Derivative Instruments and Hedging Activities (Outstanding Derivative Instruments) (Details)	3 Months Ended	12 Months Ended
Mar. 31, 2015 MWh	Dec. 31, 2014 MWh
DP&L [Member] \| Natural Gas [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure		200,000
Designated as Hedging Instrument [Member] \| Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	843,500	175,000
Sales of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	(3,708,300)	(2,991,000)
Derivative, Nonmonetary Notional Amount MWh	(2,864,800)	(2,816,000)
Designated as Hedging Instrument [Member] \| DP&L [Member] \| Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	843,500	175,000
Sales of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	(3,708,300)	(2,991,000)
Derivative, Nonmonetary Notional Amount MWh	(2,864,800)	(2,816,000)
Not Designated as Hedging Instrument [Member] \| Commodity Contract - FTR [Member]
Purchase of Units Derivative Instruments Financial Transmission Rights	4,200	10,500
Derivative, Nonmonetary Notional Amount MWh	4,200	10,500
Not Designated as Hedging Instrument [Member] \| Commodity Contract - Heating Oil [Member]
Purchase of Volume Units Derivative Instruments Heating Oil Futures	252,000	378,000
Derivative, Nonmonetary Notional Amount, Volume	252,000	378,000
Not Designated as Hedging Instrument [Member] \| Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	1,565,100	1,725,200
Sales of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	(4,826,900)	(2,707,800)
Derivative, Nonmonetary Notional Amount MWh	(3,261,800)	(982,600)
Not Designated as Hedging Instrument [Member] \| Natural Gas [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure		200,000
Not Designated as Hedging Instrument [Member] \| DP&L [Member] \| Commodity Contract - FTR [Member]
Purchase of Units Derivative Instruments Financial Transmission Rights	4,200	10,500
Derivative, Nonmonetary Notional Amount MWh	4,200	10,500
Not Designated as Hedging Instrument [Member] \| DP&L [Member] \| Commodity Contract - Heating Oil [Member]
Purchase of Volume Units Derivative Instruments Heating Oil Futures	252,000	378,000
Derivative, Nonmonetary Notional Amount, Volume	252,000	378,000
Not Designated as Hedging Instrument [Member] \| DP&L [Member] \| Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	1,565,100	1,725,200
Sales of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	(4,911,800)	(2,804,000)
Derivative, Nonmonetary Notional Amount MWh	(3,346,700)	(1,078,800)

Net non-monetary notional amount of commodities measured in MWh

No definition available.

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Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate notional amount of contracts to purchase financial transmission rights

+ References

No definition available.

+ Details

Name:	dpl_PurchaseOfUnitsDerivativeInstrumentsFinancialTransmissionRights
Namespace Prefix:	dpl_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate notional amount of contracts to purchase forward power designated as cash flow hedges.

+ References

No definition available.

+ Details

Name:	dpl_PurchaseOfUnitsDerivativeInstrumentsForwardPowerContractsDesignatedAsCashFlowHedge
Namespace Prefix:	dpl_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate notional amount of contracts to purchase forward power not designated as hedged.

+ References

No definition available.

+ Details

Name:	dpl_PurchaseOfUnitsDerivativeInstrumentsForwardPowerContractsNotDesignatedAsHedged
Namespace Prefix:	dpl_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate notional amount of contracts to purchase heating oil futures.

+ References

No definition available.

+ Details

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Namespace Prefix:	dpl_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate notional amount of contracts to sell forward power designated as cash flow hedges.

+ References

No definition available.

+ Details

Name:	dpl_SalesOfUnitsDerivativeInstrumentsForwardPowerContractsDesignatedAsCashFlowHedge
Namespace Prefix:	dpl_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate notional amount of contracts to sell forward power not designated as hedged.

+ References

No definition available.

+ Details

Name:	dpl_SalesOfUnitsDerivativeInstrumentsForwardPowerContractsNotDesignatedAsHedged
Namespace Prefix:	dpl_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal volume used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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