Pension Plans, Retirement Benefits and Savings Plans (details) (USD $) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012	Aug. 31, 2011	Sep. 30, 2012 Pension Plans [Member]	Sep. 30, 2011 Pension Plans [Member]	Sep. 30, 2012 Pension Plans [Member]	Sep. 30, 2011 Pension Plans [Member]	Sep. 30, 2012 Postretirement Benefit Plans [Member]	Sep. 30, 2011 Postretirement Benefit Plans [Member]	Sep. 30, 2012 Postretirement Benefit Plans [Member]	Sep. 30, 2011 Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Service cost			$ 28	$ 25	$ 85	$ 74		$ 1		$ 1
Interest cost on benefit obligation			34	33	103	101	3	3	9	10
Expected return on plan assets			(46)	(46)	(140)	(137)			(1)	(1)
Amortization of unrecognized net actuarial loss			22	20	67	58
Net periodic benefit cost, net benefit expense			38	32	115	96	3	4	8	10
Company contribution to qualified domestic pension plan	$ 67	$ 35