Stock-based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	$ 9,444	$ 8,335	$ 19,441	$ 16,780
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized employee compensation cost	16,700		$ 16,700
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	54,300		$ 54,300
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	583	552	$ 1,197	1,097
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	3,253	2,704	6,690	5,044
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	1,513	1,063	3,073	2,131
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation	$ 4,095	$ 4,016	$ 8,481	$ 8,508