Retirement Plans (Reconciliation Of Benefit Obligations And Plan Or Trust Assets And Resulting Funded Status Of Defined Benefit Retirement Plans) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits
Change in Benefit Obligation
Service cost	$ (266)	$ (245)	$ (211)
Interest cost	(523)	(517)	(509)
Other Postretirement Benefit Plans, Defined Benefit
Change in Benefit Obligation
Service cost	(12)	(13)	(10)
Interest cost	(59)	(62)	(59)
Change in Benefit Obligation [Member] | Pension Benefits
Change in Benefit Obligation
Benefit obligation at beginning of year	(10,242)	(9,238)
Service cost	(266)	(245)
Interest cost	(523)	(517)
Amendments	0	(16)
Actuarial loss	(1,527)	(670)
Settlement/curtailment/other	(7)	(2)
Benefits paid	451	446
Benefit obligation at end of year	(12,114)	(10,242)
Change in Benefit Obligation [Member] | Other Postretirement Benefit Plans, Defined Benefit
Change in Benefit Obligation
Benefit obligation at beginning of year	(1,179)	(1,145)
Service cost	(12)	(13)
Interest cost	(59)	(62)
Amendments	0	(3)
Actuarial loss	(211)	(40)
Settlement/curtailment/other	(5)	3
Benefits paid	82	81
Benefit obligation at end of year	(1,384)	(1,179)
Change in Plan/Trust Assets [Member] | Pension Benefits
Change in Plan/Trust Assets
Fair value of assets at beginning of year	6,250	6,250
Actual return on plan assets	874	80
Employer contributions	532	351
Settlement/curtailment/other	12	4
Benefits paid	(441)	(435)
Fair value of assets at end of year	7,227	6,250
Funded status at end of year	(4,887)	(3,992)
Change in Plan/Trust Assets [Member] | Other Postretirement Benefit Plans, Defined Benefit
Change in Plan/Trust Assets
Fair value of assets at beginning of year	379	389
Actual return on plan assets	64	10
Employer contributions	32	31
Settlement/curtailment/other	0	0
Benefits paid	(49)	(51)
Fair value of assets at end of year	426	379
Funded status at end of year	$ (958)	$ (800)