Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net revenue	$ 1,534,786	$ 1,309,239	$ 1,025,064
Costs and expenses:
Cost of revenue	492,493	419,013	346,341
Research and development	90,213	56,736	33,709
Sales and marketing	208,417	166,172	131,174
General and administrative	297,520	244,732	194,957
Depreciation and amortization	313,007	249,845	195,412
Total costs and expenses	1,401,650	1,136,498	901,593
Income from operations	133,136	172,741	123,471
Other income (expense):
Interest expense	(3,118)	(4,749)	(5,848)
Interest and other income (expense)	741	15	(1,194)
Total other income (expense)	(2,377)	(4,734)	(7,042)
Income before income taxes	130,759	168,007	116,429
Income taxes	44,022	62,589	40,018
Net income	86,737	105,418	76,411
Other comprehensive income, net of tax
Foreign currency translation adjustments	3,553	6,643	(2,316)
Other comprehensive income (loss)	3,553	6,643	(2,316)
Comprehensive income	$ 90,290	$ 112,061	$ 74,095
Net income per share
Basic	$ 0.63	$ 0.78	$ 0.59
Diluted	$ 0.61	$ 0.75	$ 0.55
Weighted average number of shares outstanding
Basic	138,577	135,279	129,922
Diluted	143,011	141,265	138,064