Business Organization	9 Months Ended
Sep. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Organization	Business Organization Supernus Pharmaceuticals, Inc. (the Company, see Consolidation in Note 2, Summary of Significant Accounting Policies) is a biopharmaceutical company focused on developing and commercializing products for the treatment of central nervous system (CNS) diseases. The Company's diverse neuroscience portfolio includes approved treatments for attention-deficit hyperactivity disorder (ADHD), dyskinesia in Parkinson's Disease (PD) patients receiving levodopa-based therapy, hypomobility in PD, postpartum depression (PPD), epilepsy, migraine, cervical dystonia, and chronic sialorrhea. The Company is developing a broad range of novel product candidates for CNS disorders. The Company has nine commercial products that it markets in the United States (U.S.): Qelbree®, GOCOVRI®, Oxtellar XR®, Trokendi XR®, APOKYN®, XADAGO®, MYOBLOC®, ONAPGOTM (formerly known as SPN-830), and ZURZUVAE® (acquired through the acquisition of Sage Therapeutics, Inc.). The Company does not directly market its products outside the U.S. Merger of Equals with Indivior Pharmaceuticals, Inc. On August 1, 2026, the Company entered into an Agreement and Plan Of Merger (the "Merger Agreement"), by and among the Company, Indivior Pharmaceuticals, Inc., a Delaware corporation (Indivior), and Artemis Merger Sub Inc., a Delaware corporation and a wholly-owned subsidiary of Indivior (Merger Sub). Pursuant to the Merger Agreement, and upon the terms and subject to the conditions thereof, Merger Sub will merge with and into the Company (the "Merger"), with the Company continuing as the surviving corporation and a wholly-owned subsidiary of Indivior. Following the completion of the Merger, Indivior will be renamed "Supernus, Inc." and its shares of common stock are expected to continue trading on the Nasdaq Stock Market under the ticker symbol "SUPN". The Merger and the other transactions contemplated by the Merger Agreement are referred to collectively as the "Transactions". The consummation of the Transactions is subject to various regulatory approvals and customary terms and conditions set forth in the Merger Agreement. At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.001 per share, of the Company (each, a "Company Share") issued and outstanding immediately prior to the Effective Time (other than certain excluded shares) will be converted into the right to receive 1.5401 shares of common stock, par value $0.001 per share, of Indivior (each, an "Indivior Share" and, such ratio, the "Exchange Ratio," and the Indivior Shares issuable in the Merger, the "Merger Consideration"). Immediately prior to the Effective Time, stockholders of Indivior will receive a one-time special cash dividend of $1.0 billion. Indivior has secured a debt commitment of $650 million through a term loan facility, and the remaining portion will be funded by existing cash of the then-combined company. The Exchange Ratio is fixed and will not be adjusted for changes in the market price of either the Company Shares or the Indivior Shares. Refer to Note 18, Subsequent Events for further details.

Supernus Pharmaceuticals, Inc. (the Company, see Consolidation in Note 2, Summary of Significant Accounting Policies) is a biopharmaceutical company focused on developing and commercializing products for the treatment of central nervous system (CNS) diseases. The Company's diverse neuroscience portfolio includes approved treatments for attention-deficit hyperactivity disorder (ADHD), dyskinesia in Parkinson's Disease (PD) patients receiving levodopa-based therapy, hypomobility in PD, postpartum depression (PPD), epilepsy, migraine, cervical dystonia, and chronic sialorrhea. The Company is developing a broad range of novel product candidates for CNS disorders.

The Company has nine commercial products that it markets in the United States (U.S.): Qelbree®, GOCOVRI®, Oxtellar XR®, Trokendi XR®, APOKYN®, XADAGO®, MYOBLOC®, ONAPGOTM (formerly known as SPN-830), and ZURZUVAE® (acquired through the acquisition of Sage Therapeutics, Inc.). The Company does not directly market its products outside the U.S.

On August 1, 2026, the Company entered into an Agreement and Plan Of Merger (the "Merger Agreement"), by and among the Company, Indivior Pharmaceuticals, Inc., a Delaware corporation (Indivior), and Artemis Merger Sub Inc., a Delaware corporation and a wholly-owned subsidiary of Indivior (Merger Sub).

Pursuant to the Merger Agreement, and upon the terms and subject to the conditions thereof, Merger Sub will merge with and into the Company (the "Merger"), with the Company continuing as the surviving corporation and a wholly-owned subsidiary of Indivior. Following the completion of the Merger, Indivior will be renamed "Supernus, Inc." and its shares of common stock are expected to continue trading on the Nasdaq Stock Market under the ticker symbol "SUPN". The Merger and the other transactions contemplated by the Merger Agreement are referred to collectively as the "Transactions". The consummation of the Transactions is subject to various regulatory approvals and customary terms and conditions set forth in the Merger Agreement.

At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.001 per share, of the Company (each, a "Company Share") issued and outstanding immediately prior to the Effective Time (other than certain excluded shares) will be converted into the right to receive 1.5401 shares of common stock, par value $0.001 per share, of Indivior (each, an "Indivior Share" and, such ratio, the "Exchange Ratio," and the Indivior Shares issuable in the Merger, the "Merger Consideration"). Immediately prior to the Effective Time, stockholders of Indivior will receive a one-time special cash dividend of $1.0 billion. Indivior has secured a debt commitment of $650 million through a term loan facility, and the remaining portion will be funded by existing cash of the then-combined company. The Exchange Ratio is fixed and will not be adjusted for changes in the market price of either the Company Shares or the Indivior Shares.