Retirement Benefits (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	$ 2,825	$ (222)	$ (584)
Change in prior service cost	(602)		5
Amortization of:
Prior service (cost) credit	28	12	9
Net loss from previous years	(179)	(270)	(365)
Tax expense related to above items	823	(183)	(374)
Change in unamortized benefit plan costs, net of tax	1,249	(297)	(561)
Pension Benefits
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	2,687	(158)	(524)
Change in prior service cost	(608)		5
Amortization of:
Prior service (cost) credit	(23)	(48)	(50)
Net loss from previous years	(162)	(244)	(337)
Tax expense related to above items	(752)	171	363
Change in unamortized benefit plan costs, net of tax	1,142	(279)	(543)
Medical and Life Benefits
Changes in Unamortized Benefit plan Costs (Table Amounts) [Abstract]
Change in net actuarial loss	138	(64)	(60)
Change in prior service cost	6
Amortization of:
Prior service (cost) credit	51	60	59
Net loss from previous years	(17)	(26)	(28)
Tax expense related to above items	(71)	12	11
Change in unamortized benefit plan costs, net of tax	$ 107	$ (18)	$ (18)