Product Revenue and Reserves for Variable Consideration - Summary of Product Revenue Allowance and Reserve Categories (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 31,543	$ 23,737
Current provisions related to sales in current year	33,822	19,832
Adjustments related to prior year sales	114	156
Credits/payments made	(32,428)	(19,743)
Ending Balance	33,051	23,982
Chargebacks and Discounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning Balance	738	516
Current provisions related to sales in current year	2,250	1,486
Adjustments related to prior year sales	82
Credits/payments made	(2,353)	(1,495)
Ending Balance	717	507
Rebates, Fees and other Deductions
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning Balance	30,552	22,861
Current provisions related to sales in current year	30,519	17,476
Adjustments related to prior year sales	32	156
Credits/payments made	(29,024)	(17,301)
Ending Balance	32,079	23,192
Returns
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning Balance	253	360
Current provisions related to sales in current year	1,053	870
Credits/payments made	(1,051)	(947)
Ending Balance	$ 255	$ 283