Stock-Based Compensation - Distribution of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share Based Compensation Expense [Line Items]
Stock-based compensation	$ 443	$ 133	$ 733	$ 320
Cost of Revenue
Share Based Compensation Expense [Line Items]
Stock-based compensation	9	4	22	11
Research and Development
Share Based Compensation Expense [Line Items]
Stock-based compensation	110	25	187	73
Selling, General and Administrative
Share Based Compensation Expense [Line Items]
Stock-based compensation	$ 324	$ 104	$ 524	$ 236