Retirement Benefits and Trusteed Assets (OPEB - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) (Other Postretirement Benefit Plan, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Other Postretirement Benefit Plan, Defined Benefit [Member]
Benefits Expected to be Paid Over the Next Five Years and Thereafter [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments in next twelve months	$ 103
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	110
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	115
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	123
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	130
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	724
Total Expected Future Benefit Payments	$ 1,305