Property, Plant and Equipment (Changes in the Liability for Transmission and Distribution Asset Removal Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Changes in Liability for Transmission and Distribution Asset Removal Costs [Roll Forward]
Balance at January 1	$ 145.2	$ 138.8
Additions	17.6	17.0
Settlements	(26.0)	(10.6)
Balance at December 31	136.8	145.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Changes in Liability for Transmission and Distribution Asset Removal Costs [Roll Forward]
Balance at January 1	145.2	138.8
Additions	17.6	17.0
Settlements	(26.0)	(10.6)
Balance at December 31	$ 136.8	$ 145.2