Benefit Plans (Changes In Accumulated Postretirement Benefit Obligation) (Details) (Post-Retirement [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Post-Retirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	$ 2,505	$ 2,548
Service cost	18	34	29
Interest cost	115	139	135
Benefits paid	(135)	(136)
Plan amendments	0	(282)
Actuarial losses/(gains)	160	191
Terminations and curtailments	0	(11)
Benefit obligation at end of year	$ 2,663	$ 2,505	$ 2,548