DISPOSITIONS	12 Months Ended
DISPOSITIONS	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 Commercialization Agreement. The Commercialization Agreement terminated at closing with certain specified provisions of the Commercialization Agreement surviving in accordance with the terms of the Purchase Agreement.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. During the year ended December 31, 2020, the Company recognized a net loss of $15.8 million in Other income which was comprised of the $367.9 million in consideration received less the $369.1 million carrying value of the NUCYNTA intangible derecognized, $9.0 million in net book value of inventory transferred, and $9.0 million in accrued third-party consent fees. During the year ended December 31, 2020, the Company received $1.0 million in net proceeds from Collegium for settlement of expense reimbursement pursuant to the Purchase Agreement which was recognized as a gain in Other income.