Property, Plant and Equipment with Corresponding Depreciation Rates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
Total property, plant and equipment in service	$ 2,193.6	$ 1,990.4
Total property, plant and equipment in service, Composite Rate	3.30%	3.70%	3.80%
Regulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 399.2	$ 306.9
Distribution	1,658.9	1,547.0
General	20.7	34.1
Non-depreciable	79.4	71.2
Total property, plant and equipment in service	$ 2,158.2	$ 1,959.2
Transmission, Composite Rate	2.40%	3.10%
Distribution, Composite Rate	3.70%	4.00%
General, Composite Rate	5.20%	3.20%
Unregulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Non-depreciable	$ 4.8	$ 4.7
Total property, plant and equipment in service	35.4	31.2
Other	$ 30.6	$ 26.5
Other, Composite Rate	3.70%	4.20%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total property, plant and equipment in service	$ 2,752.7	$ 2,571.3
Total property, plant and equipment in service, Composite Rate	2.80%	2.80%	2.80%
THE DAYTON POWER AND LIGHT COMPANY [Member] | Regulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 545.3	$ 456.5
Distribution	2,093.8	1,996.6
General	34.2	48.0
Non-depreciable	$ 79.4	$ 70.2
Transmission, Composite Rate	2.00%	2.10%
Distribution, Composite Rate	3.10%	3.10%
General, Composite Rate	4.00%	2.30%