Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension and Other Postretirement Plans, Net of Tax	$ (3,899)	$ (2,053)	$ (2,011)	$ (1,702)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(413)	(312)	(345)	(863)
Accumulated Other Comprehensive Income Valuation Allowance Net Of Tax	(2,454)	(1,213)	(1,207)	(1,515)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(6,766)	(3,578)	(3,563)	(4,080)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(3,062)	(121)	(540)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	5	(71)	(20)
OtherComprehensiveIncomeValuationAllowanceChangesInFairValue	0	0	0
Accumulated Other Comprehensive Income Loss Changes In Fair Value Before Tax	(3,057)	(192)	(560)
Other Comprehensive Income, Reclassification of Defined Benefit Plan's Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Tax	(41)	(54)	(48)
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax	(172)	123	1,350
OtherComprehensiveIncomeValuationAllowanceReclassificationToEarnings	0	0	0
Accumulated Other Comprehensive Income Loss Income Reclassification To Earnings Before Tax	(131)	177	1,398
OtherComprehensiveIncomePensionAndOtherPostretirementBenefitPlansIncomeTaxAllocation			0
OtherComprehensiveIncomeDerivativesQualifyingAsHedgesIncomeTaxAllocation			(321)
othercomprehensiveincomevaluationallowanceincometaxallocation			0
Accumulated Other Comprehensive Income Loss Income Tax Allocation Before Tax			(321)
Other Comprehensive Income, Defined Benefit Plans, Tax	(1,175)	(25)	(183)
Other Comprehensive Income, Derivatives Qualifying as Hedges, Tax Effect	66	(19)	(491)
Other Comprehensive Income Valuation Allowance Tax	1,241	6	(308)
Other Comprehensive Income (Loss), Tax	$ 0	$ 0	$ 0