Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation (benefit) expense	$ (2,895)	$ 14,119	$ 39,604
Cost of services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation (benefit) expense	(72)	381	4,156
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation (benefit) expense	266	1,649	4,276
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation (benefit) expense	$ (3,089)	$ 12,089	$ 31,172