Retirement Benefits (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	$ (2,438)	$ 2,504	$ 2,825
Change in prior service cost		(2)	(602)
Amortization of:
Prior service (cost) credit	109	109	28
Net loss from previous years	(638)	(448)	(179)
Tax expense (benefit) related to above items	1,177	(860)	(823)
Change in unamortized benefit plan costs	(1,790)	1,303	1,249
Pension Benefits
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	(2,158)	2,353	2,687
Change in prior service cost		(2)	(608)
Amortization of:
Prior service (cost) credit	58	58	(23)
Net loss from previous years	(608)	(427)	(162)
Tax expense (benefit) related to above items	1,075	(788)	(752)
Change in unamortized benefit plan costs	(1,633)	1,194	1,142
Medical and Life Benefits
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	(280)	151	138
Change in prior service cost		0	6
Amortization of:
Prior service (cost) credit	51	51	51
Net loss from previous years	(30)	(21)	(17)
Tax expense (benefit) related to above items	102	(72)	(71)
Change in unamortized benefit plan costs	$ (157)	$ 109	$ 107