Retirement Benefits (Unaudited) (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer contributions	$ 65	$ 74	$ 150	$ 147
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	121	115	242	229
Interest cost	306	315	612	630
Expected return on plan assets	(493)	(468)	(987)	(935)
Amortization of:
Prior service credit	(15)	(15)	(30)	(30)
Net loss from previous years	170	82	341	164
Net periodic benefit cost	89	29	178	58
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer	19	18	544	39
Medical and Life Benefits
Components of Net Periodic Benefit Cost
Service cost	9	9	18	17
Interest cost	23	24	47	50
Expected return on plan assets	(23)	(21)	(45)	(42)
Amortization of:
Prior service credit	(7)	(13)	(14)	(20)
Net loss from previous years	8	4	14	6
Net periodic benefit cost	10	3	20	11
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer	$ 19	$ 19	25	$ 26
Voluntary Contributions [Member] | Pension Benefits
Defined Benefit Plan, Expected Contributions in Current Fiscal Year [Abstract]
Defined benefit plan, contributions by Employer			$ 500