Revenue Recognition - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregated revenue	$ 2,188	$ 568
Product revenue
Disaggregated revenue	0	0
Royalty revenue
Disaggregated revenue	11	97
Contract revenue
Disaggregated revenue	2,177	471
Transferred at Point in Time
Disaggregated revenue	110	354
Transferred at Point in Time | Product revenue
Disaggregated revenue	0	0
Transferred at Point in Time | Royalty revenue
Disaggregated revenue	11	97
Transferred at Point in Time | Contract revenue
Disaggregated revenue	99	257
Transferred over Time
Disaggregated revenue	2,078	214
Transferred over Time | Product revenue
Disaggregated revenue	0	0
Transferred over Time | Royalty revenue
Disaggregated revenue	0	0
Transferred over Time | Contract revenue
Disaggregated revenue	$ 2,078	$ 214