Employee 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 Benefits [Member]
Components of net periodic benefit costs
Service costs	$ 64	$ 45	$ 190	$ 133
Interest costs	104	99	314	298
Expected return on plan assets	(112)	(113)	(339)	(337)
Settlement and curtailment costs	0	1	0	8
Amortization of net actuarial (gains) losses	49	49	146	147
Amortization of prior service costs (credit)	1	2	3	5
Net periodic benefit costs	106	83	314	254
Other Postretirement Benefits [Member]
Components of net periodic benefit costs
Service costs	4	4	13	13
Interest costs	27	28	81	84
Expected return on plan assets	(19)	(19)	(58)	(59)
Settlement and curtailment costs	0	0	0	0
Amortization of net actuarial (gains) losses	11	9	32	28
Amortization of prior service costs (credit)	(27)	(21)	(81)	(62)
Net periodic benefit costs	$ (4)	$ 1	$ (13)	$ 4