Income Taxes (Effective and Statutory Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Entity Information [Line Items]
Non-cash capital contribution		$ 132.5	$ 98.0
Statutory Federal tax rate	21.00%	21.00%	21.00%
State taxes, net of Federal tax benefit	(1.60%)	2.80%	(13.10%)
Depreciation of flow-through differences	2.50%	3.30%	(23.60%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation and Amortization, Percent	43.80%	(29.00%)	94.80%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	0.10%	(0.60%)	4.10%
Other, net	1.30%	(0.80%)	1.20%
Effective tax rate	67.10%	(3.30%)	84.40%
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%	1.10%	1.50%
Depreciation of flow-through differences	(2.20%)	1.30%	2.60%
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Percent	(0.10%)	(0.20%)	(0.50%)
Effective Income Tax Rate Reconciliation, Depreciation of flow-through years	(39.40%)	(11.70%)	(10.60%)
Effective Income Tax Rate Reconciliation, Change in Tax Reserves, Percent	0.00%	(0.10%)	(6.10%)
Other, net	(0.30%)	(0.60%)	4.10%
Effective tax rate	(19.60%)	10.80%	12.00%