Stock-Based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock based compensation expense
Stock based compensation expense	$ 2,877	$ 2,897	$ 5,420	$ 5,292
Cost of product revenues
Stock based compensation expense
Stock based compensation expense	152	189	283	322
Research and development
Stock based compensation expense
Stock based compensation expense	730	717	1,380	1,321
Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	1,995	1,991	$ 3,757	3,649
Employee and non-employee stock options
Stock based compensation expense
Options granted (in shares)			1,568,000
Unrecognized compensation expense	23,400		$ 23,400
Unrecognized compensation expense recognized over weighted average period			2 years 9 months 18 days
Employee stock options
Stock based compensation expense
Stock based compensation expense	2,861	2,813	$ 5,418	5,037
Employee stock options | Cost of product revenues
Stock based compensation expense
Stock based compensation expense	139	157	282	315
Employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense	730	716	1,380	1,321
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	$ 1,992	1,940	$ 3,756	3,401
Non-employee stock options
Stock based compensation expense
Options granted (in shares)			136,046
Options unvested (in shares)	6,930		6,930
Stock based compensation expense	$ 16	84	$ 2	255
Non-employee stock options | Cost of product revenues
Stock based compensation expense
Stock based compensation expense	13	32	1	7
Non-employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense		1
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense	$ 3	$ 51	$ 1	$ 248