Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$ 2,197,448	$ 1,963,874	$ 1,577,922
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	725,620	610,943	511,087
Research and development	148,591	125,286	93,879
Sales and marketing	440,988	379,035	280,380
General and administrative	388,265	325,845	255,218
Amortization of acquired intangible assets	27,067	32,057	21,547
Restructuring charges	767	1,189	1,843
Total costs and operating expenses	1,731,298	1,474,355	1,163,954
Income from operations	466,150	489,519	413,968
Interest income	11,200	7,680	6,077
Interest expense	(18,525)	(15,463)	0
Other expense, net	(2,201)	(1,960)	(491)
Income before provision for income taxes	456,624	479,776	419,554
Provision for income taxes	135,218	145,828	126,067
Net income	$ 321,406	$ 333,948	$ 293,487
Net income per share:
Basic (in dollars per share)	$ 1.80	$ 1.87	$ 1.65
Diluted (in dollars per share)	$ 1.78	$ 1.84	$ 1.61
Shares used in per share calculations:
Basic (in shares)	178,391	178,279	178,196
Diluted (in shares)	180,415	181,186	181,783