Retirement Benefits and Trusteed Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	$ 55	$ 42
Defined Benefit Plan, Service Cost	21	19
Defined Benefit Plan, Interest Cost	51	51
Defined Benefit Plan, Expected Return on Plan Assets	(61)	(62)
Defined Benefit Plan, Amortization of Net Gains (Losses)	42	33
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	1
Defined Benefit Plan Net Transition Liability	0	0
Defined Benefit Plan, Special Termination Benefits	2	0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	38	33
Defined Benefit Plan, Service Cost	18	17
Defined Benefit Plan, Interest Cost	30	31
Defined Benefit Plan, Expected Return on Plan Assets	(23)	(24)
Defined Benefit Plan, Amortization of Net Gains (Losses)	19	15
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(7)	(7)
Defined Benefit Plan Net Transition Liability	1	1
Defined Benefit Plan, Special Termination Benefits	$ 0	$ 0