Ownership of Coal-fired Facilities (Ownership Interests) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 MW
Construction Work in Process	$ 23.0
DP&L [Member]
Construction Work in Process	23.0
DP&L Share [Member] | Beckjord Unit 6 [Member]
Ownership (%)	50.00%
Production Capacity (MW)	207
DP&L Share [Member] | Conesville Unit 4 [Member]
Ownership (%)	16.50%
Production Capacity (MW)	129
DP&L Share [Member] | East Bend Station [Member]
Ownership (%)	31.00%
Production Capacity (MW)	186
DP&L Share [Member] | Killen Station [Member]
Ownership (%)	67.00%
Production Capacity (MW)	402
DP&L Share [Member] | Miami Fort Units 7 and 8 [Member]
Ownership (%)	36.00%
Production Capacity (MW)	368
DP&L Share [Member] | Stuart Station [Member]
Ownership (%)	35.00%
Production Capacity (MW)	808
DP&L Share [Member] | Zimmer Station [Member]
Ownership (%)	28.10%
Production Capacity (MW)	365
DP&L Share [Member] | Total Jointly-owned Stations [Member]
Production Capacity (MW)	2,465
DP&L Share [Member] | Hutchings Station [Member]
Ownership (%)	100.00%
Production Capacity (MW)	302
DP&L Share [Member] | DP&L [Member] | Beckjord Unit 6 [Member]
Ownership (%)	50.00%
Production Capacity (MW)	207
DP&L Share [Member] | DP&L [Member] | Conesville Unit 4 [Member]
Ownership (%)	16.50%
Production Capacity (MW)	129
DP&L Share [Member] | DP&L [Member] | East Bend Station [Member]
Ownership (%)	31.00%
Production Capacity (MW)	186
DP&L Share [Member] | DP&L [Member] | Killen Station [Member]
Ownership (%)	67.00%
Production Capacity (MW)	402
DP&L Share [Member] | DP&L [Member] | Miami Fort Units 7 and 8 [Member]
Ownership (%)	36.00%
Production Capacity (MW)	368
DP&L Share [Member] | DP&L [Member] | Stuart Station [Member]
Ownership (%)	35.00%
Production Capacity (MW)	808
DP&L Share [Member] | DP&L [Member] | Zimmer Station [Member]
Ownership (%)	28.10%
Production Capacity (MW)	365
DP&L Share [Member] | DP&L [Member] | Total Jointly-owned Stations [Member]
Production Capacity (MW)	2,465
DP&L Share [Member] | DP&L [Member] | Hutchings Station [Member]
Ownership (%)	100.00%
Production Capacity (MW)	302
DP&L Investment [Member] | Beckjord Unit 6 [Member]
Gross Plant In Service	1.0
Accumulated Depreciation	1.0
SCR and FGD Equipment Installed and In Service	No
DP&L Investment [Member] | Conesville Unit 4 [Member]
Gross Plant In Service	47.0
Accumulated Depreciation	1.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | East Bend Station [Member]
Gross Plant In Service	10.0
Accumulated Depreciation	4.0
Construction Work in Process	3.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Killen Station [Member]
Gross Plant In Service	311.0
Accumulated Depreciation	8.0
Construction Work in Process	4.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Miami Fort Units 7 and 8 [Member]
Gross Plant In Service	211.0
Accumulated Depreciation	8.0
Construction Work in Process	1.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Stuart Station [Member]
Gross Plant In Service	204.0
Accumulated Depreciation	10.0
Construction Work in Process	12.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Zimmer Station [Member]
Gross Plant In Service	172.0
Accumulated Depreciation	19.0
Construction Work in Process	3.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Total Jointly-owned Stations [Member]
Gross Plant In Service	996.0
Accumulated Depreciation	54.0
Construction Work in Process	23.0
DP&L Investment [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	40.0
Accumulated Depreciation	3.0
DP&L Investment [Member] | Hutchings Station [Member]
SCR and FGD Equipment Installed and In Service	No
DP&L Investment [Member] | DP&L [Member] | Beckjord Unit 6 [Member]
Gross Plant In Service	76.0
Accumulated Depreciation	66.0
SCR and FGD Equipment Installed and In Service	No
DP&L Investment [Member] | DP&L [Member] | Conesville Unit 4 [Member]
Gross Plant In Service	31.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | East Bend Station [Member]
Gross Plant In Service	210.0
Accumulated Depreciation	138.0
Construction Work in Process	3.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Killen Station [Member]
Gross Plant In Service	626.0
Accumulated Depreciation	305.0
Construction Work in Process	4.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Miami Fort Units 7 and 8 [Member]
Gross Plant In Service	360.0
Accumulated Depreciation	147.0
Construction Work in Process	1.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Stuart Station [Member]
Gross Plant In Service	744.0
Accumulated Depreciation	301.0
Construction Work in Process	12.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Zimmer Station [Member]
Gross Plant In Service	1,096.0
Accumulated Depreciation	648.0
Construction Work in Process	3.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Total Jointly-owned Stations [Member]
Gross Plant In Service	3,240.0
Accumulated Depreciation	1,665.0
Construction Work in Process	23.0
DP&L Investment [Member] | DP&L [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	97.0
Accumulated Depreciation	$ 60.0
DP&L Investment [Member] | DP&L [Member] | Hutchings Station [Member]
SCR and FGD Equipment Installed and In Service	No