Stockholders' Equity - Stock-Based Compensation Expense Recognized in Company's Condensed Consolidated Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 27,662	$ 27,280	$ 86,473	$ 75,310
Cost of revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,145	2,270	6,243	5,666
Sales and marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	7,256	7,250	22,199	19,796
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 18,261	$ 17,760	$ 58,031	$ 49,848