Pension Plans, Retirement Benefits and Savings Plans (details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 29	$ 24	$ 57	$ 49
Interest cost on benefit obligation	34	34	69	68
Expected return on plan assets	(47)	(45)	(94)	(91)
Amortization of unrecognized net actuarial loss	23	19	45	38
Net periodic benefit cost, net benefit expense	39	32	77	64
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	3	4	6	7
Expected return on plan assets	(1)	(1)	(1)	(1)
Net periodic benefit cost, net benefit expense	$ 2	$ 3	$ 5	$ 6