Product Revenue Reserves and Allowances - Product Revenue Allowance and Reserves (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	$ 2,241	$ 0
Provision related to sales in the current year	4,175	3,462
Adjustments related to prior period sales	(337)	0
Deductions applied and payments made	(4,367)	(1,221)
Ending balance	1,712	2,241
Chargebacks, Discounts and Fees [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	1,618	0
Provision related to sales in the current year	2,141	2,301
Adjustments related to prior period sales	(387)	0
Deductions applied and payments made	(2,798)	(683)
Ending balance	574	1,618
Government and Other Rebates [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	271	0
Provision related to sales in the current year	1,056	429
Adjustments related to prior period sales		0
Deductions applied and payments made	(792)	(158)
Ending balance	535	271
Returns [Member]
Disclosure Of Product Revenue Reserves And Allowances [Line Items]
Beginning balance	352	0
Provision related to sales in the current year	978	732
Adjustments related to prior period sales	50	0
Deductions applied and payments made	(777)	(380)
Ending balance	$ 603	$ 352