Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenue	$ 2,340,049	$ 2,197,448	$ 1,963,874
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	809,001	725,620	610,943
Research and development	167,628	148,591	125,286
Sales and marketing	426,967	440,988	379,035
General and administrative	439,916	388,265	325,845
Amortization of acquired intangible assets	26,642	27,067	32,057
Restructuring charges	10,301	767	1,189
Total costs and operating expenses	1,880,455	1,731,298	1,474,355
Income from operations	459,594	466,150	489,519
Interest income	14,702	11,200	7,680
Interest expense	(18,638)	(18,525)	(15,463)
Other income (expense), net	3,788	(2,201)	(1,960)
Income before provision for income taxes	459,446	456,624	479,776
Provision for income taxes	143,314	135,218	145,828
Net income	$ 316,132	$ 321,406	$ 333,948
Net income per share:
Basic (in dollars per share)	$ 1.81	$ 1.80	$ 1.87
Diluted (in dollars per share)	$ 1.79	$ 1.78	$ 1.84
Shares used in per share calculations:
Basic (in shares)	174,917	178,391	178,279
Diluted (in shares)	176,215	180,415	181,186