Regulated Matters (Regulatory Assets and Liabilities Table Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Regulatory Asset [Line Items]
Regulatory Assets, Current	$ 82.0	$ 56.6
Regulatory Assets, Noncurrent	140.0	155.7
Regulatory Assets	222.0	212.3
Regulatory Liability, Noncurrent	169.4	182.1
Regulatory Liability, Current	10.3	18.0
Regulatory Liabilities	179.7	200.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets, Current	82.0	56.6
Regulatory Assets, Noncurrent	140.0	155.7
Regulatory Assets	222.0	212.3
Regulatory Liability, Noncurrent	169.4	182.1
Regulatory Liability, Current	10.3	18.0
Regulatory Liabilities	$ 179.7	200.1
Overcollection of costs to be refunded [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	A/B
Regulatory Liability, Noncurrent	$ 9.3	14.7
Overcollection of costs to be refunded [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	A/B
Regulatory Liability, Noncurrent	$ 9.3	14.7
Transmission Formula Rate Credits
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 1.0	3.3
Transmission Formula Rate Credits | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 1.0	3.3
Removal Costs [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	131.0	134.2
Removal Costs [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	131.0	134.2
Deferred Income Tax Charge [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	$ 35.0	42.6
Regulatory Liability, Amortization Through	Ongoing
Deferred Income Tax Charge [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	$ 35.0	42.6
Regulatory Liability, Amortization Through	Ongoing
TCJA Regulatory Liability [Member] [Domain]
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 0.0	1.0
Regulatory Liability, Amortization Through	Ongoing
TCJA Regulatory Liability [Member] [Domain] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 0.0	1.0
Regulatory Liability, Amortization Through	Ongoing
Transmission Formula Rate Credits, Noncurrent
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 1.5	0.0
Transmission Formula Rate Credits, Noncurrent | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 1.5	0.0
PJM transmission enhancement settlement repayment amount [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 0.0	1.7
PJM transmission enhancement settlement repayment amount [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 0.0	1.7
Postretirement Benefit Costs [Member]
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 1.9	2.6
Regulatory Liability, Amortization Through	Ongoing
Postretirement Benefit Costs [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 1.9	2.6
Regulatory Liability, Amortization Through	Ongoing
Undercollections to be collected [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B/D
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 63.4	51.7
Undercollections to be collected [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B/D
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 63.4	51.7
Amounts being recovered through base rates [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 1.7	1.7
Amounts being recovered through base rates [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 1.7	1.7
Vegetation management costs recovered in base rates
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 2.7	2.7
Vegetation management costs recovered in base rates | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 2.7	2.7
Rate case expenses recovered through base rates
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 0.4	0.5
Rate case expenses recovered through base rates | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Current	$ 0.4	0.5
Transmission Formula Rate Debits
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Assets, Current	$ 13.8	0.0
Regulatory Assets, Noncurrent	$ 1.2	6.7
Transmission Formula Rate Debits | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Assets, Current	$ 13.8	0.0
Regulatory Assets, Noncurrent	$ 1.2	6.7
Transmission Formula Rate Debits - Current
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Transmission Formula Rate Debits - Current | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2025
Pension Costs [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Current Asset, End Date for Recovery	Ongoing
Regulatory Assets, Noncurrent	$ 58.8	62.6
Pension Costs [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Current Asset, End Date for Recovery	Ongoing
Regulatory Assets, Noncurrent	$ 58.8	62.6
Energy Efficiency
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent	$ 4.1	4.1
Energy Efficiency | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent	$ 4.1	4.1
Deferred Regulatory Compliance Costs [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 33.2	45.0
Deferred Regulatory Compliance Costs [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 33.2	45.0
Ccem Smart Grid And Advanced Metering Infrastructure Cost [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	C
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 1.8	3.2
Ccem Smart Grid And Advanced Metering Infrastructure Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	C
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 1.8	3.2
Loss on Reacquired Debt [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	Ongoing
Regulatory Assets, Noncurrent	$ 0.5	1.1
Loss on Reacquired Debt [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	Ongoing
Regulatory Assets, Noncurrent	$ 0.5	1.1
Storm Costs [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Noncurrent	$ 0.0	2.2
Storm Costs [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2025
Regulatory Assets, Noncurrent	$ 0.0	2.2
Storm Costs
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 2.4	1.5
Storm Costs | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 2.4	1.5
Vegetation Management [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent		19.9
Vegetation Management [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent		19.9
Vegetation Management and Other [Member]
Regulatory Asset [Line Items]
Regulatory Assets, Noncurrent	$ 21.7
Vegetation Management and Other [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets, Noncurrent	$ 21.7
CIS Replacement Costs
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 8.8	3.1
CIS Replacement Costs | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 8.8	3.1
Transmission Formula Rate Debits - Non-current
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Transmission Formula Rate Debits - Non-current | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Customer Program Rider
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 2.9	0.0
Customer Program Rider | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/D
Regulatory Current Asset, End Date for Recovery	Undetermined
Regulatory Assets, Noncurrent	$ 2.9	0.0
Uncollectible and Other [Member] [Domain]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent	$ 4.6	6.3
Uncollectible and Other [Member] [Domain] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2028
Regulatory Assets, Noncurrent	$ 4.6	$ 6.3