Accumulated Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Beginning balance	$ (2,755)
Current year change	(1,216)
Amortization of actuarial loss and prior service cost	130
Reclassification of derivative financial instruments into earnings	(313)
Change in fair value of derivative financial instruments	190
Ending balance	(3,964)
Estimates reclassification of accumulated other comprehensive loss into earnings	11
Income Tax Benefit (Expense) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Beginning balance	(103)
Current year change
Amortization of actuarial loss and prior service cost
Reclassification of derivative financial instruments into earnings
Change in fair value of derivative financial instruments
Ending balance	(103)
Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Beginning balance	153
Current year change
Amortization of actuarial loss and prior service cost
Reclassification of derivative financial instruments into earnings	(313)
Change in fair value of derivative financial instruments	190
Ending balance	30
Unrealized Gain (Loss) On Investments [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Beginning balance	(5)
Current year change
Amortization of actuarial loss and prior service cost
Reclassification of derivative financial instruments into earnings
Change in fair value of derivative financial instruments
Ending balance	(5)
Pension And Retiree Medical Liability [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Beginning balance	(2,800)
Current year change	(1,216)
Amortization of actuarial loss and prior service cost	130
Reclassification of derivative financial instruments into earnings
Change in fair value of derivative financial instruments
Ending balance	$ (3,886)