Stock-based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	$ 9,997	$ 8,445
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized employee compensation cost	$ 14,900
Unrecognized employee compensation cost, period for recognition	2 years 2 months 12 days
Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized employee compensation cost	$ 60,500
Unrecognized employee compensation cost, period for recognition	2 years 6 months
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	$ 614	545
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	3,437	2,340
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	1,560	1,068
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	$ 4,386	$ 4,492