Pensions and Other Postemployment Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pensions
Components of Net Periodic Benefit Costs (Credits)
Service cost	$ 40	$ 29
Interest cost	97	84
Expected return on plan assets	(121)	(102)
Amortization of prior service cost	3	4
Other adjustments (settlements, curtailments, etc)	0	7
Net periodic cost (credit)	19	22
OPEB
Components of Net Periodic Benefit Costs (Credits)
Service cost	3	3
Interest cost	12	11
Expected return on plan assets	(9)	(10)
Amortization of prior service cost	(51)	(48)
Other adjustments (settlements, curtailments, etc)	0	0
Net periodic cost (credit)	$ (45)	$ (44)