Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]
Revenue	$ 453,502	$ 368,046
Costs and operating expenses:
Cost of revenue	139,612	120,392
Research and development	28,234	21,905
Sales and marketing	81,065	62,690
General and administrative	76,161	55,380
Amortization of acquired intangible assets	6,848	6,060
Restructuring charges	735	431
Total costs and operating expenses	332,655	266,858
Income from operations	120,847	101,188
Interest income	1,639	1,608
Interest expense	(1,941)	0
Other expense, net	(881)	(132)
Income before provision for income taxes	119,664	102,664
Provision for income taxes	46,864	31,177
Net income	$ 72,800	$ 71,487
Net income per share:
Basic (in dollars per share)	$ 0.41	$ 0.40
Diluted (in dollars per share)	$ 0.40	$ 0.39
Shares used in per share calculations:
Basic (in shares)	178,705	177,899
Diluted (in shares)	182,038	181,562