Segment Information (Schedule Of Revenue By Geographic Area) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 787,133	$ 1,020,450	$ 913,591	$ 727,835	$ 737,591	$ 898,099	$ 751,537	$ 646,418	$ 3,449,009	$ 3,033,645	$ 2,743,051
United States [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									1,995,783	1,872,810	1,712,084
All Other Countries [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									$ 1,453,226	$ 1,160,835	$ 1,030,967