Commitments, Environmental, Legal (Schedule Of Contractual Obligations And Commercial Commitments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Contractual Obligations, Commercial Commitments And Contingencies [Line Items]
Total long-term debt	$ 2,025.0	$ 2,025.0
Long-term debt, Less than 1 year	570.4
Long-term debt, More than 5 years	1,152.8
DP&L [Member]
Contractual Obligations, Commercial Commitments And Contingencies [Line Items]
Total long-term debt	332.7	332.7
Long-term debt, Less than 1 year	570.4
Long-term debt, More than 5 years	$ 332.3