Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 15,794,341	$ 11,692,713	$ 8,830,669
Cost of revenues	9,967,538	8,033,000	6,257,462
Marketing	2,369,469	1,436,281	1,097,519
Technology and development	1,221,814	953,710	780,232
General and administrative	630,294	431,043	315,663
Operating income	1,605,226	838,679	379,793
Other income (expense):
Interest expense	(420,493)	(238,204)	(150,114)
Interest and other income (expense)	41,725	(115,154)	30,828
Income before income taxes	1,226,458	485,321	260,507
Provision for (benefit from) income taxes	15,216	(73,608)	73,829
Net income	$ 1,211,242	$ 558,929	$ 186,678
Earnings per share:
Basic (in USD per share)	$ 2.78	$ 1.29	$ 0.44
Diluted (in USD per share)	$ 2.68	$ 1.25	$ 0.43
Weighted-average common shares outstanding:
Basic (in shares)	435,374	431,885	428,822
Diluted (in shares)	451,244	446,814	438,652