Summarize Activity of the Net Product Revenue Allowance and Reserve Categories (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 27,198	$ 15,796
Provision related to current period sales	76,790	44,864
Provision related to prior period sales	(1,221)	(553)
Credits/payments made for current period sales	(45,210)	(20,075)
Credits/payments made for prior period sales	(21,623)	(14,187)
Ending balance	35,934	25,845
Trade Allowances
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	3,743	4,296
Provision related to current period sales	15,685	10,048
Provision related to prior period sales	(298)	(87)
Credits/payments made for current period sales	(5,496)	(6,415)
Credits/payments made for prior period sales	(3,107)	(4,180)
Ending balance	10,527	3,662
Rebates, Chargebacks and Discounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	20,915	9,881
Provision related to current period sales	53,078	28,945
Provision related to prior period sales	(841)	(466)
Credits/payments made for current period sales	(34,771)	(10,750)
Credits/payments made for prior period sales	(16,722)	(8,497)
Ending balance	21,659	19,113
Product Returns
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	859	535
Provision related to current period sales	1,259	257
Credits/payments made for current period sales	(21)
Credits/payments made for prior period sales	(24)	(226)
Ending balance	2,073	566
Other Incentives
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	1,681	1,084
Provision related to current period sales	6,768	5,614
Provision related to prior period sales	(82)
Credits/payments made for current period sales	(4,922)	(2,910)
Credits/payments made for prior period sales	(1,770)	(1,284)
Ending balance	$ 1,675	$ 2,504