Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Revenue	$ 476,035	$ 378,106	$ 929,537	$ 746,152
Costs and operating expenses:
Cost of revenue	149,318	124,705	288,930	245,097
Research and development	32,052	20,597	60,286	42,502
Sales and marketing	91,462	67,825	172,527	130,515
General and administrative	81,880	61,351	158,041	116,731
Amortization of acquired intangible assets	8,403	5,734	15,251	11,794
Restructuring charges	569	391	1,304	822
Total costs and operating expenses	363,684	280,603	696,339	547,461
Income from operations	112,351	97,503	233,198	198,691
Interest income	1,740	1,477	3,379	3,085
Interest expense	(4,516)	0	(6,457)	0
Other (expense) income, net	(899)	341	(1,780)	209
Income before provision for income taxes	108,676	99,321	228,340	201,985
Provision for income taxes	35,790	37,426	82,654	68,603
Net income	$ 72,886	$ 61,895	$ 145,686	$ 133,382
Net income per share:
Basic (in dollars per share)	$ 0.41	$ 0.35	$ 0.82	$ 0.75
Diluted (in dollars per share)	$ 0.40	$ 0.34	$ 0.80	$ 0.73
Shares used in per share calculations:
Basic (in shares)	178,081	177,891	178,393	177,895
Diluted (in shares)	180,841	181,388	181,439	181,475