Revenue Recognition - Disaggregated Revenues by Timing of Transfer of Goods or Services (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	$ 22,169	$ 6,644
Product Revenue, Net
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	20,362	606
Collaboration and License Revenue
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	1,807	$ 6,038
Transferred at a point in time
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	20,362
Transferred at a point in time | Product Revenue, Net
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	20,362
Transferred over time
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	1,807
Transferred over time | Collaboration and License Revenue
Disaggregation of Revenue [Line Items]
Disaggregated Revenue	$ 1,807