Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenues	$ 3,999,374	$ 2,984,859	$ 11,607,500	$ 8,406,958
Cost of revenues	2,412,346	1,992,980	6,898,288	5,552,312
Marketing	435,269	312,490	1,441,271	858,083
Technology and development	327,026	255,236	944,969	779,427
General and administrative	344,065	215,526	933,513	623,760
Operating income	480,668	208,627	1,389,459	593,376
Other income (expense):
Interest expense	(108,862)	(60,688)	(291,686)	(162,912)
Interest and other income (expense)	7,004	(31,702)	9,289	(76,473)
Income before income taxes	378,810	116,237	1,107,062	353,991
Provision for (benefit from) income taxes	(24,025)	(13,353)	29,754	(19,421)
Net income	$ 402,835	$ 129,590	$ 1,077,308	$ 373,412
Earnings per share:
Basic (in dollars per share)	$ 0.92	$ 0.30	$ 2.48	$ 0.87
Diluted (in dollars per share)	$ 0.89	$ 0.29	$ 2.39	$ 0.84
Weighted-average common shares outstanding:
Basic (in shares)	435,809	432,404	435,033	431,473
Diluted (in shares)	451,919	447,362	451,283	446,367