Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 32.0	$ 35.9
Deferred tax assets related to state and local tax net operating loss carryforwards, net of related valuation allowances	31.8	35.7
Unrecognized Tax Benefits	0.4	0.4	$ 0.4	$ 0.4
Decrease in Unrecognized Tax Benefits Due To Uncertainty In Timing of Deductibility	0.0	0.0	0.0
Unrecognized tax benefits anticipated to result in a decrease of unrecognized tax benefits with 12 months of the balance sheet date, minimum	0.0
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]
Income Taxes [Line Items]
Unrecognized Tax Benefits	0.4	0.4	0.4	$ 0.4
Decrease in Unrecognized Tax Benefits Due To Uncertainty In Timing of Deductibility	$ 0.0	$ 0.0	$ 0.0