Revenue - Product Revenue Allowance and Reserves (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	$ 1,712	$ 2,241
Provision related to sales in the current year	1,891	1,048
Adjustments related to prior period sales	(172)	(217)
Deductions applied and payments made	(1,466)	(1,096)
Ending balance	1,965	1,976
Chargebacks, Discounts and Fees [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	574	1,618
Provision related to sales in the current year	1,041	612
Adjustments related to prior period sales	(50)	(267)
Deductions applied and payments made	(809)	(639)
Ending balance	756	1,324
Government and Other Rebates [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	535	271
Provision related to sales in the current year	679	175
Adjustments related to prior period sales	(22)
Deductions applied and payments made	(473)	(262)
Ending balance	719	184
Returns [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	603	352
Provision related to sales in the current year	171	261
Adjustments related to prior period sales	(100)	50
Deductions applied and payments made	(184)	(195)
Ending balance	$ 490	$ 468