Pension and Other Postretirement Benefit Plans (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Plans, Defined Benefit [Member]
Components of net cost of defined benefit plans
Service cost	$ 151	$ 147	$ 303	$ 301
Interest cost	180	172	359	349
Expected return on plan assets	(242)	(215)	(485)	(432)
Net amortization	46	43	91	88
Termination benefits	7	9	17	28
Curtailments	(6)	(1)	(10)	(37)
Settlements	0	(6)	(1)	(7)
Net cost	136	149	274	290
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of net cost of defined benefit plans
Service cost	28	28	56	54
Interest cost	35	36	71	74
Expected return on plan assets	(36)	(33)	(71)	(65)
Net amortization	(6)	2	(9)	4
Termination benefits	4	7	6	27
Curtailments	0	(2)	1	(2)
Net cost	$ 25	$ 38	$ 54	$ 92