CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net revenues	$ 1,059,429	$ 921,580	$ 783,642
Cost of net revenues	528,078	452,720	369,593
Gross profit	531,351	468,860	414,049
Operating expenses:
Technology and development	155,318	133,623	108,995
Sales and marketing	236,749	216,035	189,985
General and administrative	121,019	112,957	93,011
Total operating expenses	513,086	462,615	391,991
Income from operations	18,265	6,245	22,058
Interest expense	(20,998)	(16,732)	(9,446)
Interest and other income, net	744	508	308
Income/(loss) before income taxes	(1,989)	(9,979)	12,920
Benefit from/(provision for) income taxes	1,146	2,119	(3,635)
Net income/(loss)	$ (843)	$ (7,860)	$ 9,285
Net income/(loss) per share:
Basic (in dollars per share)	$ (0.02)	$ (0.20)	$ 0.25
Diluted (in dollars per share)	$ (0.02)	$ (0.20)	$ 0.24
Weighted average shares:
Basic	36,761	38,452	37,680
Diluted	36,761	38,452	39,493