Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accrued liabilities
Accrued payroll-related expenses	$ 733	$ 1,045
Accrued manufacturing-related costs	120
Deferred licensing revenue	167	229
Deferred rent	258	248
Accrued sales commissions payable to sales representatives	87	193
Other	561	96
Total accrued liabilities	$ 1,926	$ 1,811