Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]
Revenues	$ 248,796	$ 236,447
Costs and expenses:
Cost of revenues	48,026	47,254
Sales and marketing	20,289	18,104
Research and development	18,439	18,176
General and administrative	22,457	19,649
Total costs and expenses	109,211	103,183
Operating income	139,585	133,264
Interest expense	(21,385)	(12,596)
Non-operating income (loss), net	6,516	(5,777)
Income before income taxes	124,716	114,891
Income tax expense	(30,293)	(30,378)
Net Income	94,423	84,513
Change in unrealized gain on investments, net of tax	8	(267)
Realized gain on investments, net of tax, included in net income	5	(20)
Other comprehensive income (loss)	13	(287)
Comprehensive Income	$ 94,436	$ 84,226
Basic income (loss) per share
Continuing operations	$ 0.71	$ 0.55
Diluted income (loss) per share
Continuing operations	$ 0.64	$ 0.52
Shares used to compute net income per share
Basic	133,417	152,543
Diluted	148,600	161,346