Summary of Net Product Revenues Earned (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Revenues	$ 1,920	$ 784
Gross Product Revenuea
Disaggregation Of Revenue [Line Items]
Revenues	1,256
Discount and Allowances
Disaggregation Of Revenue [Line Items]
Revenues	(190)
Product Revenue
Disaggregation Of Revenue [Line Items]
Revenues	$ 1,066