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Pension and Postretirement Health and Life Benefits (Schedule of Assumptions Used) (Details)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Defined Benefit Pension Plans [Member]
     
Discount rate 5.77% 5.84% 6.09%
Expected return on plan assets 7.50% 7.50% 7.75%
Compensation increases 4.25% 4.25% 4.25%
Postretirement Health and Life Benefits Plans [Member]
     
Discount rate 5.32% 5.44% 6.00%
Expected return on plan assets 7.50% 7.50% 7.50%
Compensation increases 4.25% 4.25% 4.25%