Revenue Recognition - Summarize Activity of the Net Product Revenue Allowance and Reserve Categories (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 128,557	$ 65,244
Provision related to current period sales	183,704	94,995
Provision related to prior period sales	(3,209)
Credits/payments made for current period sales	(51,619)	(28,009)
Credits/payments made for prior period sales	(108,651)	(47,659)
Ending balance	148,782	84,571
Trade Allowances
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	29,261	19,495
Provision related to current period sales	30,640	15,881
Credits/payments made for current period sales	(6,872)	(2,624)
Credits/payments made for prior period sales	(29,047)	(8,760)
Ending balance	23,982	23,992
Rebates, Chargebacks and Discounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	90,997	41,634
Provision related to current period sales	133,721	70,410
Provision related to prior period sales	(3,209)
Credits/payments made for current period sales	(33,927)	(18,494)
Credits/payments made for prior period sales	(75,738)	(37,521)
Ending balance	111,844	56,029
Product Returns
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	4,579	2,948
Provision related to current period sales	815	418
Credits/payments made for prior period sales	(145)	(179)
Ending balance	5,249	3,187
Other Incentives
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	3,720	1,167
Provision related to current period sales	18,528	8,286
Credits/payments made for current period sales	(10,820)	(6,891)
Credits/payments made for prior period sales	(3,721)	(1,199)
Ending balance	$ 7,707	$ 1,363