Benefit Plans (Amounts Recorded In Accumulated Other Comprehensive Losses) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	$ (4,272)	$ (3,759)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	318	379
Deferred Tax Liabilities, Other Comprehensive Income	1,540	1,318
Amounts recorded in accumulated other comprehensive losses	(2,414)	(2,062)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(3,186)	(2,788)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(36)	(46)
Deferred Tax Liabilities, Other Comprehensive Income	1,254	1,104
Amounts recorded in accumulated other comprehensive losses	(1,968)	(1,730)
Post-Retirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(917)	(796)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	354	425
Deferred Tax Liabilities, Other Comprehensive Income	221	146
Amounts recorded in accumulated other comprehensive losses	(342)	(225)
Post-Employment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(169)	(175)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	0	0
Deferred Tax Liabilities, Other Comprehensive Income	65	68
Amounts recorded in accumulated other comprehensive losses	$ (104)	$ (107)