Equity (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)
Class of Stock [Line Items]
Retained earnings / (deficit)	$ (2,722.6)	$ (2,717.9)
Common stock, shares authorized | shares	1,500	1,500
Common stock, shares outstanding | shares	1	1
Non-cash capital contribution		$ 132.5	$ 98.0
Cash Contribution from Parent Company		150.0	150.0
Payment against tax receivable balance from Parent		17.5	52.0
Debt Covenant, Leverage Ratio, Maximum	0.67
Equity Contribution from Parent	$ 0.0	(132.5)	(98.0)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Retained earnings / (deficit)	$ (5.4)	$ (8.9)
Common stock, shares authorized | shares	50,000,000	50,000,000
Common stock, shares outstanding | shares	41,172,173	41,172,173
Dividends, Common Stock, Cash	$ 64.0	$ (42.0)	52.7
Payments of Ordinary Dividends, Common Stock	64.0		42.7
Equity Contribution from Parent	0.0	(150.0)	(150.0)
Other Paid-In Capital [Member]
Class of Stock [Line Items]
Equity Contribution from Parent		(132.5)	(98.0)
Other Paid-In Capital [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Dividends, Common Stock, Cash	49.0	42.0	52.7
Payments of Ordinary Dividends, Common Stock	$ 64.0	52.0	42.7
Dividends, Common Stock		42.0
Equity Contribution from Parent		$ 150.0	$ 150.0