XML 41 R30.htm IDEA: XBRL DOCUMENT v2.4.1.9
Summary of Significant Accounting Policies (Narrative) (Details) (USD $)
 3 Months Ended 0 Months Ended 12 Months Ended
Mar. 31, 2015
sqmi
employee
Apr. 01, 2015
Dec. 31, 2015
Service Area Square Miles 6,000dpl_ServiceAreaSquareMiles    
Approximate number of retail customers 516,000dpl_NumberOfRetailCustomers    
Approximate number of DPLER customers 259,000dpl_ApproximateNumberOfDplerCustomers    
Entity number of employees 1,185dei_EntityNumberOfEmployees    
Number of coal fired power plants 5dpl_NumberOfCoalFiredPowerPlants    
Employees under a collective bargaining agreement which expires in October-2011 60.00%dpl_PercentageOfEmployeesUnderCollectiveBargainingAgreement    
Subsequent Event [Member]      
Approximate number of DPLER customers after MC squared sale   $ 143,000dpl_ApproximateNumberOfDplerCustomersAfterMcSquaredSale
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		  
DP&L [Member]      
Service Area Square Miles 6,000dpl_ServiceAreaSquareMiles
/ dei_LegalEntityAxis
= dpl_DpLMember		    
Approximate number of retail customers 516,000dpl_NumberOfRetailCustomers
/ dei_LegalEntityAxis
= dpl_DpLMember		    
Entity number of employees 1,166dei_EntityNumberOfEmployees
/ dei_LegalEntityAxis
= dpl_DpLMember		    
Employees under a collective bargaining agreement which expires in October-2011 61.00%dpl_PercentageOfEmployeesUnderCollectiveBargainingAgreement
/ dei_LegalEntityAxis
= dpl_DpLMember		    
MC Squared [Member]      
Approximate number of DPLER customers 116,000dpl_ApproximateNumberOfDplerCustomers
/ dei_LegalEntityAxis
= dpl_McSquaredMember		    
Year 2015 [Member]      
Electric generation through competitive bid 60.00%dpl_ElectricGenerationThroughCompetitiveBid
/ dpl_PhaseInTimePeriodAxis
= dpl_Year2015Member		    
Year 2015 [Member] | DP&L [Member]      
Electric generation through competitive bid 60.00%dpl_ElectricGenerationThroughCompetitiveBid
/ dei_LegalEntityAxis
= dpl_DpLMember
/ dpl_PhaseInTimePeriodAxis
= dpl_Year2015Member		    
Year 2016 [Member] | Scenario, Forecast [Member]      
Electric generation through competitive bid 100.00%dpl_ElectricGenerationThroughCompetitiveBid
/ dpl_PhaseInTimePeriodAxis
= dpl_Year2016Member
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember		   100.00%dpl_ElectricGenerationThroughCompetitiveBid
/ dpl_PhaseInTimePeriodAxis
= dpl_Year2016Member
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember