Retirement Benefits (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer contributions	$ 63	$ 63	$ 210	$ 213
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	114	129	343	387
Interest cost	314	279	944	838
Expected return on plan assets	(467)	(452)	(1,402)	(1,357)
Amortization of:
Prior service cost (credit)	(14)	(15)	(44)	(44)
Net loss from previous years	81	152	245	456
Defined Benefit Plan, Other Costs	1	0	1	0
Net periodic benefit cost	29	93	87	280
Employer Contributions
Defined benefit plan, employer contributions			59
Medical and Life Benefits
Components of Net Periodic Benefit Cost
Service cost	8	9	25	27
Interest cost	25	24	75	72
Expected return on plan assets	(21)	(19)	(63)	(57)
Amortization of:
Prior service cost (credit)	(12)	(13)	(32)	(38)
Net loss from previous years	3	8	9	23
Defined Benefit Plan, Other Costs	0	0	0	0
Net periodic benefit cost	3	9	14	27
Employer Contributions
Defined benefit plan, employer contributions			$ 43