Stock Based Compensation - Costs Related to Company's Stock-Based Compensation Plan (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	$ 3,768	$ 4,471	$ 3,553	$ 4,255	$ 2,493	$ 2,376	$ 1,966	$ 4,176	$ 16,047	$ 11,011	$ 11,832
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses									2,895	2,290	2,413
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses									6,077	4,350	5,077
Selling and marketing expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses									$ 7,075	$ 4,371	$ 4,342