Comprehensive Income (Schedule Of Comprehensive Income) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Comprehensive Income [Abstract]
Net income	$ 37,126	$ 19,505	$ 72,361	$ 39,314
Foreign currency translation adjustment, net of tax expense	(832)	1,052	(122)	(871)
Interest rate cash flow hedges, net of tax expense		812	547	2,109
Unrealized gains (losses) on short-term investments, net of tax expense (benefit)		3	(13)	3
Comprehensive income	36,294	21,372	72,773	40,555
Foreign currency translation adjustment, net of tax expense	0	61	0	56
Interest rate cash flow hedges, net of tax expense	0	519	349	1,348
Unrealized gains (losses) on short-term investments, net of tax expense (benefit)	$ 0	$ 3	$ (8)	$ 3