Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued liabilities
Accrued payroll-related expenses	$ 1,045	$ 636
Accrued manufacturing-related costs		339
Deferred licensing revenue	229	250
Deferred rent	248	220
Accrued sales commissions payable to sales representatives	193	165
Other	96	145
Total accrued liabilities	$ 1,811	$ 1,755