Summary of Other Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	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
Nonoperating Income Expense [Abstract]
Interest expense									$ (59,947)		$ (30,669)	$ (33,709)
Interest income									2,970		7,238	6,810
Amortization of investment discount									4,489		15,350	8,573
Gain from sale of Priority Review Voucher				$ 108,069					108,069
Loss on contingent consideration		$ (45,000)							(45,000)	[1]
Other expense									517		(236)	(656)
Total other income (loss)	$ (17,769)	$ (59,335)	$ (12,447)	$ 100,649	$ (4,773)	$ (2,510)	$ (862)	$ (172)	$ 11,098		$ (8,317)	$ (18,982)

[1] The loss on contingent consideration is related to the fair value adjustment of the regulatory-related contingent payments that are accounted for as derivatives. Please see Note 5. Fair Value Measurements for further details.