Stockholders' Equity - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 4,883	$ 2,923	$ 8,803	$ 5,070
Cost of Providing Services
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,214	801	1,972	1,255
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,309	774	2,226	1,291
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,842	1,045	3,863	2,053
Systems Development and Programming Costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 518	$ 303	$ 742	$ 471