Employee Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets
Projected benefit obligations	$ 9,480	$ 8,327
Fair value of plan assets	7,879	7,108
Foreign Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets
Projected benefit obligations	763	732
Fair value of plan assets	188	140
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets
Projected benefit obligations	2,375	2,093
Fair value of plan assets	1,320	1,240
Foreign Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets
Projected benefit obligations	43	39
Fair value of plan assets	$ 15	$ 13