Summary of Significant Accounting Policies - Summary of Product Revenue Allowance And Reserve Categories (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Service Fees, Allowances and Chargebacks [Member]
Summary Of Significant Accounting Policies [Line Items]
Beginning Balance	$ 1,733	$ 1,847
Provision related to sales in the current quarter	2,188	1,590
Credits and payments made	(1,969)	(1,852)
Ending Balance	1,952	1,585
Government Rebates and Other Incentives [Member]
Summary Of Significant Accounting Policies [Line Items]
Beginning Balance	530	248
Provision related to sales in the current quarter	383	254
Credits and payments made	(266)	(199)
Adjustments related to prior period sales		95
Ending Balance	647	398
Product Returns [Member]
Summary Of Significant Accounting Policies [Line Items]
Beginning Balance	628	402
Provision related to sales in the current quarter	151	114
Credits and payments made	(9)	(10)
Adjustments related to prior period sales	(111)
Ending Balance	659	506
Purchaser/Provider Discounts and Rebates [Member]
Summary Of Significant Accounting Policies [Line Items]
Beginning Balance	1,832	1,656
Provision related to sales in the current quarter	2,703	526
Credits and payments made	(1,832)	(1,656)
Ending Balance	2,703	526
Product Revenue Allowance and Reserve [Member]
Summary Of Significant Accounting Policies [Line Items]
Beginning Balance	4,723	4,153
Provision related to sales in the current quarter	5,425	2,484
Credits and payments made	(4,076)	(3,717)
Adjustments related to prior period sales	(111)	95
Ending Balance	$ 5,961	$ 3,015