Stockholders' Equity - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,264	$ 4,188	$ 20,169	$ 12,991
Cost of providing services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,605	1,079	5,044	3,051
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,491	1,029	5,119	3,255
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,544	1,633	8,161	5,497
Systems development and programming costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 624	$ 447	$ 1,845	$ 1,188