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Ownership of Coal-fired Facilities (Narrative) (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Construction work in process $ 24,000,000us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress  
Number Of Generating Facilities 5dpl_NumberOfGeneratingFacilities  
Impairment of Long-Lived Assets Held-for-use   11,500,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
DP&L [Member]    
Construction work in process $ 24,000,000us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
/ dei_LegalEntityAxis
= dpl_DpLMember
 
Number Of Generating Facilities 5dpl_NumberOfGeneratingFacilities
/ dei_LegalEntityAxis
= dpl_DpLMember