Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 1,373,947	$ 1,158,538	$ 1,023,586
Cost and operating expenses:
Cost of revenues	431,911	374,543	303,403
Research and development	74,744	52,333	54,766
Sales and marketing	304,404	227,331	226,704
General and administrative	227,033	191,726	167,779
Amortization of other intangible assets	20,962	17,070	16,657
Restructuring charge	406	4,886	0
Total cost and operating expenses	1,059,460	867,889	769,309
Income from operations	314,487	290,649	254,277
Interest income	6,412	10,670	12,163
Interest expense	0	0	(1,697)
Other income (expense), net	649	6,125	(2,468)
Gain (loss) on investments, net	43	(249)	396
Loss on early extinguishment of debt	0	0	(299)
Income before provision for income taxes	321,591	307,195	262,372
Provision for income taxes	117,602	106,291	91,152
Net income	$ 203,989	$ 200,904	$ 171,220
Net income per weighted average share:
Basic (in dollars per share)	$ 1.15	$ 1.09	$ 0.97
Diluted (in dollars per share)	$ 1.12	$ 1.07	$ 0.90
Shares used in per share calculations:
Basic (in shares)	177,900	183,866	177,309
Diluted (in shares)	181,749	187,556	190,650