Consolidated Statements of Comprehensive Income/(Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net income / (loss)	$ (4.7)	$ 22.1	$ (1.0)
Derivative activity:
Reclassification of earnings, net of income tax benefit/(expense)	(0.8)	(0.8)	(0.9)
Unfunded pension and other postretirement activity:
Prior service cost for the period, net of income tax benefit/(expense)	0.1	0.0	0.0
Net loss for the period, net of income tax benefit/(expense)	2.1	6.4	(8.8)
Reclassification to earnings, net of income tax benefit/(expense)	1.0	1.9	1.0
Total change in unfunded pension obligation	3.2	8.3	(7.8)
Other comprehensive income / (loss)	2.4	7.5	(8.7)
Net comprehensive income / (loss)	(2.3)	29.6	(9.7)
Income tax (expense)/benefit on prior service cost related to pension and postretirement activity	0.0	0.0	0.0
Income tax (expense)/benefit on net loss related to pension and postretirement activity	(0.7)	(1.8)	2.6
Tax expense (benefit)	9.6	0.5	5.5
Other comprehensive income before reclassifications	2.2	6.4
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Unfunded pension and other postretirement activity:
Other comprehensive income / (loss)	3.2	8.3
Other comprehensive income before reclassifications	2.2	6.4
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 income before reclassifications	0.0	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)	(0.3)	(0.6)	(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)	18.9	47.1	51.1
Derivative activity:
Change in derivative fair value, net of income tax benefit/(expense)	0.0	0.0	(0.2)
Reclassification of earnings, net of income tax benefit/(expense)	0.0	0.0	(0.6)
Total change in fair value of derivatives	0.0	0.0	0.4
Unfunded pension and other postretirement activity:
Prior service cost for the period, net of income tax benefit/(expense)	0.1	0.0	0.0
Net loss for the period, net of income tax benefit/(expense)	2.2	6.4	(8.7)
Reclassification to earnings, net of income tax benefit/(expense)	2.7	3.9	3.1
Total change in unfunded pension obligation	(5.0)	(10.3)	5.6
Other comprehensive income / (loss)	5.0	10.3	(5.2)
Net comprehensive income / (loss)	23.9	57.4	45.9
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	0.0	0.0	(0.2)
Income tax (expense)/benefit on prior service cost related to pension and postretirement activity	0.0	0.0	0.0
Income tax (expense)/benefit on net loss related to pension and postretirement activity	(0.6)	(1.8)	2.6
Tax expense (benefit)	3.1	(5.7)	(7.0)
Other comprehensive income before reclassifications	2.3	6.4
THE DAYTON POWER AND LIGHT COMPANY [Member] | 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)	(0.9)	(1.1)	(0.9)
THE DAYTON POWER AND LIGHT COMPANY [Member] | 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)	$ 0.0	$ 0.0	$ 0.8