Equity (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Class of Stock [Line Items]
Equity Contribution from Parent	$ 0.0	$ (200.0)	$ (239.0)
Retained earnings / (deficit)	$ (2,652.1)	(2,673.1)	(2,686.9)	$ (2,722.6)
Non-cash capital contribution		200.0	239.0
Cash Contribution from Parent Company		200.0	260.0
Payment against tax receivable balance from Parent			21.0
CDPQ Investment percent	30.00%
Proceeds from Noncontrolling Interests	$ 537.5
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	$ 0.8
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum Range	1.00
Debt Covenant, Interest Coverage Ratio, Range	1.00
Ohio Holdings
Class of Stock [Line Items]
Subsidiary, Ownership Percentage, Parent	100.00%
Accumulated Other Comprehensive Income/(Loss) [Member]
Class of Stock [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	$ 2.7
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
CDPQ Investment total	$ 544.0
Other Paid-In Capital [Member]
Class of Stock [Line Items]
Equity Contribution from Parent		$ (200.0)	$ (239.0)