Revenue Recognition (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue
Product revenues	$ 95,619,000	$ 85,487,000	$ 188,244,000	$ 169,467,000
Basic net income (loss) per share (in dollars per share)	$ 0.23	$ (0.08)	$ 0.13	$ (0.10)
Change in Estimate
Disaggregation of Revenue
Product revenues	$ 884,000		$ 884,000
Basic net income (loss) per share (in dollars per share)	$ 0.02		$ 0.02