Retirement Benefits and Trusteed Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	$ 24	$ 21
Defined Benefit Plan, Interest Cost	48	51
Defined Benefit Plan, Expected Return on Plan Assets	(67)	(61)
Defined Benefit Plan, Amortization of Net Gains (Losses)	51	42
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0
Defined Benefit Plan Net Transition Liability	0	0
Defined Benefit Plan, Special Termination Benefits	0	2
Defined Benefit Plan, Net Periodic Benefit Cost	56	55
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	16	18
Defined Benefit Plan, Interest Cost	24	30
Defined Benefit Plan, Expected Return on Plan Assets	(27)	(23)
Defined Benefit Plan, Amortization of Net Gains (Losses)	17	19
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(23)	(7)
Defined Benefit Plan Net Transition Liability	0	1
Defined Benefit Plan, Special Termination Benefits	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ 7	$ 38