Pension Plans, Retirement Benefits and Savings Plans (details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 30	$ 29	$ 59	$ 57
Interest cost on benefit obligation	33	34	66	69
Expected return on plan assets	(52)	(47)	(104)	(94)
Amortization of unrecognized net actuarial loss	26	23	53	45
Net periodic benefit cost, net benefit expense	37	39	74	77
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	2	3	4	6
Expected return on plan assets		(1)		(1)
Amortization of unrecognized prior service benefit	(1)		(1)
Net periodic benefit cost, net benefit expense	$ 1	$ 2	$ 3	$ 5