Pension Plans, Retirement Benefits and Savings Plans (details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 28	$ 25
Interest cost on benefit obligation	35	34
Expected return on plan assets	(47)	(46)
Amortization of unrecognized net actuarial loss	22	19
Net periodic benefit cost, net benefit expense	38	32
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	3	3
Net periodic benefit cost, net benefit expense	$ 3	$ 3