Accumulated Other Comprehensive Loss (Schedule Of Income Tax Expense (Benefit) Relating To Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)	$ 15	$ 28	$ 21	$ 12
Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)		32	14	15
Treasury Lock [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)			7	2
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)		$ (4)		$ (5)