Regulated Matters (Regulatory Assets and Liabilities Table Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Regulatory Asset [Line Items]
Regulatory Assets, Current	$ 61.1	$ 82.0
Regulatory Assets, Noncurrent	137.4	140.0
Regulatory Assets	198.5	222.0
Regulatory Liability, Noncurrent	189.5	169.4
Regulatory Liability, Current	$ 1.8	10.3
Regulatory Noncurrent Liability, End Date for Recovery	2027
Regulatory Liabilities	$ 191.3	179.7
THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Asset [Line Items]
Regulatory Liabilities	$ 1.6
Overcollection of costs to be refunded [Member]
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 0.2	9.3
Transmission Formula Rate Credits
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Liabilities Type of Recovery	A
Regulatory Liability, Noncurrent	$ 1.6	1.0
Removal Costs [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	139.9	131.0
Deferred Income Tax Charge [Member]
Regulatory Asset [Line Items]
Regulatory Liability, Noncurrent	$ 44.4	35.0
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	$ 0.0	1.5
Overcollection of costs to be refunded (Non-Current)
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B
Regulatory Liability, Noncurrent	$ 2.3	0.0
Other non-current regulatory liabilities
Regulatory Asset [Line Items]
Regulatory Liabilities Type of Recovery	B/C
Regulatory Liability, Noncurrent	$ 2.9	1.9
Regulatory Noncurrent Liability, Ongoing	Ongoing
Undercollections to be collected [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Assets, Current	$ 52.2	63.4
Amounts being recovered through base rates [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2026
Regulatory Assets, Current	$ 7.2	4.8
Transmission Formula Rate Debits
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Assets, Current	$ 1.7	13.8
Regulatory Assets, Noncurrent	$ 10.2	1.2
Transmission Formula Rate Debits - Current
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2026
Pension Costs [Member]
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A
Regulatory Current Asset, End Date for Recovery	Ongoing
Regulatory Assets, Noncurrent	$ 49.8	58.8
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	$ 0.0	0.5
Transmission Formula Rate Debits - Non-current
Regulatory Asset [Line Items]
Regulatory Current Asset, End Date for Recovery	2027
Undercollections to be collected (Non-Current)
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	A/B/C
Regulatory Current Asset, End Date for Recovery	Various
Regulatory Assets, Noncurrent	$ 60.4	65.9
Amount being recovered through base rates (Non-Current)
Regulatory Asset [Line Items]
Regulatory Assets Type of Recovery	B
Regulatory Current Asset, End Date for Recovery	2030
Regulatory Assets, Noncurrent	$ 17.0	$ 13.6

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- Definition

Regulatory Liabilities Type of Recovery

+ References

No definition available.

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- Definition

Regulatory Liability, Amortization Through

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- Definition

Regulatory Noncurrent Liability, End Date for Recovery

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Regulatory Noncurrent Liability, Ongoing

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478742/980-340-50-1

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

+ References

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- Definition

The end date for recovery of the individual regulatory current asset in a schedule of regulatory current assets.

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- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 405
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477571/980-405-25-1

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- Definition

The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

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- Definition

The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(24))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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