Retirement Benefits (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Employer Contributions
Defined contribution plans cost	$ 76	$ 76	$ 152	$ 161
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
DefinedBenefitPlansRequiredContributionCurrentYear	65		65
Components of Net Periodic Benefit Cost
Service cost	130	130	261	260
Interest cost	296	305	592	610
Expected return on plan assets	(427)	(423)	(854)	(846)
Amortization of:
Prior service cost (credit)	(14)	6	(29)	12
Net loss from previous years	107	41	214	82
Other	0	0	2	0
Net periodic benefit cost	92	59	186	118
Employer Contributions
Employer contributions			33
Medical and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
DefinedBenefitPlansRequiredContributionCurrentYear	120		120
Components of Net Periodic Benefit Cost
Service cost	9	8	17	16
Interest cost	27	29	54	58
Expected return on plan assets	(17)	(16)	(34)	(32)
Amortization of:
Prior service cost (credit)	(13)	(13)	(25)	(26)
Net loss from previous years	5	3	10	6
Other	0	0	0	0
Net periodic benefit cost	11	11	22	22
Employer Contributions
Employer contributions			$ 46