Condensed Consolidated Balance Sheets - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 31.1		$ 31.1		$ 90.5
Restricted cash	11.5		11.5		21.2
Accounts receivable, net	67.5		67.5		90.5
Inventories	14.7		14.7		10.7
Taxes applicable to subsequent years	36.3		36.3		72.6
Regulatory assets, current	43.5		43.5		41.1
Other prepayments and current assets	14.7		14.7		12.9
Assets Held-for-sale, Not Part of Disposal Group, Current	4.2		4.2		8.7
Total current assets	223.5		223.5		348.2
Property, plant & equipment:
Property, plant & equipment	1,651.4		1,651.4		1,615.6
Less: Accumulated depreciation and amortization	(337.4)		(337.4)		(310.8)
Property, plant and equipment, net of depreciation	1,314.0		1,314.0		1,304.8
Construction work in process	75.5		75.5		32.2
Total net property, plant & equipment	1,389.5		1,389.5		1,337.0
Other non-current assets:
Regulatory assets, non-current	158.0		158.0		152.6
Intangible assets, net of amortization	20.4		20.4		18.4
Other deferred assets	21.1		21.1		21.6
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	5.2		5.2		5.3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(0.3)	$ 0.0	(0.5)	$ (0.4)
Total other non-current assets	204.7		204.7		197.9
Total assets	1,817.7		1,817.7		1,883.1
Current liabilities:
Current portion of long-term debt	63.2		63.2		103.6
Accounts payable	84.5		84.5		58.1
Accrued taxes	74.2		74.2		76.7
Accrued interest	11.9		11.9		14.3
Security deposits	22.0		22.0		21.3
Regulatory liabilities, current	36.1		36.1		34.9
Other current liabilities	18.1		18.1		22.0
Liabilities Held for Sale, Current	10.6		10.6		12.2
Total current liabilities	320.6		320.6		343.1
Non-current liabilities:
Long-term debt	1,363.9		1,363.9		1,372.3
Deferred taxes	114.6		114.6		116.1
Taxes payable	40.0		40.0		76.1
Regulatory liabilities, non-current	281.7		281.7		278.3
Pension, retiree and other benefits	74.5		74.5		82.3
Asset Retirement Obligations, Noncurrent	9.5		9.5		9.4
Other deferred credits	7.0		7.0		8.0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	52.7		52.7		69.2
Total non-current liabilities	1,943.9		1,943.9		2,011.7
Commitments and contingencies
Common shareholder's equity:
Common stock	0.0		0.0		0.0
Other paid-in capital	2,370.6		2,370.6		2,370.5
Accumulated other comprehensive income	1.0		1.0		2.2
Retained earnings/ (deficit)	(2,818.4)		(2,818.4)		(2,844.4)
Total common shareholder's equity	(446.8)	(534.1)	(446.8)	(534.1)	(471.7)
Total liabilities and shareholder's equity	1,817.7		1,817.7		1,883.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Current assets:
Cash and cash equivalents	5.6		5.6		45.0
Restricted cash	11.5		11.5		21.2
Accounts receivable, net	71.6		71.6		90.4
Inventories	11.2		11.2		7.7
Taxes applicable to subsequent years	36.2		36.2		72.4
Regulatory assets, current	43.5		43.5		41.1
Income Taxes Receivable, Current	16.8		16.8		19.6
Other prepayments and current assets	11.0		11.0		13.3
Total current assets	207.4		207.4		310.7
Property, plant & equipment:
Property, plant & equipment	2,305.7		2,305.7		2,274.4
Less: Accumulated depreciation and amortization	(1,009.8)		(1,009.8)		(988.0)
Property, plant and equipment, net of depreciation	1,295.9		1,295.9		1,286.4
Construction work in process	74.2		74.2		31.7
Total net property, plant & equipment	1,370.1		1,370.1		1,318.1
Other non-current assets:
Regulatory assets, non-current	158.0		158.0		152.6
Intangible assets, net of amortization	19.3		19.3		17.2
Other deferred assets	20.3		20.3		21.0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0.0	(0.2)	(0.1)	(0.5)
Total other non-current assets	197.6		197.6		190.8
Total assets	1,775.1		1,775.1		1,819.6
Current liabilities:
Current portion of long-term debt	0.2		0.2		4.6
Accounts payable	82.2		82.2		55.8
Accrued taxes	76.0		76.0		75.7
Accrued interest	2.0		2.0		0.4
Security deposits	22.0		22.0		21.3
Regulatory liabilities, current	36.1		36.1		34.9
Other current liabilities	13.2		13.2		17.5
Total current liabilities	231.7		231.7		210.2
Non-current liabilities:
Long-term debt	575.2		575.2		581.5
Deferred taxes	125.5		125.5		131.7
Taxes payable	41.1		41.1		77.1
Regulatory liabilities, non-current	281.7		281.7		278.3
Pension, retiree and other benefits	74.5		74.5		83.2
Asset Retirement Obligation	4.7		4.7		4.7
Other deferred credits	7.4		7.4		7.6
Total non-current liabilities	1,110.1		1,110.1		1,164.1
Commitments and contingencies
Common shareholder's equity:
Common stock	0.4		0.4		0.4
Other paid-in capital	641.8		641.8		711.8
Accumulated other comprehensive income	(35.8)		(35.8)		(35.3)
Retained earnings/ (deficit)	(173.1)		(173.1)		(231.6)
Total common shareholder's equity	433.3	$ 419.1	433.3	$ 419.1	445.3
Total liabilities and shareholder's equity	$ 1,775.1		$ 1,775.1		$ 1,819.6