Retirement Benefits (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Pension Benefits	Jun. 30, 2012 Pension Benefits	Jun. 30, 2013 Pension Benefits	Jun. 30, 2012 Pension Benefits	Jun. 30, 2013 Pension Benefits Voluntary Contributions [Member]	Jun. 30, 2013 Medical and Life Benefits	Jun. 30, 2012 Medical and Life Benefits	Jun. 30, 2013 Medical and Life Benefits	Jun. 30, 2012 Medical and Life Benefits	Dec. 31, 2013 Pension Employer Required Minimum Contribution	Dec. 31, 2013 OPEB Employer Required Minimum Contribution
Components of Net Periodic Benefit Cost
Service cost					$ 129	$ 130	$ 258	$ 261		$ 9	$ 9	$ 18	$ 17
Interest cost					280	296	559	592		24	27	48	54
Expected return on plan assets					(452)	(427)	(905)	(854)		(19)	(17)	(38)	(34)
Amortization of:
Prior service cost (credit)					(15)	(14)	(29)	(29)		(13)	(13)	(25)	(25)
Net loss from previous years					152	107	304	214		8	5	15	10
Defined Benefit Plan, Other Costs					0	0	0	2		0	0	0	0
Net periodic benefit cost					94	92	187	186		9	11	18	22
Employer Contributions
Defined benefit plan, expected contributions in current fiscal year														66	110
Defined benefit plan, employer contributions							543		500			63
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer contributions	$ 75	$ 76	$ 150	$ 152