Employee Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 0	$ 0	$ 0
Defined Benefit Plan, Interest Cost	930	969	982
Defined Benefit Plan, Expected Return on Plan Assets	(705)	(724)	(677)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Defined Benefit Plan, Amortization of Gains (Losses)	143	55	48
Defined Benefit Plan, Recognized Net (Gain) Loss Due to Settlements	0	0	14
Defined Benefit Plan, Other Costs	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	368	300	367
Defined Contribution Plan, Cost Recognized	426	377	334
Defined Benefit Plan Cost Benefit	794	677	701
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	56	52	58
Defined Benefit Plan, Interest Cost	164	180	196
Defined Benefit Plan, Expected Return on Plan Assets	(77)	(90)	(90)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(21)	(3)	(4)
Defined Benefit Plan, Amortization of Gains (Losses)	23	(11)	(4)
Defined Benefit Plan, Recognized Net (Gain) Loss Due to Settlements	0	0	0
Defined Benefit Plan, Other Costs	116	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	261	128	156
Defined Contribution Plan, Cost Recognized	0	0	0
Defined Benefit Plan Cost Benefit	$ 261	$ 128	$ 156