Share Based Awards - Compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	$ 13,506	$ 8,857	$ 21,079	$ 19,147
Cost of revenue
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	1,898	1,266	2,796	2,807
Research and development
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	5,284	3,625	8,343	7,736
Sales and marketing
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	3,389	2,064	5,462	4,338
General and administrative
Allocation of employee service stock-based compensation expense
Stock-based compensation expense	$ 2,935	$ 1,902	$ 4,478	$ 4,266