Cover Document $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) shares
Entity Information [Line Items]
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Voluntary Filers	Yes
Entity Well-known Seasoned Issuer	No
Entity Registrant Name	DPL Inc.
Entity Incorporation, State or Country Code	OH
Entity File Number	1-9052
Entity Address, Address Line One	1065 Woodman Drive
Entity Address, City or Town	Dayton
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45432
City Area Code	937
Local Phone Number	259-7215
Entity Tax Identification Number	31-1163136
Document Fiscal Period Focus	FY
Entity Public Float | $	$ 0.0
Entity Central Index Key	0000787250
Amendment Flag	false
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding	1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Entity Voluntary Filers	Yes
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Registrant Name	THE DAYTON POWER AND LIGHT COMPANY
Entity Incorporation, State or Country Code	OH
Entity File Number	1-2385
Entity Address, Address Line One	1065 Woodman Drive
Entity Address, City or Town	Dayton
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45432
City Area Code	937
Local Phone Number	259-7215
Entity Tax Identification Number	31-0258470
Document Fiscal Period Focus	FY
Entity Central Index Key	0000027430
Amendment Flag	false
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding	41,172,173