Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Litigation In July 2020, we received a letter, notifying us that Apotex Inc. and Apotex Corp. (collectively, “Apotex”) submitted to FDA an abbreviated new drug application (“ANDA”) for a generic version of 2.2 mg base/ml Fintepla (fenfluramine hydrochloride) that included “Paragraph IV” certifications (pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV)) with respect to two of our patents covering Fintepla. These patents are listed in FDA’s list of Approved Drug Products with Therapeutic Equivalence Evaluations, commonly referred to as the Orange Book, for Fintepla. The letter included a statement setting forth the basis for Apotex’s opinion that these patents are invalid and/or will not be infringed by the manufacture, use or sale of Apotex’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. In August 2021, we filed a complaint against Apotex Inc. and Apotex Corp. for infringement based on these Paragraph IV certifications. In October 2021, we received a letter notifying us that Apotex had amended its ANDA and submitted additional Paragraph IV certifications with respect two additional Orange Book-listed patents covering Fintepla. The letter included a statement setting forth the basis for Apotex’s opinion that these two additional patents are also invalid and/or will not be infringed by the manufacture, use or sale of Apotex’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. In October 2021, we filed a second complaint against Apotex Inc. and Apotex Corp. for infringement based on these additional paragraph IV certifications. These cases have since been consolidated. In August 2021, we received a letter notifying us that Lupin Limited (“Lupin”) submitted to FDA an abbreviated new drug application (“ANDA”) for a generic version of 2.2 mg base/ml Fintepla (fenfluramine hydrochloride) that contains “Paragraph IV” certifications. These patents are listed in FDA’s list of Approved Drug Products with Therapeutic Equivalence Evaluations, commonly referred to as the Orange Book, for Fintepla. The letter included a statement setting forth the basis for Apotex’s opinion that these patents are invalid and/or will not be infringed by the manufacture, use or sale of Lupin’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. In October 2021, we filed a complaint against Lupin for patent infringement under the Hatch-Waxman Act in the United States District Court for the District of Delaware. Fintepla has Orphan Drug exclusivity, which prevents FDA from approving an ANDA referencing Fintepla until June 2027. We intend to vigorously enforce our intellectual property rights relating to Fintepla. We cannot predict the ultimate outcome of these actions, and we may spend significant resources enforcing and defending these patents. If we are unsuccessful, some or all of our claims in the patents may be narrowed or invalidated and the patent protection for our products could be shortened, allowing for the sale of generic versions of these products earlier than their patent expiration, which could have a significant negative effect on our revenues and results of operations. Merger-Related Litigation Subsequent to year end and following the announcement of the execution of the Agreement and Plan of Merger, dated January 18, 2022, by and among UCB S.A., Zinc Merger Sub, Inc. and Zogenix, Inc. (see Note 19 — Subsequent Event), several complaints related to the merger have been filed. The complaints named as defendants include Zogenix and members of our board of directors as well in one complaint, UCB S.A. and Zinc Merger Sub, Inc. as defendants. The Complaints generally allege that the defendants violated Section 14(d), 14(e) and 20(a) of the Securities Exchange Act of 1934, as well as Rules 14a-9 and 14d-9 promulgated thereunder. Specifically, one or more of the Complaints allege that the Schedule 14D-9 (as amended or supplemented from time to time), the “Schedule 14D-9” filed on February 1, 2022 with the SEC by Zogenix fails to disclose material information and/or materially misrepresents information concerning the sales process leading up to the merger, potential conflicts of interest of BofA Securities and Zogenix insiders, our financial projections, the financial analyses of BofA Securities, and the financial analyses of SVB Leerink. The complaint in the Finuliar Action also asserts state law claims against the members of our board of directors alleging that they breached their fiduciary duty of candor/disclosure by causing or permitting the Schedule 14D-9 to be filed. The relief sought in one or more of the Complaints includes enjoining the consummation of the merger, enjoining defendants from filing any amendment to the Schedule 14D-9 unless certain allegedly material information is included, directing defendants to disseminate an amended Schedule 14D-9 that does not contain any untrue statements of material fact and that states all material facts required in it or necessary to make the statements therein not misleading, declaring that defendants violated Sections 14(d), 14(e), and 20(a) of the Exchange Act and Rules 14a-9 and 14d-9 promulgated thereunder, rescinding, to the extent already consummated, the merger and awarding rescissory damages, directing defendants to account for all alleged damages suffered as a result of defendants’ alleged wrongdoing, awarding the plaintiffs their respective costs and disbursements, and granting other and further equitable relief as the Court may deem just and proper. We cannot currently predict the ultimate outcome of such claims or estimate a range of loss. Indemnification Agreements In the ordinary course of business, we may provide indemnification of varying scope and terms to vendors, lessors, customers and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. These indemnities include indemnities to our directors and officers to the maximum extent permitted under applicable Delaware law. The maximum potential amount of future payments that we could be required to make under these indemnification agreements is, in many cases, unlimited. We have not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims. Unconditional Purchase Obligations We have supply agreements for the manufacture of active pharmaceutical ingredient (API) used in Fintepla and procurement of raw materials (other than the API) used to formulate, fill, test and release an oral solution of Fintepla. As of December 31, 2021, annual minimum purchase commitments under these supply agreements were not material. In addition, we enter into contracts in the normal course of business with CROs for preclinical studies and clinical trials and contract manufacturing organizations for the manufacture of drug materials. The contracts are cancellable, with varying provisions regarding termination. If a contract with a specific vendor were to be cancelled, we would only be obligated for costs of products or services that have been incurred by the vendor prior the effective date of cancellation, plus applicable cancellation fees.