Pensions and Other Postemployment Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pensions
Components of Net Periodic Benefit Costs (Credits)
Service cost	$ 40	$ 34	$ 120	$ 97
Interest cost	97	96	291	276
Expected return on plan assets	(121)	(115)	(363)	(332)
Amortization of prior service cost	3	4	9	12
Other adjustments (settlements, curtailments, etc)			0	7
Net periodic costs (credits)	19	19	57	60
OPEB
Components of Net Periodic Benefit Costs (Credits)
Service cost	3	3	9	9
Interest cost	12	12	36	35
Expected return on plan assets	(9)	(10)	(27)	(30)
Amortization of prior service cost	(51)	(51)	(153)	(150)
Other adjustments (settlements, curtailments, etc)			0	0
Net periodic costs (credits)	$ (45)	$ (46)	$ (135)	$ (136)