Retirement Benefits and Trusteed Assets Retirement Benefits and Trusteed Assets (OPEB - Future Payments) (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Other Postretirement Benefit Plans, Defined Benefit [Member]
Benefits Expected to be Paid Over the Next Five Years and Thereafter [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	$ 78
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	83
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	87
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	93
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	98
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	555
Total Expected Future Benefit Payments	$ 994