Ownership of Coal-fired Facilities (Ownership Interests) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 MW
Construction Work in Process	$ 27.0
East Bend Station [Member]
Production Capacity (MW)	186
DP&L [Member]
Construction Work in Process	27.0
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] | 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 Investment [Member] | Beckjord Unit 6 [Member]
Gross Plant In Service	2.0
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	23.0
Accumulated Depreciation	1.0
Construction Work in Process	1.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | East Bend Station [Member]
Construction Work in Process	2.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Killen Station [Member]
Gross Plant In Service	309.0
Accumulated Depreciation	9.0
Construction Work in Process	2.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Miami Fort Units 7 and 8 [Member]
Gross Plant In Service	212.0
Accumulated Depreciation	16.0
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	207.0
Accumulated Depreciation	13.0
Construction Work in Process	18.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Zimmer Station [Member]
Gross Plant In Service	178.0
Accumulated Depreciation	27.0
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	973.0
Accumulated Depreciation	71.0
Construction Work in Process	27.0
DP&L Investment [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	42.0
Accumulated Depreciation	4.0
DP&L Investment [Member] | DP&L [Member] | Beckjord Unit 6 [Member]
Gross Plant In Service	75.0
Accumulated Depreciation	70.0
SCR and FGD Equipment Installed and In Service	No
DP&L Investment [Member] | DP&L [Member] | Conesville Unit 4 [Member]
Gross Plant In Service	20.0
Accumulated Depreciation	1.0
Construction Work in Process	1.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | East Bend Station [Member]
Gross Plant In Service	1.0
Accumulated Depreciation	1.0
Construction Work in Process	2.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Killen Station [Member]
Gross Plant In Service	622.0
Accumulated Depreciation	306.0
Construction Work in Process	2.0
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	154.0
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	745.0
Accumulated Depreciation	312.0
Construction Work in Process	18.0
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | DP&L [Member] | Zimmer Station [Member]
Gross Plant In Service	1,099.0
Accumulated Depreciation	661.0
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	3,020.0
Accumulated Depreciation	1,566.0
Construction Work in Process	27.0
DP&L Investment [Member] | DP&L [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	98.0
Accumulated Depreciation	$ 61.0