Stockholders' Equity - Stock Based Compensation Related to Stock-Based Awards to Employees and Non-Employees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	$ 510,274	$ 319,133	$ 193,915
Tax benefit from stock-based compensation	(143,892)	(90,542)	(52,559)
Total stock-based compensation, net of tax effect	366,382	228,591	141,356
Cost of revenue [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	48,577	28,617	15,600
Selling and marketing [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	96,076	60,166	36,187
Product development [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	233,006	154,856	98,861
General and administrative [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	132,615	75,494	43,267
RSUs [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	427,173	256,211	142,097
Employee Stock Option [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	36,427	32,277	31,027
Restricted stock units [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	34,008	30,397	20,407
Employee Stock Ownership Plan (ESOP), Plan [Domain]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	16,463	10,777	8,323
Acquisition-related, Modifications And Other [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Total stock-based compensation	22,829	2,595	1,293
Capitalized Website Software [Member]
Share-based Goods and Employee Services Transaction [Line Items]
Costs offsetting to stock-based compensation	$ (26,626)	$ (13,124)	$ (9,232)