Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets period End	$ 8,714	$ 9,359
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation Period Start	17,506	17,031
Defined Benefit Plan, Service Cost	0	0	0
Defined Benefit Plan, Interest Cost	969	982	1,002
Defined Benefit Plan, Actuarial Net (Gains) Losses	1,860	570
Defined Benefit Plan, Benefits Paid	(1,042)	(1,013)
Defined Benefit Plan, Contributions by Plan Participants	0	0
Defined Benefit Plan, Plan Amendments	0	0
Defined Benefit Plan, Special Termination Benefits	0	0
Defined Benefit Plan, Settlements, Benefit Obligation	0	(64)
Defined Benefit Plan, Benefit Obligation Period End	19,293	17,506	17,031
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets Period Start	8,249	7,623
Defined Benefit Plan, Actual Return on Plan Assets	(16)	975
Defined Benefit Plan, Contributions by Employer	598	728
Defined Benefit Plan, Contributions by Plan Participants	0	0
Defined Benefit Plan, Benefits Paid	1,042	1,013
Defined Benefit Plan, Settlements, Plan Assets	0	(64)
Defined Benefit Plan, Fair Value of Plan Assets period End	7,789	8,249	7,623
Defined Benefit Plan, Funded Status of Plan [Abstract]
Defined Benefit Plan, Funded Status of Plan	(11,504)	(9,257)
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation Period Start	3,298	3,427
Defined Benefit Plan, Service Cost	52	58	53
Defined Benefit Plan, Interest Cost	180	196	207
Defined Benefit Plan, Actuarial Net (Gains) Losses	311	(115)
Defined Benefit Plan, Benefits Paid	(328)	(333)
Defined Benefit Plan, Contributions by Plan Participants	54	59
Defined Benefit Plan, Plan Amendments	0	6
Defined Benefit Plan, Special Termination Benefits	3	0
Defined Benefit Plan, Settlements, Benefit Obligation	0	0
Defined Benefit Plan, Benefit Obligation Period End	3,570	3,298	3,427
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets Period Start	1,120	1,153
Defined Benefit Plan, Actual Return on Plan Assets	(37)	140
Defined Benefit Plan, Contributions by Employer	235	171
Defined Benefit Plan, Contributions by Plan Participants	54	59
Defined Benefit Plan, Benefits Paid	328	333
Defined Benefit Plan, Fair Value of Plan Assets, Period Increase (Decrease)	(400)	(403)
Defined Benefit Plan, Settlements, Plan Assets	0	0
Defined Benefit Plan, Fair Value of Plan Assets period End	972	1,120	1,153
Defined Benefit Plan, Funded Status of Plan [Abstract]
Defined Benefit Plan, Funded Status of Plan	$ (2,598)	$ (2,178)