Stockholders' Equity - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 17,923	$ 10,960	$ 6,113
Cost of providing services
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	4,244	2,658	1,193
Sales and marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	4,490	2,755	1,284
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	7,501	4,517	3,220
Systems development and programming costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,688	$ 1,030	$ 416