XML 42 R52.htm IDEA: XBRL DOCUMENT v2.4.1.9
Ownership of Coal-fired Facilities (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended 3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2012
Dec. 31, 2013
Construction work in process $ 25.0us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress    
Number Of Generating Facilities 5dpl_NumberOfGeneratingFacilities    
DP&L [Member]      
Undivided ownership interests 5.00%dpl_UndividedOwnershipInterests
/ dei_LegalEntityAxis
= dpl_DpLMember		    
Construction work in process 25.0us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
/ dei_LegalEntityAxis
= dpl_DpLMember		    
Conesville [Member] | DP&L [Member]      
Impairment of Long-Lived Assets Held-for-use   80.8us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ invest_InvestmentAxis
= dpl_ConesvilleUnitFourMember
/ dei_LegalEntityAxis
= dpl_DpLMember		  
East Bend Station [Member] | DP&L [Member]      
Impairment of Long-Lived Assets Held-for-use     $ 86.0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ invest_InvestmentAxis
= dpl_EastBendStationMember
/ dei_LegalEntityAxis
= dpl_DpLMember