Regulatory Matters (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Regulatory Assets	$ 180.5	$ 206.6
Regulatory Liabilities	121.1	117.4
Fuel and purchased power recovery costs [Member]
Disallowance of regulatory asset	5.3
DP&L [Member]
Regulatory Assets	180.5	203.8
Regulatory Liabilities	121.1	117.4
DP&L [Member] | Fuel and purchased power recovery costs [Member]
Disallowance of regulatory asset	$ 5.3