Revenue Recognition - Estimated Revenue Expected to be Recognized in Future Related to Performance Obligations (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Product revenue | Remainder 2018
Revenue, Remaining Performance Obligation	$ 4,308
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Product revenue | 2019
Revenue, Remaining Performance Obligation	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Royalty revenue | Remainder 2018
Revenue, Remaining Performance Obligation	$ 10,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Royalty revenue | 2019
Revenue, Remaining Performance Obligation	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Contract Revenue | Remainder 2018
Revenue, Remaining Performance Obligation	$ 4,699
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Contract Revenue | 2019
Revenue, Remaining Performance Obligation	$ 977
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years