Document and Entity Information	12 Months Ended
	Dec. 31, 2018 USD ($) shares
Entity Registrant Name	DPL INC
Entity Central Index Key	0000787250
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding | shares	1
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Voluntary Filers	Yes
Entity Well-known Seasoned Issuer	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float | $	$ 0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Registrant Name	THE DAYTON POWER & LIGHT CO
Entity Central Index Key	0000027430
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding | shares	41,172,173
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Voluntary Filers	Yes
Entity Well-known Seasoned Issuer	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float | $	$ 0