Regulated Matters (Narrative Details) - USD ($) $ in Millions		12 Months Ended
	Nov. 05, 2025	Dec. 31, 2025	Dec. 31, 2024
Regulatory Asset [Line Items]
Revenue Increase - Distribution Rate Case	$ 167.9
Return on Equity - Distribution Rate Case	9.999%
Cost of Long-term Debt - Distribution Rate Case	4.49%
Rate Base - Distribution Rate Case	$ 1,250.0
Capital Structure - Equity - Distribution Rate Case	53.87%
Capital Structure - Long-term Debt - Distribution Rate Case	46.13%
Return on Equity SEET Threshold		9.85%
Regulatory assets earning a return		$ 17.2
Regulatory Liabilities		191.3	$ 179.7
Tax Savings Credit Rider		13.6
Regulatory assets earning a return (non-current)		15.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
RSC Rider		79.0
Regulatory Liabilities		$ 1.6