Retirement Benefits and Trusteed Assets (OPEB - Target Allocations of Plan Assets) (Details) (Other Postretirement Benefit Plan)	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	100.00%
US Large Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	17.00%
US Small Cap and Mid Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	4.00%
Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	25.00%
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	14.00%