Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The Company’s unaudited condensed consolidated financial statements have been prepared in accordance with the requirements of the U.S. Securities and Exchange Commission (SEC) for interim financial information. As permitted under Generally Accepted Accounting Principles in the United States (U.S. GAAP), certain notes and other information have been omitted from the interim unaudited condensed consolidated financial statements presented in this Quarterly Report on Form 10-Q. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the Company’s most recent Annual Report on Form 10-K, for the year ended December 31, 2022, filed with the SEC. In management’s opinion, the unaudited condensed consolidated financial statements include all normal and recurring adjustments necessary for a fair presentation of the Company’s financial position, results of operations, and cash flows. The results of operations for any interim period are not necessarily indicative of the Company’s future quarterly or annual results. The Company, which is primarily located in the U.S., operates in one operating segment. Consolidation The Company's unaudited condensed consolidated financial statements include the accounts of Supernus Pharmaceuticals, Inc. and its wholly owned subsidiaries. These are collectively referred to herein as "Supernus" or "the Company." Supernus Pharmaceuticals, Inc. and each of its subsidiaries are distinct legal entities. All significant intercompany transactions and balances have been eliminated in consolidation. The unaudited condensed consolidated financial statements reflect the consolidation of entities in which the Company has a controlling financial interest. In determining whether there is a controlling financial interest, the Company considers if it has a majority of the voting interests of the entity, or if the entity is a variable interest entity (VIE) and if the Company is the primary beneficiary. In determining the primary beneficiary of a VIE, the Company evaluates whether it has both: the power to direct the activities of the VIE that most significantly impact the VIE's economic performance; and the obligation to absorb losses of, or the right to receive benefits from the VIE that could potentially be significant to that VIE. The Company's judgment with respect to its level of influence or control of an entity involves the consideration of various factors, including the form of an ownership interest; representation in the entity's governance; the size of the investment; estimates of future cash flows; the ability to participate in policymaking decisions; and the rights of the other investors to participate in the decision making process, including the right to liquidate the entity, if applicable. If the Company is not the primary beneficiary of the VIE, and an ownership interest is maintained in the entity, the interest is accounted for under the equity or cost methods of accounting, as appropriate. The Company continuously assesses whether it is the primary beneficiary of a VIE as changes to existing relationships or future transactions may affect its conclusions. Use of Estimates The Company bases its estimates on: historical experience; forecasts; information received from its service providers; information from other sources, including public and proprietary sources; and other assumptions that the Company believes are reasonable under the circumstances. Actual results could differ materially from the Company’s estimates. The Company periodically evaluates the methodologies employed in making its estimates. Advertising Expense Advertising expense includes the cost of promotional materials and activities, such as printed materials and digital marketing, marketing programs and speaker programs. The costs of the Company's advertising efforts are expensed as incurred. The Company incurred approximately $25.1 million and $76.9 million in advertising expense for the three and nine months ended September 30, 2023, respectively, and approximately $52.0 million and $112.8 million for the three and nine months ended September 30, 2022. These expenses are recorded as a component of Selling, general and administrative expenses in the unaudited condensed consolidated statements of earnings (loss). Restricted Cash On March 30, 2023, the Company transferred funds totaling $403.8 million, which was reported as restricted cash in the first quarter of 2023, to the Trustee (Wilmington Trust) related to the repayment of the 2023 Notes. On April 1, 2023, the Company paid the total principal amount due of $402.5 million under the 2023 Notes and the remaining outstanding interest due of $1.3 million with the restricted cash. Refer to Note 8, Debt. Line of Credit Line of credit includes borrowings under the uncommitted demand secured line of credit. On February 8, 2023, the Company entered into a credit line agreement (the “Credit Line”) with UBS Bank USA (“UBS”). The Credit Line provides for a revolving line of credit of up to $150 million, which can be drawn at any time. Refer to Note 8, Debt. Recently Issued Accounting Pronouncements Accounting Pronouncements Adopted Accounting Standards Update (ASU) 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity - The new standard, issued in August 2020, simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible debt instruments with cash conversion and beneficial conversion features. ASU 2020-06 eliminates requirements to separately account for liability and equity components of such convertible debt instruments and eliminates the ability to use the treasury stock method for calculating diluted earnings per share for convertible instruments whose principal amount may be settled in whole or in part with equity. Instead, ASU 2020-06 requires (i) the entire amount of the security to be presented as a liability on the balance sheet and (ii) application of the “if-converted” method for calculating diluted earnings per share. This new standard also removes certain settlement conditions required for equity contracts to qualify for the derivative scope exception. The Company adopted the new guidance as of January 1, 2022 using the modified retrospective method of transition which allows for a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. As a result, the cumulative effect of the accounting change increased the carrying amount of the convertible notes, net by $20.6 million, increased retained earnings by $40.6 million, reduced additional paid-in capital by $56.2 million, and decreased deferred tax liabilities by $5.0 million as of January 1, 2022. Upon adoption, the Company began calculating diluted earnings per share under the if-converted method.