Fixed-asset Impairment (Narrative) (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2012 DP&L [Member]	Dec. 31, 2013 Conesville Unit 4 [Member] MW	Dec. 31, 2013 Conesville Unit 4 [Member] DP&L [Member] MW	Dec. 31, 2012 Conesville Unit 4 [Member] DP&L [Member]	Dec. 31, 2013 East Bend Station [Member] DP&L [Member] MW	Dec. 31, 2012 Hutchings Plant [Member] DP&L [Member]
Fair Value				$ 0	$ 0	$ 25.0		$ 0
Carrying Value	2,534.2	2,563.8		26.2	30.0	97.5	76.0	8.3
Fixed asset impairment			$ 80.8	$ 26.2	$ 10.0	$ 72.5	$ 76.0	$ 8.3
Production Plan Capacity				129	129		186