Pension Plans, Retirement Benefits and Savings Plans (details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plans [Member]
Defined benefit plan disclosure
Service cost	$ 30	$ 28	$ 89	$ 85
Interest cost on benefit obligation	33	34	99	103
Expected return on plan assets	(52)	(46)	(156)	(140)
Amortization of unrecognized net actuarial loss	27	22	80	67
Net periodic benefit cost, net benefit expense	38	38	112	115
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Interest cost on benefit obligation	3	3	7	9
Expected return on plan assets				(1)
Amortization of unrecognized prior service benefit	(1)		(2)
Net periodic benefit cost, net benefit expense	$ 2	$ 3	$ 5	$ 8