Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Revenues	$ 236,447	$ 205,726
Costs and expenses:
Cost of revenues	47,254	41,256
Sales and marketing	18,104	27,815
Research and development	18,176	14,765
General and administrative	19,649	23,508
Restructuring charges	0	(548)
Total costs and expenses	103,183	106,796
Operating income	133,264	98,930
Interest expense	(12,596)	(12,340)
Non-operating (loss) income, net	(5,777)	807
Income from continuing operations before income taxes	114,891	87,397
Income tax expense	(30,378)	(21,292)
Income from continuing operations, net of tax	84,513	66,105
Income (loss) from discontinued operations, net of tax	0	1,904
Net income	84,513	68,009
Change in unrealized gain on investments, net of tax	(267)	(5)
Realized gain on investments, net of tax, included in net income	(20)	(5)
Other comprehensive income (loss)	(287)	(10)
Comprehensive income	$ 84,226	$ 67,999
Basic income (loss) per share
Continuing operations	$ 0.55	$ 0.41
Discontinued operations	$ 0.00	$ 0.02
Net income	$ 0.55	$ 0.43
Diluted income (loss) per share
Continuing operations	$ 0.52	$ 0.41
Discontinued operations	$ 0.00	$ 0.01
Net income	$ 0.52	$ 0.42
Shares used to compute net income per share
Basic	152,543	159,344
Diluted	161,346	162,881