Revenue Recognition - Disaggregated Revenues by Timing of Transfer of Goods or Services (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 36,799	$ 14,177	$ 87,392	$ 24,832
Product revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	35,743	7,176	83,269	10,047
Collaboration and license revenue
Disaggregation of Revenue [Line Items]
Total revenues	1,056	7,001	4,123	14,785
Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	35,743	7,176	83,269	10,047
Transferred at a point in time | Product revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	35,743	7,176	83,269	10,047
Transferred at a point in time | Collaboration and license revenue
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	1,056	7,001	4,123	14,785
Transferred over time | Product revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Transferred over time | Collaboration and license revenue
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,056	$ 7,001	$ 4,123	$ 14,785