Retirement Benefits and Trusteed Assets Retirement Benefits and Trusteed Assets Textuals (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 240
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	120
Defined Benefit Plan, Contributions by Employer	$ 140