Income Taxes (Effective and Statutory Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Entity Information [Line Items]
Non-cash capital contribution		$ 239.0
Statutory Federal tax rate	21.00%	21.00%	21.00%
State taxes, net of Federal tax benefit	5.20%	2.50%	(1.60%)
Depreciation of flow-through differences	(4.50%)	(0.20%)	2.50%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation and Amortization, Percent	(50.40%)	(7.60%)	43.80%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(0.10%)	0.00%	0.10%
Other, net	1.00%	(0.10%)	1.30%
Effective tax rate	(27.80%)	15.60%	67.10%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Statutory Federal tax rate	21.00%	21.00%	21.00%
State taxes, net of Federal tax benefit	1.40%	1.40%	1.40%
Depreciation of flow-through differences	(1.20%)	(0.10%)	(2.20%)
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Percent	0.00%	0.00%	(0.10%)
Effective Income Tax Rate Reconciliation, Depreciation of flow-through years	(13.50%)	(4.30%)	(39.40%)
Other, net	0.30%	0.00%	(0.30%)
Effective tax rate	8.00%	18.00%	(19.60%)