Quarterly Financial Data (unaudited) - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Collaborative Arrangement Agreements [Line Items]
Deferred tax benefit				$ 209,000						$ (277,341)	$ (167,387)	$ 1,512,252
Product revenues, net		$ 1,627,820	$ 1,538,271	$ 1,524,485	$ 1,515,107	$ 1,413,265	$ 949,828	$ 941,293	$ 858,435	$ 6,205,683	$ 4,162,821	$ 3,047,597
Moderna Agreement
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative arrangement, development and commercialization rights potential maximum milestone payments	$ 75,000
CRISPR DMD/DM1
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative arrangement, development and commercialization rights potential maximum milestone payments							$ 175,000
ORKAMBI
Schedule of Collaborative Arrangement Agreements [Line Items]
Product revenues, net						$ 155,800