Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Entity Information [Line Items]
Unrealized Gain (Loss) on Investments	$ 0.7	$ 0.5
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Unrealized Gain (Loss) on Investments	$ 0.7	$ 0.5

Amount of unrealized gain (loss) on investment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration