Retirement Benefits and Trusteed Assets Retirement Benefits and Trusteed Assets (Details 13) (Other Postretirement Benefit Plans, Defined Benefit [Member])	12 Months Ended
	Dec. 31, 2011 percent
Other Postretirement Benefits Target Allocations of Plan Assets [Line Items]
Defined Benefit Plan, Target Allocation Percentage of Assets, Debt Securities	25.00%
Defined Benefit Plan Target Allocation Percentage of Assets Hedged Funds and Similar Investments	20.00%
Defined Benefit Plan, Target Allocation Percentage of Assets, Other	13.00%
Defined Benefit Plan Target Allocation Percentage of Assets Total	100.00%
Us Large Cap Equity Securities [Member]
Other Postretirement Benefits Target Allocations of Plan Assets [Line Items]
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	22.00%
Non US Equity Securities [Member]
Other Postretirement Benefits Target Allocations of Plan Assets [Line Items]
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	20.00%