License and Collaboration Agreements - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Feb. 12, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net		$ 359,484	$ 231,495
Collaboration Receivable Current		30,092		$ 29,786
Development Milestone and Upfront Fee Recognized as Research and Development Expense		0	500
ELEVIDYS [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net		133,936	0
Collaborative Arrangement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for option exercise			121,800
Collaborative Arrangement | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent research milestone payments		34,800
Development Milestone and Upfront Fee Recognized as Research and Development Expense		3,200,000
Collaborative Arrangement | Roche Holding A.G. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net	$ 48,000	48,000	22,000
Deferred Revenue		437,000		485,000
Deferred Revenue, Current		112,000		48,000
Research and development expense		21,700	20,300
Collaboration Receivable		30,100		$ 29,800
Collaborative Arrangement | Roche Holding A.G. [Member] | ELEVIDYS [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Receivable Current		5,800	$ 0
Inventory Cost		$ 1,700