Pension and Other Postretirement Benefit Plans (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Plans, Defined Benefit [Member]
Components of net cost of defined benefit plans
Service cost	$ 158	$ 125	$ 461	$ 426
Interest cost	182	158	541	507
Expected return on plan assets	(243)	(225)	(728)	(657)
Net amortization	58	22	149	110
Termination benefits	15	14	32	42
Curtailments	(6)	(3)	(16)	(40)
Settlements			(1)	(7)
Net cost	164	91	438	381
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of net cost of defined benefit plans
Service cost	27	27	83	81
Interest cost	35	37	106	111
Expected return on plan assets	(35)	(32)	(106)	(97)
Net amortization	(4)	1	(13)	5
Termination benefits	5	9	11	36
Curtailments	(1)	1		(1)
Net cost	$ 27	$ 43	$ 81	$ 135