Retirement Benefits (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Employer Contributions
Defined contribution plans cost	$ 66	$ 64	$ 218	$ 225
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	131	130	392	390
Interest cost	296	305	888	915
Expected return on plan assets	(427)	(423)	(1,281)	(1,269)
Amortization of:
Prior service cost (credit)	(15)	6	(44)	18
Net loss from previous years	107	41	321	123
Other	0	0	2	0
Net periodic benefit cost	92	59	278	177
DefinedBenefitPlansRequiredContributionCurrentYear	65		65
Employer Contributions
Employer contributions			349
Defined Benefit Plan Contributions By Employer Voluntary	300
Medical and Life Benefits
Components of Net Periodic Benefit Cost
Service cost	8	8	25	24
Interest cost	28	29	82	87
Expected return on plan assets	(17)	(16)	(51)	(48)
Amortization of:
Prior service cost (credit)	(13)	(13)	(38)	(39)
Net loss from previous years	5	3	15	9
Other	0	0	0	0
Net periodic benefit cost	11	11	33	33
DefinedBenefitPlansRequiredContributionCurrentYear	120		120
Employer Contributions
Employer contributions			$ 75