Accumulated Other Comprehensive Loss (Schedule Of The Components Of Other Comprehensive Loss) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income Loss Net Of Tax	$ (63)	$ (106)	$ (138)	$ (155)
Current year change	43	32	17
Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income Loss Net Of Tax	(29)	(78)	(99)	(120)
Current year change	49	21	21
Treasury Lock [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income Loss Net Of Tax	(10)	(11)	(22)	(25)
Current year change	1	11	3
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income Loss Net Of Tax	(24)	(17)	(17)	(10)
Current year change	$ (7)		$ (7)