Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue	$ 1,963,874	$ 1,577,922	$ 1,373,947
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	610,943	511,087	529,900
Research and development	125,286	93,879	74,744
Sales and marketing	379,035	280,380	223,348
General and administrative	325,845	255,218	210,100
Amortization of acquired intangible assets	32,057	21,547	20,962
Restructuring charges	1,189	1,843	406
Total costs and operating expenses	1,474,355	1,163,954	1,059,460
Income from operations	489,519	413,968	314,487
Interest income	7,680	6,077	6,455
Interest expense	(15,463)	0	0
Other (expense) income, net	(1,960)	(491)	649
Income before provision for income taxes	479,776	419,554	321,591
Provision for income taxes	145,828	126,067	117,602
Net income	$ 333,948	$ 293,487	$ 203,989
Net income per share:
Basic (in dollars per share)	$ 1.87	$ 1.65	$ 1.15
Diluted (in dollars per share)	$ 1.84	$ 1.61	$ 1.12
Shares used in per share calculations:
Basic (in shares)	178,279	178,196	177,900
Diluted (in shares)	181,186	181,783	181,749