Stock Based Compensation - Costs Related to Company's Stock-Based Compensation Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	$ 5,107	$ 4,450	$ 11,063	$ 10,259
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	1,129	788	2,339	2,053
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	2,344	1,964	4,940	4,336
Selling and marketing expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	$ 1,634	$ 1,698	$ 3,784	$ 3,870