Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Revenues	$ 1,644,694	$ 1,340,407	$ 3,217,823	$ 2,610,496
Cost of revenues	1,121,752	914,848	2,168,153	1,784,034
Marketing	197,140	120,763	391,817	257,861
Technology and development	155,061	115,182	298,167	225,492
General and administrative	95,906	60,014	187,395	115,914
Operating income	74,835	129,600	172,291	227,195
Other income (expense):
Interest expense	(35,217)	(13,328)	(61,954)	(23,380)
Interest and other income (expense)	872	1,100	(31,421)	2,501
Income before income taxes	40,490	117,372	78,916	206,316
Provision for income taxes	14,155	46,354	28,885	82,183
Net income	$ 26,335	$ 71,018	$ 50,031	$ 124,133
Earnings per share:
Basic (in dollars per share)	$ 0.06	$ 0.17	$ 0.12	$ 0.30
Diluted (in dollars per share)	$ 0.06	$ 0.16	$ 0.12	$ 0.29
Weighted-average common shares outstanding:
Basic (in shares)	425,340	419,974	424,486	419,349
Diluted (in shares)	436,097	431,441	434,958	431,141