COMMITMENTS AND CONTINGENCIES	12 Months Ended
COMMITMENTS AND CONTINGENCIES	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Contingencies From time to time the Company is involved in legal actions arising in the normal course of its business. The process of resolving matters through litigation or other means is inherently uncertain and it is possible that an unfavorable resolution of these matters could adversely affect the Company, its results of operations, financial condition or cash flows. The Company’s general practice is to expense legal fees as services are rendered in connection with legal matters, and to accrue for liabilities when losses are probable and reasonably estimable based on existing information. The Company accrues for the best estimate of a loss within a range; however, if no estimate in the range is better than any other, then the minimum amount in the range is accrued. Liabilities are evaluated and refined each reporting period as additional information is known. Any receivables for insurance recoveries for these liability claims are recorded as assets when it is probable that a recovery will be realized. The Company was involved in a purported shareholder class action lawsuit filed against the Company and certain officers and directors alleging violations under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 as amended (the Exchange Act) for making materially false or misleading statements regarding the clinical trials and Biologics License Application (BLA) for ROCTAVIAN (formerly known as valoctocogene roxaparvovec) by purportedly failing to disclose that differences between the Company’s Phase 1/2 and Phase 3 clinical studies limited the ability of the Phase 1/2 study to support ROCTAVIAN’s durability of effect and, as a result, that it was foreseeable that the FDA would not approve the BLA without additional data. On March 21, 2023, the Court entered an order staying all proceedings and vacating all deadlines because the parties agreed to settle the case through a binding term sheet. The Court preliminarily approved the settlement on June 8, 2023. On November 14, 2023, the court granted final approval of the settlement and entered final judgment. The Company maintains directors and officers liability insurance that covers exposure related to this class action lawsuit. As of December 31, 2022, the Company had recorded an estimated long-term loss contingency of $13.0 million on the Company’s Consolidated Balance Sheets. The same amount was recorded for expected insurance recoveries. During 2023, the amount recorded on the Company's Consolidated Balance Sheets increased to $39.0 million based on the final settlement and was reclassified to short term. As of December 31, 2023, the $39.0 million settlement liability and related receivable have been released following the final judgment. There was a net zero impact on the Company's Consolidated Statements of Cash Flows and Consolidated Statement of Operations in the years presented. The Company recently received a subpoena from the U.S. Department of Justice (DOJ) requesting that the Company produce certain documents regarding sponsored testing programs relating to VIMIZIM and NAGLAZYME. The Company has produced the requested documents in response to the subpoena and is cooperating fully. The Company is unable to make any assurances regarding the outcome of the investigation by the DOJ, or the impact, if any, that such investigation may have on the Company’s business, Consolidated Balance Sheets, Statements of Operations or Statements of Cash Flows. Contingent Payments As of December 31, 2023, the Company was subject to contingent payments, primarily comprised of development, regulatory and commercial milestones. Those considered reasonably possible totaled $763.3 million, of this amount the Company may pay up to $30.1 million in 2024 if certain contingencies are met. $591.5 million of the total balance related to early-stage development programs licensed from two third parties. Other Commitments The Company uses experts and laboratories at universities and other institutions to perform certain R&D activities. These amounts are included as R&D expense as services are provided. In the normal course of business, the Company enters into various firm purchase commitments primarily to procure active pharmaceutical ingredients, certain inventory-related items and certain third-party R&D services, production services and facility construction services. The Company also has commitments related to enterprise resource planning system implementation costs. As of December 31, 2023, such commitments were estimated at $354.1 million, of which $325.9 million is expected to be paid in 2024 as underlying goods and services are received. The Company has also licensed technology from third parties, for which it is required to pay royalties upon future sales, subject to certain annual minimums.