Retirement Benefits (Reconciliation Of Changes In Pension, Retiree Medical, Other Benefit Obligations And Fair Value Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Ending balance	$ 8,132	$ 7,773
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Obligation at January 1	12,968	12,003
Service cost	386	366	333
Interest cost	757	737	712
Actuarial (gain) loss	1,237	442
Plan amendments		1
Benefit payments	(780)	(581)
Obligation at December 31	14,568	12,968	12,003
Beginning balance	7,773	7,051
Actual return on plan assets	614	837
Employer contributions	525	466
Ending balance	8,132	7,773	7,051
Funded status at December 31	(6,436)	(5,195)
Retiree Medical And Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Obligation at January 1	3,097	2,827
Service cost	61	60	59
Interest cost	174	165	179
Actuarial (gain) loss	(63)	263
Plan amendments	(3)	(78)
Benefit payments	(144)	(140)
Obligation at December 31		3,097	2,827
Beginning balance	234	206
Actual return on plan assets	(6)	17
Employer contributions	121	151
Ending balance	205	234	206
Funded status at December 31	$ (2,917)	$ (2,863)