Retirement Benefits (Unaudited) (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer contributions	$ 77	$ 63	$ 227	$ 210
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	121	114	363	343
Interest cost	306	314	918	944
Expected return on plan assets	(494)	(467)	(1,481)	(1,402)
Amortization of:
Prior service credit	(15)	(14)	(45)	(44)
Net loss from previous years	170	81	511	245
Defined Benefit Plan, Other Costs	0	1	0	1
Net periodic benefit cost	88	29	266	87
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer	20	20	564	59
Medical and Life Benefits
Components of Net Periodic Benefit Cost
Service cost	8	8	26	25
Interest cost	24	25	71	75
Expected return on plan assets	(22)	(21)	(67)	(63)
Amortization of:
Prior service credit	(7)	(12)	(21)	(32)
Net loss from previous years	6	3	20	9
Defined Benefit Plan, Other Costs	0	0	0	0
Net periodic benefit cost	9	3	29	14
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer	$ 19	$ 17	44	$ 43
Voluntary Contributions [Member] | Pension Benefits
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer			$ 500