Property, Plant and Equipment (Ownership Interests) (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) MW
Conesville [Member]
Ownership (%)	16.50%
Production Plan Capacity \| MW	129
Gross Plant In Service	$ 1
Accumulated Depreciation	1
Construction Work in Process	$ 2
Killen Station [Member]
Ownership (%)	67.00%
Production Plan Capacity \| MW	402
Gross Plant In Service	$ 10
Accumulated Depreciation	8
Construction Work in Process	$ 0
Stuart Station - Units 2-4 [Member]
Ownership (%)	35.00%
Stuart Station [Member]
Production Plan Capacity \| MW	606
Gross Plant In Service	$ 2
Accumulated Depreciation	2
Construction Work in Process	0
Electric Transmission [Member]
Gross Plant In Service	46
Accumulated Depreciation	13
Construction Work in Process	$ 0
Total Jointly Owned Stations [Member]
Production Plan Capacity \| MW	1,137
Gross Plant In Service	$ 58
Accumulated Depreciation	24
Construction Work in Process	$ 2

Production Plan Capacity

No definition available.

Name:	dpl_ProductionPlanCapacity
Namespace Prefix:	dpl_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033

+ Details

Name:	us-gaap_JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

+ References

+ Details

Name:	us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

+ References

+ Details

Name:	us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

+ Details

Name:	us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dpl_ConesvilleUnitFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dpl_KillenStationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dpl_StuartStationUnits24Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dpl_StuartStationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ElectricTransmissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dpl_TotalJointlyOwnedStationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: