Employee Benefit Plans (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	$ (14,200)	$ (11,493)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	6,300	3,300
United States Pension Plans of US Entity, Defined Benefit [Member]
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(16)	(13)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(11,488)	(9,244)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(11,504)	(9,257)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	5,844	3,299
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	0	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	(5,844)	(3,299)
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(137)	(144)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(2,460)	(2,034)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(2,597)	(2,178)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	406	(44)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(5)	(3)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	$ (411)	$ 41