Postretirement Plans (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Increase in net periodic cost due to cumulative effect of adjustment	$ 23		$ 23
Increase Due To Adjustment [Member] | Other Postretirement Benefit Plans [Member]
Service cost	73		73
Interest cost	68		68
Recognized net actuarial loss	43		43
Net periodic benefit cost	184		184
Net periodic benefit cost included in Earnings from operations	161		161
Additional post retirement benefit obligation	294		294		274
Increase To Liability Due To Adjustment [Member] | Other Postretirement Benefit Plans [Member]
Additional post retirement benefit obligation					8,820
Pension Plans [Member]
Service cost	351	294	1,053	881
Interest cost	780	751	2,339	2,252
Expected return on plan assets	(935)	(963)	(2,805)	(2,887)
Amortization of prior service costs	61	62	182	186
Recognized net actuarial loss	314	194	942	582
Settlement and curtailment loss	9		64	11
Net periodic benefit cost	580	338	1,775	1,025
Net periodic benefit cost included in Earnings from operations	389	280	1,304	847
Contributions to plans			500	13
Other Postretirement Benefit Plans [Member]
Service cost	110	30	182	90
Interest cost	171	101	377	303
Expected return on plan assets	(2)	(1)	(4)	(4)
Amortization of prior service costs	(24)	(19)	(72)	(58)
Recognized net actuarial loss	76	14	142	42
Settlement and curtailment loss				32
Net periodic benefit cost	331	125	625	405
Net periodic benefit cost included in Earnings from operations	281	124	561	376
Additional post retirement benefit obligation					8,546
Contributions to plans			$ 12	$ 11