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Stock-based Awards (Details 3 - Stock comp by FSLI) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-based Compensation Cost
Stock-based compensation expense	$ 7,191		$ 10,247	$ 31,382	$ 28,316
Amount capitalized to internal software use	431		551	1,409	1,358
Total stock-based compensation cost	7,622		10,798	32,791	29,674
Certain executive-level employees
Stock-based Compensation Cost
Termination benefits		$ 7,200		7,200
Cost of revenue
Stock-based Compensation Cost
Stock-based compensation expense	549		469	1,601	1,210
Sales and marketing
Stock-based Compensation Cost
Stock-based compensation expense	2,697		3,852	10,885	10,522
Technology and development
Stock-based Compensation Cost
Stock-based compensation expense	1,615		2,829	7,024	7,880
General and administrative
Stock-based Compensation Cost
Stock-based compensation expense	$ 2,330		$ 3,097	$ 11,872	$ 8,704