Condensed Consolidated Balance Sheets - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 36.8		$ 36.8		$ 90.5
Restricted cash	17.6		17.6		21.2
Accounts receivable, net	69.8		69.8		90.5
Inventories	13.0		13.0		10.7
Taxes applicable to subsequent years	18.2		18.2		72.6
Regulatory assets, current	40.2		40.2		41.1
Prepayments and other current assets	9.3		9.3		12.9
Assets Held-for-sale, Not Part of Disposal Group, Current	8.3		8.3		8.7
Total current assets	213.2		213.2		348.2
Property, plant & equipment:
Property, plant & equipment	1,664.2		1,664.2		1,615.6
Less: Accumulated depreciation and amortization	(350.3)		(350.3)		(310.8)
Property, plant and equipment, net of depreciation	1,313.9		1,313.9		1,304.8
Construction work in process	94.5		94.5		32.2
Total net property, plant & equipment	1,408.4		1,408.4		1,337.0
Other non-current assets:
Regulatory assets, non-current	154.7		154.7		152.6
Intangible assets, net of amortization	19.3		19.3		18.4
Other non-current assets	20.5		20.5		21.6
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	0.2		0.2		5.3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(0.4)	$ (0.2)	(0.9)	$ (0.6)
Total other non-current assets	194.7		194.7		197.9
Total assets	1,816.3		1,816.3		1,883.1
Current liabilities:
Current portion of long-term debt	237.6		237.6		103.6
Accounts payable	52.9		52.9		58.1
Accrued taxes	78.5		78.5		76.7
Accrued interest	27.2		27.2		14.3
Security deposits	20.3		20.3		21.3
Regulatory liabilities, current	36.5		36.5		34.9
Other current liabilities	21.4		21.4		22.0
Liabilities Held for Sale, Current	9.9		9.9		12.2
Total current liabilities	484.3		484.3		343.1
Non-current liabilities:
Long-term debt	1,223.3		1,223.3		1,372.3
Deferred taxes	119.0		119.0		116.1
Taxes payable	3.7		3.7		76.1
Regulatory liabilities, non-current	252.3		252.3		278.3
Pension, retiree and other benefits	73.9		73.9		82.3
Asset Retirement Obligations, Noncurrent	9.5		9.5		9.4
Other deferred credits	7.5		7.5		8.0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	52.4		52.4		69.2
Total non-current liabilities	1,741.6		1,741.6		2,011.7
Commitments and contingencies
Common shareholder's equity:
Common stock	0.0		0.0		0.0
Other paid-in capital	2,373.4		2,373.4		2,370.5
Accumulated other comprehensive income	0.0		0.0		2.2
Retained earnings/ (deficit)	(2,783.0)		(2,783.0)		(2,844.4)
Total common shareholder's equity	(409.6)	(509.5)	(409.6)	(509.5)	(471.7)
Total liabilities and shareholder's equity	1,816.3		1,816.3		1,883.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Current assets:
Cash and cash equivalents	14.4		14.4		45.0
Restricted cash	17.6		17.6		21.2
Accounts receivable, net	71.7		71.7		90.4
Inventories	9.8		9.8		7.7
Taxes applicable to subsequent years	18.1		18.1		72.4
Regulatory assets, current	40.2		40.2		41.1
Income Taxes Receivable, Current	17.4		17.4		19.6
Prepayments and other current assets	8.6		8.6		13.3
Total current assets	197.8		197.8		310.7
Property, plant & equipment:
Property, plant & equipment	2,306.5		2,306.5		2,274.4
Less: Accumulated depreciation and amortization	(1,010.4)		(1,010.4)		(988.0)
Property, plant and equipment, net of depreciation	1,296.1		1,296.1		1,286.4
Construction work in process	93.0		93.0		31.7
Total net property, plant & equipment	1,389.1		1,389.1		1,318.1
Other non-current assets:
Regulatory assets, non-current	154.7		154.7		152.6
Intangible assets, net of amortization	18.1		18.1		17.2
Other non-current assets	19.7		19.7		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	192.5		192.5		190.8
Total assets	1,779.4		1,779.4		1,819.6
Current liabilities:
Current portion of long-term debt	199.6		199.6		4.6
Accounts payable	51.1		51.1		55.8
Accrued taxes	78.5		78.5		75.7
Accrued interest	6.5		6.5		0.4
Security deposits	20.3		20.3		21.3
Regulatory liabilities, current	36.5		36.5		34.9
Other current liabilities	16.8		16.8		17.5
Total current liabilities	409.3		409.3		210.2
Non-current liabilities:
Long-term debt	434.6		434.6		581.5
Deferred taxes	132.5		132.5		131.7
Taxes payable	4.9		4.9		77.1
Regulatory liabilities, non-current	252.3		252.3		278.3
Pension, retiree and other benefits	73.9		73.9		83.2
Asset Retirement Obligation	4.7		4.7		4.7
Other deferred credits	7.4		7.4		7.6
Total non-current liabilities	910.3		910.3		1,164.1
Commitments and contingencies
Common shareholder's equity:
Common stock	0.4		0.4		0.4
Other paid-in capital	621.9		621.9		711.8
Accumulated other comprehensive income	(34.2)		(34.2)		(35.3)
Retained earnings/ (deficit)	(128.3)		(128.3)		(231.6)
Total common shareholder's equity	459.8	$ 431.0	459.8	$ 431.0	445.3
Total liabilities and shareholder's equity	$ 1,779.4		$ 1,779.4		$ 1,819.6