Pension and Postretirement Benefits (Weighted Average Assumptions Used to Determine Benefit Obligations) (Details)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.04%	4.88%	5.31%
Rate of compensation increases	3.94%	3.94%	3.94%
Pension [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.04%	4.88%	5.31%
Rate of compensation increases	3.94%	3.94%	3.94%
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	3.75%	4.62%	4.96%
Postretirement [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	3.75%	4.62%	4.96%