Income Taxes (Tax or Benefit credited to AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Tax expense/ (benefit)	$ (0.6)	$ 0.8	$ 2.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income Taxes [Line Items]
Tax expense/ (benefit)	$ (0.3)	$ 1.5	$ 2.9