Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Revenues	$ 2,105,204	$ 1,644,694	$ 4,062,940	$ 3,217,823
Cost of revenues	1,473,098	1,121,752	2,842,638	2,168,153
Marketing	216,029	197,140	424,039	391,817
Technology and development	207,300	155,061	410,808	298,167
General and administrative	138,407	95,906	265,632	187,395
Operating income	70,370	74,835	119,823	172,291
Other income (expense):
Interest expense	(35,455)	(35,217)	(70,992)	(61,954)
Interest and other income (expense)	16,317	872	42,280	(31,421)
Income before income taxes	51,232	40,490	91,111	78,916
Provision for income taxes	10,477	14,155	22,698	28,885
Net income	$ 40,755	$ 26,335	$ 68,413	$ 50,031
Earnings per share:
Basic (in dollars per share)	$ 0.10	$ 0.06	$ 0.16	$ 0.12
Diluted (in dollars per share)	$ 0.09	$ 0.06	$ 0.16	$ 0.12
Weighted-average common shares outstanding:
Basic (in shares)	428,483	425,340	428,300	424,486
Diluted (in shares)	438,154	436,097	438,073	434,958