Benefit Plans Benefit Plans (Movements in Other Comprehensive Earnings/Losses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	$ 281	$ 226	$ 170
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(35)	(7)	(8)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Other Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	21
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, Other Expense (Income) before Tax	(26)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(815)	(900)	(146)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax		266	42
Other Comprehensive Income Defined Benefit Plan Net Deferred Income Tax Arising During Period	(93)	(85)	(63)
Other Comprehensice Income (Loss), Pension and Other Postretirement Benefit Plans, Reclassification Adjustment Net Gains (Losses) and Prior Service Cost (Credit), Net of Tax	148	134	99
Other Comprehensive Income Defined Benefit Plan Net Other Deferred Income Taxes Arising During Period	315	249	40
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(500)	(385)	(64)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(352)	(251)	35
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	224	171	126
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	10	14	13
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Other Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	21
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, Other Expense (Income) before Tax	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(643)	(672)	(41)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax		2	(16)
Other Comprehensive Income Defined Benefit Plan Net Deferred Income Tax Arising During Period	(99)	(72)	(55)
Other Comprehensice Income (Loss), Pension and Other Postretirement Benefit Plans, Reclassification Adjustment Net Gains (Losses) and Prior Service Cost (Credit), Net of Tax	156	113	84
Other Comprehensive Income Defined Benefit Plan Net Other Deferred Income Taxes Arising During Period	249	262	21
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(394)	(408)	(36)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(238)	(295)	48
Post-Retirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	40	39	32
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(45)	(21)	(21)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Other Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, Other Expense (Income) before Tax	(26)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(161)	(188)	(95)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax		264	58
Other Comprehensive Income Defined Benefit Plan Net Deferred Income Tax Arising During Period	12	(7)	(4)
Other Comprehensice Income (Loss), Pension and Other Postretirement Benefit Plans, Reclassification Adjustment Net Gains (Losses) and Prior Service Cost (Credit), Net of Tax	(19)	11	7
Other Comprehensive Income Defined Benefit Plan Net Other Deferred Income Taxes Arising During Period	63	(27)	15
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(98)	49	(22)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(117)	60	(15)
Post-Employment [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	17	16	12
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	0	0	0
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Other Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, Other Expense (Income) before Tax	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(11)	(40)	(10)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax		0	0
Other Comprehensive Income Defined Benefit Plan Net Deferred Income Tax Arising During Period	(6)	(6)	(4)
Other Comprehensice Income (Loss), Pension and Other Postretirement Benefit Plans, Reclassification Adjustment Net Gains (Losses) and Prior Service Cost (Credit), Net of Tax	11	10	8
Other Comprehensive Income Defined Benefit Plan Net Other Deferred Income Taxes Arising During Period	3	14	4
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(8)	(26)	(6)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ 3	$ (16)	$ 2