 31, 2020 123,500 $ 6.43 1.9 $ — Options vested and expected as of vest at December 31, 2020 123,500 $ 6.43 1.9 $ — Options exercisable as of December 31, 2020 123,500 $ 6.43 1.9 $ — The following table reflects option activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted- Aggregate Options outstanding as of December 31, 2019 1,178,045 $ 12.64 Options granted 200,000 0.80 Options exercised — — Options forfeited (46,285) 9.17 Options expired (367,372) 13.68 Options outstanding as of December 31, 2020 964,388 $ 9.14 4.83 $ — Options vested and expected to vest as of December 31, 2020 964,388 $ 9.14 4.83 $ — Options exercisable as of December 31, 2020 716,501 $ 11.47 3.6 $ — The following table reflects option activity for the year ended December 31, 2020 under the 2019 Zyla Plan (dollar amounts in thousands): Shares Weighted Weighted- Aggregate Options outstanding as of December 31, 2019 — $ — Options granted 4,985,875 0.73 Options exercised — — Options forfeited (952,101) 0.70 Options expired (90,025) 1.12 Options outstanding as of December 31, 2020 3,943,749 0.73 9.3 — Options vested and expected to vest as of December 31, 2020 3,943,749 0.73 9.3 — Options exercisable as of December 31, 2020 1,933,604 0.80 9.5 —
Schedule of restricted stock units and performance-based restricted stock units activity	The following table reflects RSU activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted Non-vested performance-based restricted stock units as of December 31, 2019 2,936,715 $ 4.64 Granted 5,985,196 0.97 Vested (1,225,191) 4.77 Forfeited (2,199,758) 1.99 Non-vested restricted stock units as of December 31, 2020 5,496,962 $ 2.32 0.8 The following table reflects PSU activity for the year ended December 31, 2020 under the 2014 Amended Plan (dollar amounts in thousands): Number of Weighted Weighted Aggregate Non-vested performance-based restricted stock units as of December 31, 2019 983,843 $ 8.11 Granted — — Vested — — Forfeited (78,007) 6.74 Non-vested performance-based restricted stock units as of December 31, 2020 905,836 $ 8.23 0.68 $ 324

NET (LOSS) INCOME PER SHARE (Ta

NET (LOSS) INCOME PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of calculation of basic and diluted earnings per common share	The following table reflects the calculation of basic and diluted earnings per common share for the years ended December 31, 2020 and 2019 (in thousands, except for per share amounts): Year ended December 31, 2020 2019 Basic net income (loss) per share Net loss $ (28,144) $ (217,201) Weighted average common shares outstanding 104,835 70,716 Basic net loss per share $ (0.27) $ (3.07) Diluted net income (loss) per share Net loss $ (28,144) $ (217,201) Weighted average common shares outstanding 104,835 70,716 Add: effect of dilutive securities — — Denominator for diluted loss per share 104,835 70,716 Diluted net loss per share $ (0.27) $ (3.07)
Schedule of antidilutive securities excluded from computation of diluted net income (loss) per share	The following table reflects outstanding potentially dilutive shares of common stock that are not included in the computation of diluted net income (loss) per share because, to do so would be anti-dilutive for the years ended December 31, 2020, and 2019 (in thousands): Year ended December 31, 2020 2019 2.50% Convertible Notes due 2021 1,344 13,895 5.00% Convertible Notes due 2024 6,831 14,895 Stock options and equivalents 10,620 6,486 Total potentially dilutive common shares 18,795 35,276

FAIR VALUE (Tables)

FAIR VALUE (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of fair value hierarchy for financial assets and liabilities measured at fair value on a recurring basis	The following tables reflect the fair value hierarchy for Company financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019 (in thousands): December 31, 2020 Financial Statement Classification Level 1 Level 2 Level 3 Total Assets: Money market funds Cash and cash equivalents $ 77 $ — $ — $ 77 Total $ 77 $ — $ — $ 77 Liabilities: Short-term contingent consideration Contingent consideration liability $ — $ — $ 6,776 $ 6,776 Long-term contingent consideration Contingent consideration liability — — 31,776 31,776 Total $ — $ — $ 38,552 $ 38,552 December 31, 2019 Financial Statement Classification Level 1 Level 2 Level 3 Total Assets: Collegium warrants Investments $ — $ 9,629 $ — $ 9,629 Total $ — $ 9,629 $ — $ 9,629 Liabilities: Contingent consideration Contingent consideration liability $ — $ — $ 168 $ 168 Total $ — $ — $ 168 $ 168
Summary of the changes in fair value of all financial liabilities measured at fair value on a recurring basis using significant unobservable inputs	The following table summarizes changes in fair value that are measured on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2020, and 2019 (in thousands): December 31, 2020 2019 Fair value, beginning of the period $ 168 $ 1,038 Contingent consideration acquired with Zyla Merger 39,900 — Change in fair value of contingent consideration recorded within costs and expenses 1,500 (983) Cash payment related to contingent consideration (3,016) — Changes in fair value of contingent consideration recorded in interest expense — 113 Total $ 38,552 $ 168

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of loss before income taxes by source	The following table reflects Loss before income taxes by source for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 U.S. $ (45,327) $ (222,484) Outside the U.S. (186) — Net loss before income taxes $ (45,513) $ (222,484)
Schedule of (benefit from) provision for income taxes	The following table reflects benefit provision for income taxes for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Current: Federal $ (9,100) $ (1,231) State 155 1,715 Total current taxes $ (8,945) $ 484 Deferred: Federal $ (7,037) $ (5,767) State (1,387) — Total deferred taxes (8,424) (5,767) Total benefit for income taxes $ (17,369) $ (5,283)
Schedule of reconciliation of income taxes at the statutory federal income tax rate to the actual tax rate	The following table reflects a reconciliation of income taxes at the statutory federal income tax rate to the actual tax rate included in the Statements of Comprehensive Income for the years ended December 31, 2020 and 2019 (in thousands): Year ended December 31, 2020 2019 Tax at federal statutory rate $ (9,558) $ (46,722) State tax, net of federal benefit 276 (3,845) Goodwill impairment 3,661 — Disallowed officers' compensation 818 — Non-deductible transaction cost 451 — Non-deductible meals and entertainment 148 129 Stock based compensation 17 2,038 Change in valuation allowance (13,029) 48,943 Uncertain tax provisions (190) (5,758) Non-deductible other expense 37 5,837 Research credit — (138) Intraperiod tax allocations — (5,767) Total tax benefit $ (17,369) $ (5,283)
Schedule of significant components of the Company's deferred tax assets	The following table reflects significant components of the Company’s deferred tax assets are as of December 31, 2020 and 2019 (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating losses $ 81,471 $ 5,885 Tax credit carryforwards 3,360 1,411 Intangible assets — 82,582 Stock-based compensation 2,999 1,907 Operating lease liabilities 1,248 1,577 Fixed assets 1,315 — Reserves and other accruals not currently deductible 20,652 9,729 Disallowed interest carryforward 15,496 718 Total deferred tax assets $ 126,541 $ 103,809 Valuation allowance for deferred tax assets (103,906) (90,820) $ 22,635 $ 12,989 Deferred tax liabilities: Intangible assets $ (21,739) $ — Convertible debt (459) (12,247) Fixed Assets — (109) Operating lease right-of-use assets (437) (633) Net deferred tax liability $ — $ —
Summary of the activity related to the entity's unrecognized tax benefits	The following table reflects activity related to the Company’s unrecognized tax benefits for the years ended December 31, 2020 and 2019 (in thousands): Unrecognized tax benefits—December 31, 2018 $ 16,064 Increases related to current year tax positions 212 Changes in prior year tax positions (232) Decreases related to lapse of statutes (12,011) Unrecognized tax benefits—December 31, 2019 $ 4,033 Increases related to current year tax positions 194 Changes in prior year tax positions (2) Decreases related to lapse of statutes (124) Unrecognized tax benefits—December 31, 2020 $ 4,101

ORGANIZATION AND SUMMARY OF S_4

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Organization (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 03, 2020	Feb. 13, 2020	Jan. 10, 2020	Dec. 31, 2020	May 20, 2020	May 19, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Par value (in dollars per share)				$ 0.0001			$ 0.0001
Disposal Group, Disposed of by Sale, Not Discontinued Operations | NUCYNTA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses		$ 375
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gralise
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses	$ 38.8		$ 75
Consideration received			$ 130.3
Consideration receivable as percentage of net sales after closing			75.00%
Threshold for consideration receivable on net sales after closing			$ 70
Remaining consideration receivable balance	39.7
Remaining consideration receivable reduction	$ 0.9
Zyla Life Sciences
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Par value (in dollars per share)					$ 0.0001
Zyla Life Sciences | Assertio Therapeutics
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Par value (in dollars per share)						$ 0.0001

ORGANIZATION AND SUMMARY OF S_5

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment Information (Details)	12 Months Ended
	Dec. 31, 2020segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	1

ORGANIZATION AND SUMMARY OF S_6

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment, Long-Lived Assets and Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	May 20, 2020
Property, Plant and Equipment [Line Items]
Market capitalization	$ 38,000	$ 72,000
Zyla Life Sciences
Property, Plant and Equipment [Line Items]
Goodwill	$ 17,432		$ 14,147
Minimum | Furniture and office equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Minimum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Minimum | Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum | Furniture and office equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Maximum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	7 years
Maximum | Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years

ORGANIZATION AND SUMMARY OF S_7

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details)	12 Months Ended
	Dec. 31, 2020
Product Sales and Royalties
Product return period prior to expiration	6 months
Period after expiration for accepting unsalable product	12 months
Cash discount (as a percent)	2.00%
Discount reimbursement period after filling of prescription subject to discount	1 month
Minimum
Product Sales and Royalties
Receivables, collection period	1 month
Product shelf-life	24 months
Discount taken off period after the quarter in which product shipped to the customer	1 month
Period after the quarter in which prescription is filled for paying rebate	2 months
Managed care rebate, period after quarter in which prescription is filled	1 month
Medicare Part D coverage gap rebate, period after quarter in which prescription is filled	2 months
Maximum
Product Sales and Royalties
Receivables, collection period	2 months
Product return period prior to expiration	6 months
Period after expiration for accepting unsalable product	12 months
Product shelf-life	48 months
Discount taken off period after the quarter in which product shipped to the customer	2 months
Period after the quarter in which prescription is filled for paying rebate	3 months
Managed care rebate, period after quarter in which prescription is filled	3 months
Medicare Part D coverage gap rebate, period after quarter in which prescription is filled	3 months

ORGANIZATION AND SUMMARY OF S_8

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Leases (Details)	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent

ORGANIZATION AND SUMMARY OF S_9

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Advertising Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Advertising expense	$ 0.4	$ 0.8

ORGANIZATION AND SUMMARY OF _10

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Risk (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)
Concentration Risk [Line Items]
Accounts receivable related to product sales | $	$ 40.8	$ 38.4
Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Number of major distributors | item	3

ORGANIZATION AND SUMMARY OF _11

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Product Shipments and Accounts Receivable, By Distributor (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	100.00%	100.00%
Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	100.00%	100.00%
Cardinal Health | Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	42.00%	10.00%
Cardinal Health | Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	53.00%	25.00%
McKesson Corporation | Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	14.00%	16.00%
McKesson Corporation | Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	20.00%	46.00%
AmerisourceBergen Corporation | Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	13.00%	12.00%
AmerisourceBergen Corporation | Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	18.00%	17.00%
Collegium | Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	11.00%	52.00%
Collegium | Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	0.00%	0.00%
All others | Customer concentration risk | Consolidated revenue
Concentration Risk [Line Items]
Total	20.00%	10.00%
All others | Credit concentration risk | Accounts receivable related to product sales
Concentration Risk [Line Items]
Total	9.00%	12.00%

ORGANIZATION AND SUMMARY OF _12

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Jan. 01, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investment, long-term loan receivable			$ 3,500
Investment, long-term receivable, credit loss expense	$ 1,900
Convertible debt
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reacquisition of equity component		$ 19,532
Convertible debt | Additional Paid-In Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reacquisition of equity component		$ 19,532

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions	May 20, 2020USD ($)$ / sharesshares	Jun. 30, 2020USD ($)	Dec. 31, 2020segment	Dec. 31, 2019USD ($)
Business Acquisition [Line Items]
Number of operating segments | segment			1
Stock Options
Business Acquisition [Line Items]
Vesting period			4 years
Zyla Life Sciences
Business Acquisition [Line Items]
Merger exchange ratio	2.5
Business transaction costs associated with merger		$ 6.6
Proforma information adjustment, excluded income from Zyla's January 2019 Reorganization				$ 115.2
Proforma information adjustment, excluded loss from impairment of intangible assets				$ 189.8
Zyla Life Sciences | The 2019 Zyla Plan
Business Acquisition [Line Items]
Issued (in shares) | shares	5
Issued, average fair market value, per share (in dollars per share) | $ / shares	$ 0.62
Issued, value recognized as merger consideration	$ 0.4
Zyla Life Sciences | Iroko | Warrant Agreements
Business Acquisition [Line Items]
Exercise aggregate ownership percentage maximum threshold	49.00%
Exercise aggregate ownership percentage term	18 months
Zyla Life Sciences | Stock Options | The 2019 Zyla Plan
Business Acquisition [Line Items]
Term of awards (may not exceed)	10 years
Vesting period	3 years
Vesting percentage	33.00%

ACQUISITIONS - Acquisition Date

ACQUISITIONS - Acquisition Date Fair Value of Consideration Transferred (Details) $ / shares in Units, $ in Thousands	May 20, 2020USD ($)$ / sharesshares
Business Acquisition [Line Items]
Share price (in dollars per share) | $ / shares	$ 0.90
Zyla Life Sciences
Business Acquisition [Line Items]
Total number of Company ordinary shares issued (in shares) | shares	25,478,539
Assertio share price as of May 20, 2020 (in dollars per share) | $ / shares	$ 0.90
Taxes paid by the Company on behalf of Zyla (in thousands)	$ 529
Total purchase consideration (in thousands)	35,086
Zyla Life Sciences | Common Stock
Business Acquisition [Line Items]
Fair value issued (in thousands)	22,931
Zyla Life Sciences | Warrants and Options
Business Acquisition [Line Items]
Fair value issued (in thousands)	$ 11,626
Zyla Life Sciences | Warrants
Business Acquisition [Line Items]
Purchase price, number of shares outstanding (in shares) | shares	12,430,913
Zyla Life Sciences | Warrants | Zyla Life Sciences
Business Acquisition [Line Items]
Purchase price, number of shares outstanding (in shares) | shares	4,972,365
Purchase price, number of shares outstanding, per share (in dollars per share) | $ / shares	$ 0.0004

ACQUISITIONS - Purchase Price A

ACQUISITIONS - Purchase Price Allocation (Details) - USD ($) $ in Thousands	7 Months Ended
	Dec. 31, 2020	May 20, 2020	Jan. 31, 2019
13% Senior Secured Note due 2024 | Senior Notes
Adjustments to Purchase Price Allocation to Fair Value
Interest rate	13.00%	13.00%
13% Senior Secured Note due 2024 | Senior Notes | Zyla Life Sciences
Adjustments to Purchase Price Allocation to Fair Value
Interest rate			13.00%
Zyla Life Sciences
Purchase Price Allocation to Fair Value
Cash	$ 7,585	$ 7,585
Accounts receivable	23,133	23,133
Inventories	14,261	26,742
Property and equipment	1,496	4,512
Intangible assets	193,400	160,900
Other assets	7,665	9,629
Total identifiable assets acquired	247,540	232,501
Accounts payable	21,574	21,574
Accrued rebates, returns and discounts	33,254	33,254
Other accrued liabilities	23,858	15,434
Contingent consideration	39,900	29,400
Debt	111,300	111,900
Total liabilities assumed	229,886	211,562
Net identifiable assets acquired	17,654	20,939
Goodwill	17,432	14,147
Net assets acquired	35,086	$ 35,086
Adjustments to Purchase Price Allocation to Fair Value
Inventories	(12,481)
Property and equipment	(3,016)
Intangible assets	32,500
Other assets	(1,964)
Total identifiable assets acquired	15,039
Other accrued liabilities	8,424
Contingent consideration	10,500
Debt	(600)
Total liabilities assumed	18,324
Net identifiable assets acquired	(3,285)
Goodwill	3,285
Zyla Life Sciences | Promissory note
Purchase Price Allocation to Fair Value
Debt	3,000
Zyla Life Sciences | Credit agreement
Purchase Price Allocation to Fair Value
Debt	10,000
Zyla Life Sciences | 13% Senior Secured Note due 2024 | Senior Notes
Purchase Price Allocation to Fair Value
Debt	95,000
Zyla Life Sciences | Royalty rights obligation | Senior Notes
Purchase Price Allocation to Fair Value
Debt	$ 3,300

ACQUISITIONS - Pro Forma Financ

ACQUISITIONS - Pro Forma Financial Information (Details) - Zyla Life Sciences - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Total revenues	$ 131,969	$ 246,375
Net loss	$ (60,105)	$ (145,418)

REVENUE - Schedule of Disaggreg

REVENUE - Schedule of Disaggregated Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 106,275	$ 229,504
Product sales, net
Disaggregation of Revenue [Line Items]
Total revenues	93,498	108,806
INDOCIN Products
Disaggregation of Revenue [Line Items]
Total revenues	31,684	0
CAMBIA
Disaggregation of Revenue [Line Items]
Total revenues	28,350	32,453
Zipsor
Disaggregation of Revenue [Line Items]
Total revenues	13,286	12,498
SPRIX
Disaggregation of Revenue [Line Items]
Total revenues	11,077	0
Other
Disaggregation of Revenue [Line Items]
Total revenues	9,101	63,855
Commercialization agreement revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	11,258	118,614
Royalties and milestone revenue
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,519	$ 2,084

REVENUE - Product Sales (Detail

REVENUE - Product Sales (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues		$ 106,275	$ 229,504
CAMBIA
Disaggregation of Revenue [Line Items]
Total revenues		28,350	32,453
Zipsor
Disaggregation of Revenue [Line Items]
Total revenues		13,286	12,498
Gralise
Disaggregation of Revenue [Line Items]
Total revenues		$ 300	$ 63,100
Zyla Life Sciences
Disaggregation of Revenue [Line Items]
Product sales from acquiree	$ 7,700

REVENUE - Commercialization Agr

REVENUE - Commercialization Agreement Revenue, Net (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Collaboration and License Agreements
Total revenues		$ 106,275	$ 229,504
Contract Assets
Contract asset, beginning balance		1,896
Additions		0
Deductions		(1,896)
Contract asset, ending balance		0	1,896
Collegium
Contract Assets
Contract asset, beginning balance		1,896
Additions		0
Deductions		(1,896)
Contract asset, ending balance		0	1,896
Contract liability	$ 10,000
Collegium warrants	$ 8,800
Royalties and milestones
Collaboration and License Agreements
Total revenues		1,519	2,084
Commercialization agreement, net
Collaboration and License Agreements
Total revenues		11,258	$ 118,614
Amended Commercialization Agreement | Collegium
Collaboration and License Agreements
Total revenues		11,300
Contract asset, amortization		1,800
Amended Commercialization Agreement | Royalties and milestones | Collegium
Collaboration and License Agreements
Total revenues		$ 13,100

REVENUE - Royalties and Milesto

REVENUE - Royalties and Milestone Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CAMBIA | Canada
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	$ 1.5	$ 2.1

ACCOUNTS RECEIVABLES, NET - Sch

ACCOUNTS RECEIVABLES, NET - Schedule of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivables
Total Accounts receivable, net	$ 44,350	$ 42,744
Receivables related to product sales, net
Accounts receivables
Total Accounts receivable, net	40,784	38,353
Receivables from Collegium
Accounts receivables
Total Accounts receivable, net	3,566	4,104
Other
Accounts receivables
Total Accounts receivable, net	$ 0	$ 287

ACCOUNTS RECEIVABLES, NET - Nar

ACCOUNTS RECEIVABLES, NET - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Allowance for cash discounts for prompt payment	$ 1.3	$ 1.2

INVENTORIES, NET - Schedule of

INVENTORIES, NET - Schedule of Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory
Raw materials	$ 1,136	$ 1,065
Work-in-process	1,340	426
Finished goods	9,236	1,921
Total Inventories, net	$ 11,712	$ 3,412

INVENTORIES, NET - Narrative (D

INVENTORIES, NET - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory reserves	$ 2.3	$ 0.4

PROPERTY AND EQUIPMENT, NET - S

PROPERTY AND EQUIPMENT, NET - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 13,223	$ 15,367
Less: Accumulated depreciation and amortization	(10,786)	(11,870)
Property and equipment, net	2,437	3,497
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,680	2,557
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	0	2,731
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	20	221
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 10,523	$ 9,858

PROPERTY AND EQUIPMENT, NET - N

PROPERTY AND EQUIPMENT, NET - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation expense			$ 1,600	$ 1,200
Loss on disposal	$ 900	$ 10,100	$ 1,588	$ 10,076
Property plant and equipment disposals		9,600
Disposal costs		$ 500

INTANGIBLE ASSETS AND GOODWIL_2

INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 272,010	$ 1,098,588
Accumulated Amortization	(71,928)	(508,263)
Impairment		(189,790)
Total	$ 200,082	400,535
Product rights | INDOCIN Products
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	11 years 4 months 24 days
Gross Carrying Amount	$ 154,100	0
Accumulated Amortization	(7,812)	0
Total	$ 146,288	0
Product rights | SPRIX
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	6 years 4 months 24 days
Gross Carrying Amount	$ 39,000	0
Accumulated Amortization	(3,389)	0
Total	$ 35,611	0
Product rights | CAMBIA
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	3 years
Gross Carrying Amount	$ 51,360	51,360
Accumulated Amortization	(36,163)	(31,027)
Total	$ 15,197	20,333
Product rights | Zipsor
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	1 year 2 months 12 days
Gross Carrying Amount	$ 27,250	27,250
Accumulated Amortization	(24,381)	(22,044)
Total	$ 2,869	5,206
Product rights | OXAYDO
Finite-Lived Intangible Assets [Line Items]
Remaining Useful Life (In years)	4 months 24 days
Gross Carrying Amount	$ 300	0
Accumulated Amortization	(183)	0
Total	117	0
Product rights | NUCYNTA
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	0	1,019,978
Accumulated Amortization	0	(455,192)
Impairment		(189,790)
Total	$ 0	$ 374,996	$ 564,800

INTANGIBLE ASSETS AND GOODWIL_3

INTANGIBLE ASSETS AND GOODWILL - Schedule of Future Amortization Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 26,004
2022	24,081
2023	23,337
2024	18,413
Thereafter	108,247
Total	$ 200,082	$ 400,535

INTANGIBLE ASSETS AND GOODWIL_4

INTANGIBLE ASSETS AND GOODWILL - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020	May 20, 2020	Dec. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 24,783	$ 101,774
Intangible assets carrying value	200,082	400,535
Market capitalization	38,000		$ 72,000
Zyla Life Sciences
Finite-Lived Intangible Assets [Line Items]
Goodwill	17,432			$ 14,147
INDOCIN Products | Zyla Life Sciences
Finite-Lived Intangible Assets [Line Items]
Intangible assets fair value				154,100
SPRIX | Zyla Life Sciences
Finite-Lived Intangible Assets [Line Items]
Intangible assets fair value				39,000
OXAYDO | Zyla Life Sciences
Finite-Lived Intangible Assets [Line Items]
Intangible assets fair value				$ 300
Product rights | INDOCIN Products
Finite-Lived Intangible Assets [Line Items]
Intangible assets carrying value	146,288	0
Product rights | SPRIX
Finite-Lived Intangible Assets [Line Items]
Intangible assets carrying value	35,611	0
Product rights | OXAYDO
Finite-Lived Intangible Assets [Line Items]
Intangible assets carrying value	117	0
Product rights | NUCYNTA
Finite-Lived Intangible Assets [Line Items]
Intangible assets impairment loss		189,800
Intangible assets carrying value	$ 0	$ 374,996			$ 564,800

ACCRUED LIABILITIES - Schedule

ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued compensation	$ 5,498	$ 6,188
Accrued consent fees	4,500	0
Accrued restructuring and one-time termination costs	8,744	3,763	$ 1,578
Other accrued liabilities	12,829	8,997
Total accrued liabilities	$ 31,571	$ 18,948

DEBT - Summary of Debt (Details

DEBT - Summary of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	May 20, 2020	Dec. 31, 2019	Aug. 13, 2019	Sep. 09, 2014
Debt Instrument [Line Items]
Total principal amount	$ 84,118		$ 427,500
Unamortized debt discounts	(16)		(70,699)
Unamortized debt issuance costs	0		(5,543)
Carrying value	84,102		351,258
Less: current portion of long-term debt	(11,942)		(80,000)
Long-term debt	72,160		271,258
Senior Notes
Debt Instrument [Line Items]
Total principal amount	$ 0		162,500
Unamortized debt discounts			(4,035)
Unamortized debt issuance costs			(2,022)
Carrying value			156,443
Senior Notes | 13% Senior Secured Note due 2024
Debt Instrument [Line Items]
Interest rate	13.00%	13.00%
Total principal amount	$ 80,250		0
Senior Notes | Royalty rights obligation
Debt Instrument [Line Items]
Total principal amount	$ 3,533		0
Convertible debt | 2.50% Convertible Notes due 2021
Debt Instrument [Line Items]
Interest rate	2.50%				2.50%
Total principal amount	$ 335		145,000
Unamortized debt discounts	0		(14,963)		$ (119,000)
Unamortized debt issuance costs	0		(725)
Carrying value	$ 335		129,312
Convertible debt | 5.0% Convertible Notes debt 2024
Debt Instrument [Line Items]
Interest rate	5.00%			5.00%
Total principal amount	$ 0		120,000
Unamortized debt discounts			(51,701)	$ (54,200)
Unamortized debt issuance costs			(2,796)
Carrying value			$ 65,503

DEBT - 13% Senior Secured Notes

DEBT - 13% Senior Secured Notes due 2024 (Details)	Jul. 31, 2020USD ($)	May 20, 2020USD ($)numberOfSeries	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 02, 2015USD ($)
Debt Instrument [Line Items]
Interest Expense, Debt			$ 6,870,000
Senior Notes
Debt Instrument [Line Items]
Par value of debt					$ 575,000,000
Interest Expense, Debt			$ 4,347,000	$ 31,342,000
13% Senior Secured Note due 2024 | Senior Notes
Debt Instrument [Line Items]
Interest rate		13.00%	13.00%
Par value of debt		$ 95,000,000
Number of series | numberOfSeries		2
Amortization payments percent		10.00%
Minimum liquidity ratio		9.5
Minimum liquidity		$ 7,500,000
Redemption of debt	$ 10,000,000
13% Senior Secured Note due 2024 | Senior Notes | Period One
Debt Instrument [Line Items]
Redemption price, percentage		100.00%
13% Senior Secured Note due 2024 | Senior Notes | Period Two
Debt Instrument [Line Items]
Redemption price, percentage		100.00%
Senior Secured Notes Due 2024, Series A-1 | Senior Notes
Debt Instrument [Line Items]
Par value of debt		$ 50,000,000
Senior Secured Notes Due 2024, Series A-2 | Senior Notes
Debt Instrument [Line Items]
Par value of debt		$ 45,000,000

DEBT - Royalty Rights Obligatio

DEBT - Royalty Rights Obligation (Details) - USD ($) $ in Thousands	May 20, 2020	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Interest expense		$ 6,870
Senior Notes
Debt Instrument [Line Items]
Interest expense		4,347	$ 31,342
Royalty rights obligation | Senior Notes
Debt Instrument [Line Items]
Royalty percentage	1.50%
Accrued royalties		3,500
Interest expense		200
Royalty rights obligation | Senior Notes | Royalty, Current
Debt Instrument [Line Items]
Accrued royalties		2,100
Royalty rights obligation | Senior Notes | Royalty, Noncurrent
Debt Instrument [Line Items]
Accrued royalties		$ 1,400

DEBT - 2.50% Convertible Senior

DEBT - 2.50% Convertible Senior Notes Due 2021 (Details) $ / shares in Units, shares in Thousands	Aug. 13, 2019USD ($)trading_day$ / sharesshares	Sep. 09, 2014USD ($)trading_day$ / shares	Apr. 30, 2020USD ($)	Feb. 29, 2020USD ($)	Dec. 31, 2020USD ($)$ / shares	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)shares	Apr. 08, 2020USD ($)	Feb. 19, 2020USD ($)
Debt Instrument [Line Items]
Debt instrument, unamortized discount					$ 16,000			$ 16,000	$ 70,699,000
Payment of a prepayment fee								264,731,000	30,000,000
(Loss) Gain on debt extinguishment								(56,113,000)	26,385,000
Amortization of debt discount and debt issuance costs								5,680,000	23,764,000
Liability Component [Abstract]
Total principal amount					84,118,000			84,118,000	427,500,000
Unamortized discount of the liability component					(16,000)			(16,000)	(70,699,000)
Unamortized debt issuance costs					0			0	(5,543,000)
Carrying value					$ 84,102,000			84,102,000	351,258,000
Interest Expense [Abstract]
Amortization of debt discount and debt issuance costs								5,680,000	$ 23,764,000
Interest expense								6,870,000
Common Stock
Debt Instrument [Line Items]
Issuance of common stock in conjunction with the Convertible Note Exchange (in shares) | shares	15,800								15,817
Common Stock | Beneficial Owner
Debt Instrument [Line Items]
Issuance of common stock in conjunction with the Convertible Note Exchange (in shares) | shares	1,700
Convertible debt
Debt Instrument [Line Items]
(Loss) Gain on debt extinguishment								(47,880,000)	$ 26,385,000
Amortization of debt discount and debt issuance costs								1,550,000	15,398,000
Reacquisition of equity component								19,532,000
Interest Expense [Abstract]
Stated coupon interest								637,000	6,708,000
Amortization of debt discount and debt issuance costs								1,550,000	15,398,000
Interest expense								2,187,000	22,106,000
Convertible debt | Additional Paid-In Capital
Debt Instrument [Line Items]
Reacquisition of equity component								$ 19,532,000
Convertible Senior Notes, 2.5% | Convertible debt
Debt Instrument [Line Items]
Interest rate		2.50%			2.50%			2.50%
Par value of debt	$ 145,000,000	$ 345,000,000			$ 300,000			$ 300,000
Net proceeds from debt offering		334,200,000
Underwriting discount		10,400,000
Offering expenses		$ 400,000
Trading days, number (trading day) | trading_day		20
Consecutive trading days, period (trading day) | trading_day		30
Stock price trigger (in dollars per share) | $ / shares		$ 25.01
Stock price trigger		130.00%			130.00%
Conversion price (in dollars per share) | $ / shares		$ 19.24			$ 19.24			$ 19.24
Consecutive trading-day period		5 days
Maximum product of the closing sale price of shares of the Company's common stock and the applicable conversion rate for such trading day (less than)		98.00%
Conversion rate of common stock		0.0519852
Effective interest rate		9.34%
Liability component of debt		$ 226,000,000
Debt instrument, unamortized discount		119,000,000			$ 0			$ 0	14,963,000
Equity component of debt	112,800,000	73,300,000
Amount of debt prepaid	200,000,000
Extinguishment of debt, cash paid	30,000,000
(Loss) Gain on debt extinguishment			$ (3,900,000)	$ (10,300,000)					26,400,000
Equity component									6,200,000
Amortization of debt discount and debt issuance costs	26,100,000
Unamortized balances of debt discount and debt issuance costs	18,900,000
Decrease in carrying amount of equity component	6,200,000
Repurchased aggregate principal amount			$ 42,100,000	$ 102,500,000
Reacquisition of equity component								300,000	4,763,000
Liability Component [Abstract]
Total principal amount					335,000			335,000	145,000,000
Unamortized discount of the liability component		(119,000,000)			0			0	(14,963,000)
Unamortized debt issuance costs					0			0	(725,000)
Carrying value					$ 335,000			$ 335,000	129,312,000
Interest Expense [Abstract]
Amortization of debt discount and debt issuance costs	26,100,000
Convertible Senior Notes, 2.5% | Convertible debt | Beneficial Owner
Debt Instrument [Line Items]
Par value of debt	22,000,000
Payment of a prepayment fee	$ 3,500,000
Convertible Senior Notes, 2.5% | Convertible debt | Additional Paid-In Capital
Debt Instrument [Line Items]
Equity issuance costs		$ 3,700,000
Reacquisition of equity component									4,763,000
Convertible Senior Notes, 5.0% | Convertible debt
Debt Instrument [Line Items]
Interest rate	5.00%				5.00%			5.00%
Par value of debt	$ 120,000,000
Trading days, number (trading day) | trading_day	20
Consecutive trading days, period (trading day) | trading_day	30
Stock price trigger	150.00%
Conversion price (in dollars per share) | $ / shares	$ 3.09
Conversion rate of common stock	0.3235198
Effective interest rate	17.82%
Liability component of debt	$ 65,800,000
Debt instrument, unamortized discount	54,200,000								51,701,000
Equity component of debt	32,600,000
(Loss) Gain on debt extinguishment						$ (12,400,000)	$ (21,300,000)
Equity component									23,999,000
Amortization of debt discount and debt issuance costs								$ 1,273,000	2,583,000
Repurchased aggregate principal amount										$ 34,500,000	$ 85,500,000
Reacquisition of equity component						$ 2,700,000	$ 16,800,000
Liability Component [Abstract]
Total principal amount					$ 0			0	120,000,000
Unamortized discount of the liability component	(54,200,000)								(51,701,000)
Unamortized debt issuance costs									(2,796,000)
Carrying value									65,503,000
Interest Expense [Abstract]
Stated coupon interest								1,090,000	2,250,000
Amortization of debt discount and debt issuance costs								1,273,000	2,583,000
Interest expense								$ 2,363,000	4,833,000
Convertible Senior Notes, 5.0% | Convertible debt | Beneficial Owner
Debt Instrument [Line Items]
Par value of debt	$ 13,200,000
Convertible Senior Notes, 5.0% | Convertible debt | Additional Paid-In Capital
Debt Instrument [Line Items]
Equity component									$ 23,999,000

DEBT - 5.00% Convertible Senior

DEBT - 5.00% Convertible Senior Notes Due 2024 (Details)	Apr. 08, 2020USD ($)	Aug. 13, 2019USD ($)trading_day$ / shares	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Feb. 19, 2020USD ($)
Debt Instrument [Line Items]
Debt instrument, unamortized discount					$ 16,000	$ 70,699,000
(Loss) Gain on debt extinguishment					(56,113,000)	26,385,000
Liability Component [Abstract]
Total principal amount					84,118,000	427,500,000
Unamortized discount of the liability component					(16,000)	(70,699,000)
Unamortized debt issuance costs					0	(5,543,000)
Carrying value					84,102,000	351,258,000
Interest Expense [Abstract]
Amortization of debt discount and debt issuance costs					5,680,000	23,764,000
Interest expense					6,870,000
Convertible debt
Debt Instrument [Line Items]
(Loss) Gain on debt extinguishment					(47,880,000)	26,385,000
Reacquisition of equity component					19,532,000
Interest Expense [Abstract]
Stated coupon interest					637,000	6,708,000
Amortization of debt discount and debt issuance costs					1,550,000	15,398,000
Interest expense					$ 2,187,000	22,106,000
Convertible Senior Notes, 5.0% | Convertible debt
Debt Instrument [Line Items]
Interest rate		5.00%			5.00%
Par value of debt		$ 120,000,000
Conversion rate of common stock		0.3235198
Conversion price (in dollars per share) | $ / shares		$ 3.09
Observation period		40 days
Stock price trigger		150.00%
Trading days, number (trading day) | trading_day		20
Consecutive trading days, period (trading day) | trading_day		30
Redemption price, percentage	99.50%	100.00%
Debt instrument, debt default, percent of principal and unpaid interest due and payable immediately		100.00%
Effective interest rate		17.82%
Estimated fair value of debt		$ 98,400,000
Liability component of debt		65,800,000
Debt instrument, unamortized discount		54,200,000				51,701,000
Debt instrument, unamortized discount, fair value		21,600,000
Equity component of debt		32,600,000
Debt and equity issuance costs, net		4,300,000
Debt issuance costs, net		2,900,000
Repurchased aggregate principal amount	$ 34,500,000						$ 85,500,000
(Loss) Gain on debt extinguishment			$ (12,400,000)	$ (21,300,000)
Reacquisition of equity component			$ 2,700,000	$ 16,800,000
Liability Component [Abstract]
Total principal amount					$ 0	120,000,000
Unamortized discount of the liability component		$ (54,200,000)				(51,701,000)
Unamortized debt issuance costs						(2,796,000)
Carrying value						65,503,000
Interest Expense [Abstract]
Stated coupon interest					1,090,000	2,250,000
Amortization of debt discount and debt issuance costs					1,273,000	2,583,000
Interest expense					$ 2,363,000	$ 4,833,000

DEBT - Senior Secured Notes (De

DEBT - Senior Secured Notes (Details) - USD ($)	Apr. 02, 2015	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost		$ 264,731,000	$ 30,000,000
(Loss) Gain on debt extinguishment		(56,113,000)	26,385,000
Carrying Value [Abstract]
Total principal amount		84,118,000	427,500,000
Unamortized discount of the liability component		(16,000)	(70,699,000)
Unamortized debt issuance costs		0	(5,543,000)
Carrying value		84,102,000	351,258,000
Interest Expense [Abstract]
Amortization of debt discount and debt issuance costs		5,680,000	23,764,000
Interest expense		6,870,000
Senior Notes
Debt Instrument [Line Items]
Par value of debt	$ 575,000,000
Proceeds from the issuance of debt	$ 562,000,000
Repurchased aggregate principal amount		162,500,000
Payment for Debt Extinguishment or Debt Prepayment Cost		4,900,000
Payment debt exit fees		4,400,000
(Loss) Gain on debt extinguishment		(8,233,000)	0
Write off of unamortized debt discount and debt issuance costs		3,300,000
Carrying Value [Abstract]
Total principal amount		0	162,500,000
Unamortized discount of the liability component			(4,035,000)
Unamortized debt issuance costs			(2,022,000)
Carrying value			156,443,000
Interest Expense [Abstract]
Stated coupon interest		1,648,000	25,559,000
Amortization of debt discount and debt issuance costs		2,699,000	5,783,000
Interest expense		$ 4,347,000	$ 31,342,000
Senior Notes | Three month LIBOR
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	9.75%
Interest rate through third anniversary	11.95%
Interest rate after third anniversary	12.95%
Senior Notes | Three month LIBOR | Minimum
Debt Instrument [Line Items]
Interest rate	1.00%
Senior Notes | NUCYNTA
Debt Instrument [Line Items]
Proceeds from the issuance of debt	$ 550,000,000

RESTRUCTURING CHARGES - Narrati

RESTRUCTURING CHARGES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		$ 15,705	$ 3,891
Other exit costs		2,101	0
Restructuring liability		8,744	3,763	$ 1,578
December 2020 Plan
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		9,600
Other exit costs		1,600
Restructuring liability		7,200
Zyla Merger Reorganization
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		5,600
Other exit costs		200
Severance costs, share-based compensation		1,000
Restructuring liability		700
Reduction In Workforce Due To COVID-19
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs	$ 300
Other exit costs	$ 300
2019 Plan
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		200	3,900
Restructuring liability		$ 800	$ 3,800

RESTRUCTURING CHARGES - Schedul

RESTRUCTURING CHARGES - Schedule of Restructuring Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Restructuring costs
Employee compensation costs	$ 15,705	$ 3,891
Other exit costs	2,101	0
Total restructuring charges	$ 17,806	$ 3,891

RESTRUCTURING CHARGES - Sched_2

RESTRUCTURING CHARGES - Schedule of Accrued Restructuring and Severance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accrued restructuring and severance costs rollforward
Balance at beginning of period	$ 3,763	$ 1,578
Accruals	17,806	3,891
Adjustment to previous accrual estimate	(594)
Write off of fixed assets and leases and other adjustments	(1,888)
Cash paid	(10,343)	(1,706)
Balance at end of period	8,744	3,763
Employee separation costs
Accrued restructuring and severance costs rollforward
Balance at beginning of period	3,763	1,578
Accruals	15,705	3,891
Adjustment to previous accrual estimate	(594)
Write off of fixed assets and leases and other adjustments	0
Cash paid	(10,130)	(1,706)
Balance at end of period	8,744	3,763
Other exit costs
Accrued restructuring and severance costs rollforward
Balance at beginning of period	0	0
Accruals	2,101	0
Adjustment to previous accrual estimate	0
Write off of fixed assets and leases and other adjustments	(1,888)
Cash paid	(213)	0
Balance at end of period	$ 0	$ 0

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)renewal_Option
Leases [Abstract]
Number of subleases | renewal_Option	2
Lease term	5 years
Loss on early lease terminations	$ 0.7
Sublease rental income, to be received 2021	1.5
Sublease rental income, to be received 2022	1.5
Sublease rental income, to be received 2023	$ 1.5

LEASES - Lease Cost Components

LEASES - Lease Cost Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Total lease cost	$ 3,151	$ 1,309
Selling, general and administrative expenses
Lessee, Lease, Description [Line Items]
Total lease cost	1,760	718
Other (loss) gain
Lessee, Lease, Description [Line Items]
Total lease cost	1,391	591
Sublease Income	$ 2,236	$ 1,386

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in measurement of liabilities:
Operating cash flows from operating leases	$ 3,004	$ 2,446

LEASES - Supplemental Balance S

LEASES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating lease right-of-use assets	$ 2,347	$ 2,776
Liabilities
Current operating lease liabilities	2,683	2,094
Noncurrent operating lease liabilities	2,815	4,820
Total lease liabilities	$ 5,498	$ 6,914
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent

LEASES - Term and Discount Rate

LEASES - Term and Discount Rate Information (Details)	Dec. 31, 2020	Dec. 31, 2019
Weighted-average remaining lease term (years):
Operating leases	2 years 2 months 12 days	3 years 2 months 12 days
Weighted-average discount rate:
Operating leases	6.30%	6.00%

LEASES - Maturity of Lease Liab

LEASES - Maturity of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Lease Payments
2021	$ 2,917
2022	2,308
2023	632
Thereafter	0
Total lease payments	5,857
Less: Interest	359
Present value of lease liabilities	$ 5,498	$ 6,914

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Supply Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2020	May 20, 2020
Legal matters
Purchase obligation, percentage	75.00%
Catalent Pharma Solutions | Supply Commitment
Legal matters
Purchase obligation		$ 1
Jubilant HollisterStier LLC | Supply Commitment
Legal matters
Purchase obligation	$ 2.9

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details)	Aug. 23, 2017defendantaction	Dec. 31, 2020case
Securities Class Action Lawsuit
Legal matters
Number of defendants | defendant	2
Number of shareholder derivative actions filed | action	5
Multidistrict Opioid Litigation
Legal matters
Number of industry-wide opioid litigation cases (more than) | case		2,000

EMPLOYEE BENEFIT PLANS (Details

EMPLOYEE BENEFIT PLANS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of employee's compensation, maximum	5.00%
Contributions to plan	$ 0.2
Defined Contribution Plan Tranches, Tranche One
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent match	100.00%
Employer matching contribution, percent of employee's compensation	3.00%
Defined Contribution Plan Tranches, Tranche Two
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent match	50.00%
Employer matching contribution, percent of employee's compensation	3.00%

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Total	$ 10,924	$ 10,596
Cost of sales (excluding amortization of intangible assets)
Stock-based compensation
Total	92	106
Research and development expenses
Stock-based compensation
Total	268	693
Selling, general and administrative expenses
Stock-based compensation
Total	9,565	9,797
Restructuring charges
Stock-based compensation
Total	$ 999	$ 0

STOCK-BASED COMPENSATION - Gene

STOCK-BASED COMPENSATION - General and ESPP (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 10,924,000	$ 10,596,000
Tax benefit on total stock-based compensation	$ 0	$ 600,000
Weighted-average grant date fair value of awards granted (in dollars per share)	$ 0.41
Options granted (in shares)	0
Options exercised during period (in shares)	0	0
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options	$ 2,700,000
Average vesting period for recognition of unrecognized compensation expense	1 year 4 months 28 days
Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options	$ 200,000
Average vesting period for recognition of unrecognized compensation expense	10 months 20 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, options	$ 1,100,000
Average vesting period for recognition of unrecognized compensation expense	1 year 10 months 13 days
Total fair value of options vested	$ 700,000	$ 1,400,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in dollars per share)	$ 0.41	$ 1.15
Inventory
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 0	$ 0	$ 0

STOCK-BASED COMPENSATION - Sc_2

STOCK-BASED COMPENSATION - Schedule of Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock Options
Assumptions used to calculate the fair value of awards granted
Risk-free interest rate, minimum	0.20%
Risk-free interest rate, maximum	0.35%
Dividend yield	0.00%
Expected stock price volatility	80.00%
Stock Options | Minimum
Assumptions used to calculate the fair value of awards granted
Expected option term	3 years 4 months 24 days
Stock Options | Maximum
Assumptions used to calculate the fair value of awards granted
Expected option term	5 years
ESPP
Assumptions used to calculate the fair value of awards granted
Risk-free interest rate, minimum	0.09%	1.63%
Risk-free interest rate, maximum	0.18%	2.35%
Dividend yield	0.00%	0.00%
Expected option term	6 months	6 months
Expected stock price volatility, minimum	85.80%	57.20%
Expected stock price volatility, maximum	142.30%	132.20%

STOCK-BASED COMPENSATION - 2004

STOCK-BASED COMPENSATION - 2004 Equity Incentive Plan Narrative (Details) - shares	1 Months Ended	12 Months Ended
	May 31, 2004	Dec. 31, 2020
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
The 2004 Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under plan (in shares)	14,450,000
Term of awards (may not exceed)	10 years
Vesting percentage	25.00%
The 2004 Plan | Incentive stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of awards as percentage of the fair value of common stock (at least)	100.00%
The 2004 Plan | Nonstatutory stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of awards as percentage of the fair value of common stock (at least)	80.00%

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Shares
Options granted (in shares)	0
Options exercised (in shares)	0	0
Stock Options | The 2004 Plan
Shares
Options outstanding at the beginning of the period (in shares)	345,206
Options granted (in shares)	0
Options exercised (in shares)	0
Options forfeited (in shares)	0
Options expired (in shares)	(221,706)
Options outstanding at the end of the period (in shares)	123,500	345,206
Options vested and expected to vest at the end of the period (in shares)	123,500
Options exercisable at the end of the period (in shares)	123,500
Weighted- Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)	$ 7.29
Options granted (in dollars per share)	0
Options exercised (in dollars per share)	0
Options forfeited (in dollars per share)	0
Options expired (in dollars per share)	7.76
Options outstanding at the end of the period (in dollars per share)	6.43	$ 7.29
Options vested and expected to vest at the end of the period (in dollars per share)	6.43
Options exercisable at the end of the period (in dollars per share)	$ 6.43
Weighted- Average Remaining Contractual Term
Options outstanding at the end of the period	1 year 10 months 24 days
Options vested and expected to vest at the end of the period	1 year 10 months 24 days
Options exercisable at the end of the period	1 year 10 months 24 days
Aggregate Intrinsic Value (in thousands)
Options outstanding at the end of the period	$ 0
Options vested and expected to vest at the end of the period	0
Options exercisable at the end of the period	$ 0
Stock Options | The 2014 Plan
Shares
Options outstanding at the beginning of the period (in shares)	1,178,045
Options granted (in shares)	200,000
Options exercised (in shares)	0
Options forfeited (in shares)	(46,285)
Options expired (in shares)	(367,372)
Options outstanding at the end of the period (in shares)	964,388	1,178,045
Options vested and expected to vest at the end of the period (in shares)	964,388
Options exercisable at the end of the period (in shares)	716,501
Weighted- Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)	$ 12.64
Options granted (in dollars per share)	0.80
Options exercised (in dollars per share)	0
Options forfeited (in dollars per share)	9.17
Options expired (in dollars per share)	13.68
Options outstanding at the end of the period (in dollars per share)	9.14	$ 12.64
Options vested and expected to vest at the end of the period (in dollars per share)	9.14
Options exercisable at the end of the period (in dollars per share)	$ 11.47
Weighted- Average Remaining Contractual Term
Options outstanding at the end of the period	4 years 9 months 29 days
Options vested and expected to vest at the end of the period	4 years 9 months 29 days
Options exercisable at the end of the period	3 years 7 months 6 days
Aggregate Intrinsic Value (in thousands)
Options outstanding at the end of the period	$ 0
Options vested and expected to vest at the end of the period	0
Options exercisable at the end of the period	$ 0
Stock Options | The 2019 Zyla Plan
Shares
Options outstanding at the beginning of the period (in shares)	0
Options granted (in shares)	4,985,875
Options exercised (in shares)	0
Options forfeited (in shares)	(952,101)
Options expired (in shares)	(90,025)
Options outstanding at the end of the period (in shares)	3,943,749	0
Options vested and expected to vest at the end of the period (in shares)	3,943,749
Options exercisable at the end of the period (in shares)	1,933,604
Weighted- Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)	$ 0
Options granted (in dollars per share)	0.73
Options exercised (in dollars per share)	0
Options forfeited (in dollars per share)	0.70
Options expired (in dollars per share)	1.12
Options outstanding at the end of the period (in dollars per share)	0.73	$ 0
Options vested and expected to vest at the end of the period (in dollars per share)	0.73
Options exercisable at the end of the period (in dollars per share)	$ 0.80
Weighted- Average Remaining Contractual Term
Options outstanding at the end of the period	9 years 3 months 18 days
Options vested and expected to vest at the end of the period	9 years 3 months 18 days
Options exercisable at the end of the period	9 years 6 months
Aggregate Intrinsic Value (in thousands)
Options outstanding at the end of the period	$ 0
Options vested and expected to vest at the end of the period	0
Options exercisable at the end of the period	$ 0

STOCK-BASED COMPENSATION - 2014

STOCK-BASED COMPENSATION - 2014 Omnibus Incentive Plan Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2014	Dec. 31, 2020	Dec. 31, 2019
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
The 2014 Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized under plan (in shares)		13,000,000
Number of shares authorized under plan (in shares)	28,780,000
Shares available for future issuance (in shares)		17,378,077
Vesting period	4 years
The 2014 Plan | Stock Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
The 2014 Plan | Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards (may not exceed)	10 years
The 2014 Plan | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of awards vested		$ 1.1	$ 3.1
Number of units awarded (in shares)		5,985,196
Weighted-average grant date fair value (in dollars per share)		$ 0.97
The 2014 Plan | Restricted stock units | Share-based Payment Arrangement, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Vesting percentage		33.00%
The 2014 Plan | Restricted stock units | Share-based Payment Arrangement, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Vesting percentage		25.00%
The 2014 Plan | Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 months
Number of units awarded (in shares)		0	643,266
Weighted-average grant date fair value (in dollars per share)		$ 0	$ 8.2327
The 2014 Plan | Performance-based Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			0.00%
The 2014 Plan | Performance-based Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			200.00%

STOCK-BASED COMPENSATION - RSU

STOCK-BASED COMPENSATION - RSU and PSU Activity (Details) - The 2014 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Restricted stock units
Number of Shares
Non-vested restricted stock units at the beginning of the period (in shares)	2,936,715
Granted (in shares)	5,985,196
Vested (in shares)	(1,225,191)
Forfeited (in shares)	(2,199,758)
Non-vested restricted stock units at the end of the period (in shares)	5,496,962	2,936,715
Weighted Average Grant Date Fair Value Per Share
Non-vested restricted stock units at the beginning of the period (in dollars per share)	$ 4.64
Granted (in dollars per share)	0.97
Vested (in dollars per share)	4.77
Forfeited (in dollars per share)	1.99
Non-vested restricted stock units at the end of the period (in dollars per share)	$ 2.32	$ 4.64
Weighted Average Remaining Contractual Term (in years)
Non-vested restricted stock units at the end of the period	9 months 18 days
Performance-based Restricted Stock Units
Number of Shares
Non-vested restricted stock units at the beginning of the period (in shares)	983,843
Granted (in shares)	0	643,266
Vested (in shares)	0
Forfeited (in shares)	(78,007)
Non-vested restricted stock units at the end of the period (in shares)	905,836	983,843
Weighted Average Grant Date Fair Value Per Share
Non-vested restricted stock units at the beginning of the period (in dollars per share)	$ 8.11
Granted (in dollars per share)	0	$ 8.2327
Vested (in dollars per share)	0
Forfeited (in dollars per share)	6.74
Non-vested restricted stock units at the end of the period (in dollars per share)	$ 8.23	$ 8.11
Weighted Average Remaining Contractual Term (in years)
Non-vested restricted stock units at the end of the period	8 months 4 days
Aggregate Intrinsic Value (in thousands)
Non-vested restricted stock units at the end of the period	$ 324

STOCK-BASED COMPENSATION - The

STOCK-BASED COMPENSATION - The 2019 Zyla Plan Narrative (Details) $ / shares in Units, $ in Millions	May 20, 2020USD ($)$ / sharesshares	Dec. 31, 2020shares
Zyla Life Sciences
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Merger exchange ratio	2.5
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
The 2019 Zyla Plan | Zyla Life Sciences
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued (in shares)	5,000,000
Issued, average fair market value, per share (in dollars per share) | $ / shares	$ 0.62
Issued, value recognized as merger consideration | $	$ 0.4
The 2019 Zyla Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under plan (in shares)		4,985,875
Shares available for future issuance (in shares)		0
The 2019 Zyla Plan | Stock Options | Zyla Life Sciences
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards (may not exceed)	10 years
Vesting period	3 years
Vesting percentage	33.00%
The 2019 Zyla Plan | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units awarded (in shares)		0

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) $ / shares in Units, $ in Millions	May 20, 2020$ / sharesshares	Dec. 31, 2020USD ($)shares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding | $		$ 6.3	$ 6.3
Options exercised during period (in shares)			0	0
Zyla Life Sciences
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Merger exchange ratio	2.5
Zyla Life Sciences | Iroko | Warrant Agreements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise aggregate ownership percentage maximum threshold	49.00%
Exercise aggregate ownership percentage term	18 months
Zyla Life Sciences | Collegium warrants | Zyla Life Sciences
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price, number of shares outstanding, per share (in dollars per share) | $ / shares	$ 0.0004
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of awards as percentage of the fair value of common stock (at least)			85.00%
Number of shares authorized under plan (in shares)		4,200,000	4,200,000
Shares available for future issuance (in shares)		1,151,033	1,151,033
Shares sold (in shares)			182,726	168,790
Weighted average purchase price of shares sold (in dollars per share) | $ / shares			$ 0.48	$ 1.34
Proceeds from shares sold | $			$ 0.1	$ 0.2
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock in connection with Zyla Merger (in shares)	25,500,000		25,479,000
Issuance of common stock upon exercise of warrant		6,100,000	6,085,000
Shares sold (in shares)			183,000	169,000
Options exercised during period (in shares)				14,000

NET (LOSS) INCOME PER SHARE - S

NET (LOSS) INCOME PER SHARE - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Contingently issuable shares	6,339,765,000
Basic net income (loss) per share
Net loss	$ (28,144)	$ (217,201)
Weighted average common shares outstanding (in shares)	104,835,000	70,716,000
Basic net loss per share (in dollars per share)	$ (0.27)	$ (3.07)
Diluted net income (loss) per share
Net loss	$ (28,144)	$ (217,201)
Weighted average common shares outstanding (in shares)	104,835,000	70,716,000
Add: effect of dilutive securities (in shares)	0	0
Denominator for diluted income (loss) per share (in shares)	104,835,000	70,716,000
Diluted net loss per share (in dollars per share)	$ (0.27)	$ (3.07)

NET (LOSS) INCOME PER SHARE -_2

NET (LOSS) INCOME PER SHARE - Schedule of Anti-Dilutive Shares (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Aug. 13, 2019	Sep. 09, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive common shares (in shares)	18,795	35,276
Convertible Senior Notes, 2.5% | Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate	2.50%			2.50%
Convertible Senior Notes, 5.0% | Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate	5.00%		5.00%
Convertible debt | Convertible Senior Notes, 2.5%
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive common shares (in shares)	1,344	13,895
Convertible debt | Convertible Senior Notes, 5.0%
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive common shares (in shares)	6,831	14,895
Stock options and equivalents
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive common shares (in shares)	10,620	6,486

DISPOSITIONS - Sale of Gralise

DISPOSITIONS - Sale of Gralise (Details) - USD ($) $ in Thousands	Jan. 10, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Co-promotion service income			$ (3,225)	$ 3,948
Gralise | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received, including base purchase price and inventory adjustment	$ 78,600
Consideration received, base purchase price	75,000
Consideration received, inventory adjustment upon disposal	$ 3,600
Consideration receivable as percentage of net sales after closing	75.00%
Threshold for consideration receivable on net sales after closing	$ 70,000
Gain (loss) on sale			(900)
Contingent consideration, payments received			$ 51,600
Gain (loss) on disposal		$ 126,600
Net sale after closing, contingent consideration	$ 51,600
Co-promotion service income		$ 1,300

DISPOSITIONS - Termination of S

DISPOSITIONS - Termination of Slan Agreements (Details) - License Agreement - Slan - USD ($) $ in Millions	Feb. 06, 2020	Nov. 07, 2017	Dec. 31, 2019
Collaboration and License Agreements
License fee		$ 5
License agreement term		10 years
Reimbursable development expenses			$ 2
Reimbursable development expenses, received	$ 2
Possible future payments to be received, based upon commercial sales, if circumstances met	$ 10

DISPOSITIONS - Sale of NUCYNTA

DISPOSITIONS - Sale of NUCYNTA (Details) - NUCYNTA - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Millions	Feb. 13, 2020USD ($)payment	Feb. 11, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	$ 367.9
Proceeds from divestiture of businesses, base purchase price	375
Proceeds from divestiture of businesses, inventory amount	$ 6
Royalties received		$ 13.1
Number of lump sum payments | payment	2
Gain (loss) on disposal				$ (15.8)
Carrying value of intangible derecognized				369.1
Inventory transfer				9
Accrued third-party consent fees				$ 9
Net proceeds received			$ 1
Third-Party Consent Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Lump sum payments obligation	$ 4.5

FAIR VALUE - Schedule of Fair V

FAIR VALUE - Schedule of Fair Value Hierarchy for Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Liabilities:
Short-term contingent consideration	$ 6,776	$ 0
Long-term contingent consideration	31,776	168
Recurring
Assets:
Total	77	9,629
Liabilities:
Short-term contingent consideration	6,776
Long-term contingent consideration	31,776
Contingent consideration liability		168
Total	38,552	168
Recurring | Level 1
Assets:
Total	77	0
Liabilities:
Short-term contingent consideration	0
Long-term contingent consideration	0
Contingent consideration liability		0
Total	0	0
Recurring | Level 2
Assets:
Total	0	9,629
Liabilities:
Short-term contingent consideration	0
Long-term contingent consideration	0
Contingent consideration liability		0
Total	0	0
Recurring | Level 3
Assets:
Total	0	0
Liabilities:
Short-term contingent consideration	6,776
Long-term contingent consideration	31,776
Contingent consideration liability		168
Total	38,552	$ 168
Recurring | Money market funds
Assets:
Cash and cash equivalents	77
Recurring | Money market funds | Level 1
Assets:
Cash and cash equivalents	77
Recurring | Money market funds | Level 2
Assets:
Cash and cash equivalents	0
Recurring | Money market funds | Level 3
Assets:
Cash and cash equivalents	0
Recurring | Collegium warrants
Assets:
Investments	9,629
Recurring | Collegium warrants | Level 1
Assets:
Investments	0
Recurring | Collegium warrants | Level 2
Assets:
Investments	9,629
Recurring | Collegium warrants | Level 3
Assets:
Investments	$ 0

FAIR VALUE - Narrative (Details

FAIR VALUE - Narrative (Details)	May 20, 2020USD ($)	May 31, 2020USD ($)	Jun. 30, 2020USD ($)$ / shares	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Short-term contingent consideration				$ 6,776,000	$ 0
Long-term contingent consideration				$ 31,776,000	168,000
Option pricing model | Revenue volatility
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration, measurement input				0.350
Option pricing model | Discount rate
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration, measurement input				0.060
Option pricing model | Credit spread
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration, measurement input				0.059
Collegium warrants
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Proceeds from sale of investments		$ 6,000,000
Investment, carrying value derecognized		$ 9,600,000
Loss on sale of investments			$ 3,600,000
Collegium Pharmaceutical Inc | Commercialization Agreement
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Warrant, fair value price (in dollars per share) | $ / shares			$ 16.33
Collegium Pharmaceutical Inc | Commercialization Agreement
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Warrant, expected term			2 years 7 months 9 days
Warrant, risk-free rate			0.27%
Zyla Life Sciences
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration liability				$ 38,400,000
Short-term contingent consideration				6,800,000
Long-term contingent consideration				31,600,000
INDOCIN Products | Zyla Life Sciences | Option pricing model
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration, future royalties, estimated revenue, period	10 years
INDOCIN Products | Zyla Life Sciences | Iroko
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent payment consideration, future royalties covenant, product net sales (over)	$ 20,000,000
CAMBIA
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Contingent consideration liability				$ 200,000	$ 200,000

FAIR VALUE - Summary of Changes

FAIR VALUE - Summary of Changes in Fair Value of All Financial Liabilities (Details) - Contingent consideration - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of the period	$ 168	$ 1,038
Contingent consideration acquired with Zyla Merger	39,900	0
Cash payment related to contingent consideration	(3,016)	0
Fair value, end of the period	38,552	168
Costs and expenses
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in fair value	1,500	(983)
Interest expense
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in fair value	$ 0	$ 113

INCOME TAXES - Schedule of Loss

INCOME TAXES - Schedule of Loss Before Income Taxes by Source (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S.	$ (45,327)	$ (222,484)
Outside the U.S.	(186)	0
Net loss before income taxes	$ (45,513)	$ (222,484)

INCOME TAXES - Schedule of (Ben

INCOME TAXES - Schedule of (Benefit) Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal	$ (9,100)	$ (1,231)
State	155	1,715
Total current taxes	(8,945)	484
Deferred:
Federal	(7,037)	(5,767)
State	(1,387)	0
Total deferred taxes	(8,424)	(5,767)
Total tax benefit	$ (17,369)	$ (5,283)

INCOME TAXES - Schedule of Effe

INCOME TAXES - Schedule of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	$ (9,558)	$ (46,722)
State tax, net of federal benefit	276	(3,845)
Goodwill impairment	3,661	0
Disallowed officers' compensation	818	0
Non-deductible transaction cost	451	0
Non-deductible meals and entertainment	148	129
Stock based compensation	17	2,038
Change in valuation allowance	(13,029)	48,943
Uncertain tax provisions	(190)	(5,758)
Non-deductible other expense	37	5,837
Research credit	0	(138)
Intraperiod tax allocations	0	(5,767)
Total tax benefit	$ (17,369)	$ (5,283)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Tax Credit Carryforward [Line Items]
CARES Act, estimated cash tax refund	$ 8,300
Income tax benefit	17,369	$ 5,283
Valuation allowance for deferred tax assets	103,906	90,820
Increase (decrease) in valuation allowance	13,100	48,900
Unrecognized tax benefit that would affect the effective tax rate	4,100	$ 4,000
Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards, not subject to expiration	288,100
Net operating loss carryforwards, subject to expiration	40,100
State Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	$ 181,900

INCOME TAXES - Schedule of Defe

INCOME TAXES - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating losses	$ 81,471	$ 5,885
Tax credit carryforwards	3,360	1,411
Intangible assets	0	82,582
Stock-based compensation	2,999	1,907
Operating lease liabilities	1,248	1,577
Fixed assets	1,315	0
Reserves and other accruals not currently deductible	20,652	9,729
Disallowed interest carryforward	15,496	718
Total deferred tax assets	126,541	103,809
Valuation allowance for deferred tax assets	(103,906)	(90,820)
Deferred tax assets	22,635	12,989
Deferred tax liabilities:
Intangible assets	(21,739)	0
Convertible debt	(459)	(12,247)
Fixed Assets	0	(109)
Operating lease right-of-use assets	(437)	(633)
Net deferred tax liability	$ 0	$ 0

INCOME TAXES - Schedule of Unre

INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of period	$ 4,033	$ 16,064
Increases related to current year tax positions	194	212
Changes in prior year tax positions	(2)	(232)
Decreases related to lapse of statutes	(124)	(12,011)
Unrecognized tax benefits, end of period	$ 4,101	$ 4,033

SUBSEQUENT EVENTS - Narrative (

SUBSEQUENT EVENTS - Narrative (Details) - Subsequent Event - Registered Direct Offering - USD ($) $ / shares in Units, $ in Millions	Feb. 12, 2021	Feb. 09, 2021
Subsequent events
Stock offering, shares sold (in shares)	35,000,000	22,600,000
Stock offering, purchase price (in dollars per share)	$ 0.98	$ 0.62
Stock offering, gross proceeds	$ 34.3	$ 14
Stock offering, net proceeds	$ 32.2	$ 13.1

SCHEDULE II_ VALUATION AND QU_2

SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	May 20, 2020
Movement in valuation and qualifying accounts
Allowance for cash discounts	$ 1,300	$ 1,200
Zyla Life Sciences
Movement in valuation and qualifying accounts
Liabilities assumed from Zyla merger	33,254		$ 33,254
Sales & return allowances, discounts, chargebacks and rebates:
Movement in valuation and qualifying accounts
Balance at Beginning of Year	60,183	76,401
Additions / Charged as a Reduction to Revenue	132,340	163,261
Deductions	(128,081)	(179,479)
Balance at End of Year	64,442	60,183
Deferred tax asset valuation allowance:
Movement in valuation and qualifying accounts
Balance at Beginning of Year	90,820	41,905
Additions / Charged as a Reduction to Revenue	29,833	48,915
Deductions	(16,747)	0
Balance at End of Year	103,906	90,820
Recorded (reversed) valuation allowance	$ 13,100	$ (48,900)