Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 86,271	$ 88,900	$ 85,573	$ 82,630	$ 81,241	$ 79,941	$ 88,837	$ 81,359	$ 343,374
Product revenue, net
Disaggregation of Revenue [Line Items]
Revenues									341,136
License and royalty revenues
Disaggregation of Revenue [Line Items]
Revenues									2,238
U.S.
Disaggregation of Revenue [Line Items]
Revenues									288,580
U.S. | Product revenue, net
Disaggregation of Revenue [Line Items]
Revenues									288,580
U.S. | License and royalty revenues
Disaggregation of Revenue [Line Items]
Revenues									0
International
Disaggregation of Revenue [Line Items]
Revenues									54,794
International | Product revenue, net
Disaggregation of Revenue [Line Items]
Revenues									52,556
International | License and royalty revenues
Disaggregation of Revenue [Line Items]
Revenues									$ 2,238