Property, Plant and Equipment with Corresponding Depreciation Rates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Total property, plant and equipment in service	$ 2,521.9	$ 2,193.6
Total property, plant and equipment in service, Composite Rate	3.20%	3.30%	3.70%
Regulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 505.3	$ 399.2
Distribution	1,860.9	1,658.9
General	19.3	20.7
Non-depreciable	99.5	79.4
Total property, plant and equipment in service	$ 2,485.0	$ 2,158.2
Transmission, Composite Rate	2.50%	2.40%
Distribution, Composite Rate	3.50%	3.70%
General, Composite Rate	5.90%	5.20%
Unregulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Non-depreciable	$ 5.6	$ 4.8
Total property, plant and equipment in service	36.9	35.4
Other	$ 31.3	$ 30.6
Other, Composite Rate	4.10%	3.70%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total property, plant and equipment in service	$ 3,063.2	$ 2,752.7
Total property, plant and equipment in service, Composite Rate	2.60%	2.80%	2.80%
THE DAYTON POWER AND LIGHT COMPANY [Member] | Regulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 648.0	$ 545.3
Distribution	2,283.4	2,093.8
General	32.2	34.2
Non-depreciable	$ 99.6	$ 79.4
Transmission, Composite Rate	2.00%	2.00%
Distribution, Composite Rate	2.90%	3.10%
General, Composite Rate	3.50%	4.00%