Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies
Fair value inputs, future outcomes, minimum equity financing proceeds	$ 5,000
Deferred revenue	2,900	$ 2,600
Deferred cost of sales	1,100	1,200
Deferred income on shipments to distributors	1,827	1,440
Income Taxes
Interest and penalties on unrecognized tax benefits	$ 0	$ 0	$ 0