Equity (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Equity Contribution from Parent	$ (200.0)	$ (239.0)	$ 0.0
Retained earnings / (deficit)	$ (2,673.1)	$ (2,686.9)
Common stock, shares authorized	1,500	1,500
Common stock, shares outstanding	1	1
Non-cash capital contribution		$ 239.0
Cash Contribution from Parent Company	$ 200.0	260.0
Payment against tax receivable balance from Parent		21.0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Equity Contribution from Parent	(200.0)	(260.0)	0.0
Retained earnings / (deficit)	$ 26.2	$ 29.3
Common stock, shares authorized	50,000,000
Common stock, shares outstanding	41,172,173	41,172,173
Dividends, Common Stock, Cash	$ 40.0	$ (83.0)	64.0
Payments of Ordinary Dividends, Common Stock	40.0		64.0
Other Paid-In Capital [Member]
Class of Stock [Line Items]
Equity Contribution from Parent	(200.0)	(239.0)
Other Paid-In Capital [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Equity Contribution from Parent	200.0	260.0	0.0
Dividends, Common Stock, Cash	0.0	56.3	49.0
Payments of Ordinary Dividends, Common Stock	$ 40.0	83.0
Dividends, Common Stock		$ 83.0	$ 64.0