Consolidated Statements of Comprehensive Income/(Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
NET INCOME / (LOSS)	$ 13.8	$ 35.7	$ (4.7)
Derivative activity:
Reclassification of earnings, net of income tax benefit/(expense)	(0.8)	(0.8)	(0.8)
Total change in fair value of derivatives	(0.8)	(0.8)	(0.8)
Unfunded pension and other postretirement activity:
Prior service cost for the period, net of income tax benefit/(expense)		(0.3)	0.1
Net loss for the period, net of income tax benefit/(expense)		(1.3)	2.1
Reclassification to earnings, net of income tax benefit/(expense)		0.2	1.0
Total change in unfunded pension obligation	0.1	(1.4)	3.2
Other comprehensive income / (loss)	(0.7)	(2.2)	2.4
Net comprehensive income / (loss)	13.1	33.5	(2.3)
Income tax (expense)/benefit on prior service cost related to pension and postretirement activity		0.1	0.0
Income tax (expense)/benefit on net loss related to pension and postretirement activity		0.3	(0.7)
Tax expense (benefit)	3.0	(6.6)	9.6
Other comprehensive loss before reclassifications	0.0	(1.6)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Other comprehensive income / (loss)	0.1	(1.4)
Other comprehensive loss before reclassifications		(1.6)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Other comprehensive income / (loss)	(0.8)	(0.8)
Other comprehensive loss before reclassifications		0.0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Tax expense (benefit)		(0.0)	(0.3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Tax expense (benefit)	0.2	0.2	0.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
NET INCOME / (LOSS)	36.9	61.4	18.9
Unfunded pension and other postretirement activity:
Prior service cost for the period, net of income tax benefit/(expense)		(0.3)	0.1
Net loss for the period, net of income tax benefit/(expense)		(1.2)	2.2
Reclassification to earnings, net of income tax benefit/(expense)		0.4	2.7
Total change in unfunded pension obligation	(1.5)	1.1	(5.0)
Other comprehensive income / (loss)	1.5	(1.1)	5.0
Net comprehensive income / (loss)	38.4	60.3	23.9
Tax expense (benefit)	(3.2)	(13.5)	$ 3.1
THE DAYTON POWER AND LIGHT COMPANY [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Other comprehensive income / (loss)	$ 1.5	(1.1)
Other comprehensive loss before reclassifications		$ (1.5)