Equity incentive Plans - Summary of Compensation Costs Related to Stock Options Included in Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 3,332	$ 2,448	$ 6,378	$ 5,550
Cost of Revenue
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	113	92	243	176
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	978	652	1,895	1,468
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	943	592	1,849	1,549
General and Administration
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 1,298	$ 1,112	$ 2,391	$ 2,357