Dayton Power & Light 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2019shares
Entity Registrant Name	DPL INC
Entity Central Index Key	0000787250
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
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	1
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Registrant Name	DAYTON POWER & LIGHT CO
Entity Central Index Key	0000027430
Document Type	10-Q
Amendment Flag	false
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	41,172,173
Entity Emerging Growth Company	false
Entity Small Business	false

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues	$ 199	$ 207.7	$ 592.2	$ 591.5
Operating costs and expenses
Net fuel cost	5.2	4.6	13	12.7
Utilities Operating Expense, Purchased Power	66.5	83.6	195	238.9
Operating expenses:
Operation and maintenance	44.2	37.3	142.3	118.3
Depreciation and amortization	17.7	19.7	54.1	58.8
Taxes other than income taxes	20.9	19	58.5	54.5
Other Operating Income (Expense), Net	0	1.6	0.9	14.6
Other, net (Note 2)			0.9	(0.6)
Costs and Expenses	154.5	165.8	463.8	497.8
Operating income	44.5	41.9	128.4	93.7
Other income / (expense), net:
Interest expense	(18.3)	(22.6)	(63.7)	(74.4)
Loss on early extinguishment of debt	0	0	(44.9)	(6.4)
Other income	0.3	0.5	3.2	0.8
Total other expense, net	(18)	(22.1)	(105.4)	(80)
Income from continuing operations before income tax	26.5	19.8	23	13.7
Income tax expense / (benefit) from continuing operations	(9.4)	3.1	(12.6)	1.5
Net income from continuing operations	35.9	16.7	35.6	12.2
Income / (loss) from discontinued operations before income tax	(0.4)	5	32.8	36.7
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0	0.3	0.1	(1.6)
Income tax expense from discontinued operations	0.1	1	7.1	5.9
Net income / (loss) from discontinued operations	(0.5)	4.3	25.8	29.2
Net income	35.4	21	61.4	41.4
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	191.1	198.7	570.2	563.5
Operating costs and expenses
Net fuel cost	0.6	0.1	2	1.7
Utilities Operating Expense, Purchased Power	65.9	83	193.3	235.7
Operating expenses:
Operation and maintenance	42.2	33.8	135.2	105.9
Depreciation and amortization	17.4	19.1	52.9	56.5
Taxes other than income taxes	20.8	19	58.2	54.3
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(0.1)	0	0	0.1
Gain (Loss) on Disposition of Business	0	0	0	12.4
Costs and Expenses	146.8	155	441.6	466.6
Operating income	44.3	43.7	128.6	96.9
Other income / (expense), net:
Interest expense	(6.1)	(5.8)	(19.9)	(20.5)
Loss on early extinguishment of debt	0	0	0	(0.6)
Other income	(0.5)	(0.4)	0.1	(1.9)
Total other expense, net	(6.6)	(6.2)	(19.8)	(23)
Income from continuing operations before income tax	37.7	37.5	108.8	73.9
Income tax expense / (benefit) from continuing operations	(7.2)	6.3	5.1	12
Net income	$ 44.9	$ 31.2	$ 103.7	$ 61.9

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 35.4	$ 21	$ 61.4	$ 41.4
Derivative activity:
Change in derivative fair value, net of income tax	(0.2)	0.1	(1)	0.4
Reclassification of earnings, net of income tax	(0.4)	(0.2)	(0.9)	(0.6)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives Related to Discontinued Operations, Net of Tax	(0.4)	0	(0.4)	2.8
Total change in fair value of derivatives	(1)	(0.1)	(2.3)	2.6
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0	0.1	0.1	0.4
Total change in unfunded pension obligation	0	0.1	0.1	0.4
Other comprehensive income / (loss)	(1)	0	(2.2)	3
Net comprehensive income	34.4	21	59.2	44.4
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income	44.9	31.2	103.7	61.9
Derivative activity:
Change in derivative fair value, net of income tax	(0.1)	0	(0.9)	0.5
Reclassification of earnings, net of income tax	0	(0.2)	(0.1)	(0.5)
Total change in fair value of derivatives	(0.1)	(0.2)	(1)	0
Pension and postretirement activity:
Reclassification to earnings, net of income tax	1.7	0.8	2.1	2.5
Total change in unfunded pension obligation	1.7	0.8	2.1	2.5
Other comprehensive income / (loss)	1.6	0.6	1.1	2.5
Net comprehensive income	$ 46.5	$ 31.8	$ 104.8	$ 64.4

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	$ 0	$ 0	$ 0	$ 0
Income tax (expense) benefit on reclassification to earnings	0	0	0	0
AOCI reclassed to Retained Earnings, income tax	0	0	0	0
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	(0.1)	0	0.1	(0.2)
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	(0.1)	0.1	0	0.3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives Related to Discontinued Operations, Tax	(0.4)	0	(0.4)	(1.5)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	0	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax	0	0	0	0
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	(0.1)	(0.1)	(0.1)	(0.1)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	0	0	0	0
Income tax (expense) benefit on reclassification to earnings	0	0	0	0
AOCI reclassed to Retained Earnings, income tax	0	0	0	0
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	0	(0.1)	0.2	(0.1)
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	0	0.1	0	0.6
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives Related to Discontinued Operations, Tax	0	0	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	0	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax	0	0	0	0
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	$ 0.9	$ (0.2)	$ (0.5)	$ (0.7)

Condensed Consolidated Balance

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		13		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
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
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		119		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
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
Other paid-in capital	2,373.4		2,373.4		2,370.5
Accumulated other comprehensive income	0		0		2.2
Retained earnings/ (deficit)	(2,783)		(2,783)		(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
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)
Property, plant and equipment, net of depreciation	1,296.1		1,296.1		1,286.4
Construction work in process	93		93		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
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	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	459.8	$ 431	445.3
Total liabilities and shareholder's equity	$ 1,779.4		$ 1,779.4		$ 1,819.6

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Common Stock, Shares Authorized	1,500	1,500
Common stock, shares issued	1	1
Common stock, shares outstanding	1	1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Common Stock, Shares Authorized	50,000,000	50,000,000
Common stock, shares outstanding	41,172,173	41,172,173
Common stock, par value (in USD per share)	$ 0.01	$ 0.01

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 61.4	$ 41.4
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	34.2	62.4
Amortization of Debt Issuance Costs	4.3	4.4
Gain (Loss) on Extinguishment of Debt	(44.9)	(6.4)
Deferred income taxes	(8.7)	(17.8)
Impairment of Long-Lived Assets Held-for-use	0	2.8
Gain (Loss) on Disposition of Business, Including Discontinued Operation	(0.1)	13.2
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0.9	(0.6)
Changes in certain assets and liabilities:
Accounts receivable, net	18	34.4
Inventories	(3.2)	14.7
Taxes applicable to subsequent years	56.2	57.7
Deferred regulatory costs, net	2.9	(4.1)
Accounts payable	(5.1)	(17.4)
Accrued taxes	(71)	(47.1)
Accrued interest	12.9	13.4
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(9.3)	(4)
Other	(2)	(6.9)
Net Cash Provided by (Used in) Operating Activities	136.3	152.9
Cash flows from investing activities:
Capital expenditures	(122.4)	(75.8)
Proceeds from disposal and sale of business	0	234.9
Payments for Removal Costs	0	(14.5)
Proceeds from Sale of Property, Plant, and Equipment	0	10.6
Proceeds from Insurance Settlement, Investing Activities	0	2.8
Payments to Acquire Intangible Assets	3.6	0
Other investing activities, net	0.1	(0.5)
Net cash provided by / (used in) investing activities	(125.9)	157.5
Cash flows from financing activities:
Payments of Deferred Finance Costs	(9.2)	0
Repayments of Lines of Credit	(35)	(40)
Proceeds from Issuance of Long-term Debt	821.7	0
Proceeds from Lines of Credit	133	30
Retirement of long-term debt, including early payment premium	(978)	(239.4)
Proceeds from (Payments for) Other Financing Activities	(0.2)	0
Net cash used in financing activities	(67.7)	(249.4)
Cash, cash equivalents, and restricted cash:
Net Cash Provided by (Used in) Discontinued Operations	0	1.5
Restricted Cash and Cash Equivalents	54.4	87.4
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(57.3)	62.5
Supplemental cash flow information:
Interest paid, net of amounts capitalized	47.1	55.2
Proceeds from Income Tax Refunds	1.3	(2)
Non-cash financing and investing activities:
Accruals for capital expenditures	2.3	7.6
Non-cash Proceeds from Sale of Business	0	4.1
Non-cash capital contribution	2.7	30.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income	103.7	61.9
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	52.9	56.5
Gain (Loss) on Extinguishment of Debt	0	(0.6)
Deferred income taxes	(17.2)	(7.5)
Gain (Loss) on Disposition of Business	0	12.4
Changes in certain assets and liabilities:
Accounts receivable, net	18.9	(3.3)
Inventories	(2.1)	(0.2)
Taxes applicable to subsequent years	54.3	54
Deferred regulatory costs, net	2.9	(4.1)
Accounts payable	(4.8)	(1.1)
Accrued taxes	(65.6)	(58.7)
Accrued interest	6	(0.3)
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(9.3)	(3.1)
Other	(0.8)	6.1
Net Cash Provided by (Used in) Operating Activities	138.9	113.2
Cash flows from investing activities:
Capital expenditures	(121.1)	(65)
Payments for Removal Costs	0	(14.5)
Proceeds from Sale of Property, Plant, and Equipment	0	10.6
Proceeds from Insurance Settlement, Investing Activities	0	0.1
Other investing activities, net	(3.5)	(0.2)
Net cash provided by / (used in) investing activities	(124.6)	(69)
Cash flows from financing activities:
Payments of Deferred Finance Costs	(4.6)	0
Repayments of Lines of Credit	0	(40)
Proceeds from Issuance of Long-term Debt	422.3	0
Proceeds from Lines of Credit	60	30
Retirement of long-term debt, including early payment premium	(436.1)	(63.3)
Payments of Ordinary Dividends, Common Stock	(90)	(43.8)
Proceeds from Contributions from Parent	0	80
Proceeds from (Payments for) Other Financing Activities	(0.1)	0
Net cash used in financing activities	(48.5)	(37.1)
Cash, cash equivalents, and restricted cash:
Restricted Cash and Cash Equivalents	32
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(34.2)	7.1
Supplemental cash flow information:
Interest paid, net of amounts capitalized	10.8	17
Income Taxes Paid, Net	19	8.3
Non-cash financing and investing activities:
Accruals for capital expenditures	2	7.2
Other Operating Income (Expense) [Member]
Adjustments to reconcile net income to net cash from operating activities:
Impairment of Long-Lived Assets Held-for-use	0	2.8
Gain (Loss) on Disposition of Business	$ 0	$ 11.7

Statement of Equity Statement

Statement of Equity Statement - USD ($) $ in Millions	Total	Common Stock [Member]	Other Additional Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]	Subsidiaries [Member]	Subsidiaries [Member]Common Stock [Member]	Subsidiaries [Member]Other Additional Capital [Member]	Subsidiaries [Member]AOCI Attributable to Parent [Member]	Subsidiaries [Member]Retained Earnings [Member]	Subsidiaries [Member]Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (584.3)	$ 0	$ 2,330.4	$ 0.8	$ (2,915.5)		$ 330.7	$ 0.4	$ 685.8	$ (36.2)	$ (319.3)
Other Comprehensive Income (Loss), Net of Tax				3.3						1.1
Net Income (Loss) Attributable to Parent					16.9						15.7
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	20.2						16.8
Non-cash capital contribution	44.6		44.6
Stockholders' Equity, Other	0			(1)	1		(0.4)		(0.3)	(1.1)	1
Dividends, Common Stock, Cash							(23.8)		(23.8)
Proceeds from Contributions from Parent							(80)		80
Other Comprehensive Income (Loss), Net of Tax	3						2.5
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	44.4						64.4
Non-cash capital contribution	30.2
Proceeds from Contributions from Parent							(80)
AOCI reclassed to Retained Earnings before tax | Adjustments for New Accounting Pronouncement [Member]	1.6						1.7
AOCI reclassed to Retained Earnings, net of tax | Adjustments for New Accounting Pronouncement [Member]	1						1.1
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(519.5)	$ 0	2,375	3.1	(2,897.6)		403.3	$ 0.4	741.7	(36.2)	(302.6)
Other Comprehensive Income (Loss), Net of Tax				(0.3)			0.8
Net Income (Loss) Attributable to Parent					3.5		15
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	3.2						15.8
Non-cash capital contribution	(17.9)		(17.9)
Stockholders' Equity, Other	$ 0.1		0.1
Common Stock, Shares Authorized	1,500
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (534.1)	$ 0	2,357.2	2.8	(2,894.1)		419.1	$ 0.4	741.7	(35.4)	(287.6)
Other Comprehensive Income (Loss), Net of Tax	0						0.6
Net Income (Loss) Attributable to Parent	21						31.2
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	21						31.8
Non-cash capital contribution	3.5		3.5
Stockholders' Equity, Other	0.1		0.1				0.1		0.1
Dividends, Common Stock, Cash							$ (20)		(20)
Common stock, par value (in USD per share)							$ 0.01
Common Stock, Shares Authorized							50,000,000
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (509.5)	$ 0	2,360.8	2.8	(2,873.1)		$ 431	$ 0.4	721.8	(34.8)	(256.4)
Common stock, par value (in USD per share)							$ 0.01
Common Stock, Shares Authorized	1,500						50,000,000
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (471.7)	$ 0	2,370.5	2.2	(2,844.4)		$ 445.3	$ 0.4	711.8	(35.3)	(231.6)
Other Comprehensive Income (Loss), Net of Tax				(0.4)						0.4
Net Income (Loss) Attributable to Parent					42.1						29
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	41.7						29.4
Non-cash capital contribution	1.5		1.5
Stockholders' Equity, Other	0.1		0.1				(0.3)				(0.3)
Other Comprehensive Income (Loss), Net of Tax	(2.2)					$ (2.3)	1.1					$ (1)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	59.2						104.8
Non-cash capital contribution	2.7
Proceeds from Contributions from Parent							0
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(428.4)	$ 0	2,372.1	1.8	(2,802.3)		474.4	$ 0.4	711.8	(34.9)	(202.9)
Other Comprehensive Income (Loss), Net of Tax				(0.8)						(0.9)
Net Income (Loss) Attributable to Parent					(16.1)						29.8
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(16.9)						28.9
Non-cash capital contribution	(1.5)		(1.5)
Proceeds from Contributions from Parent							70		(70)
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(446.8)	$ 0	2,370.6	1	(2,818.4)		433.3	$ 0.4	641.8	(35.8)	(173.1)
Other Comprehensive Income (Loss), Net of Tax	(1)						1.6
Net Income (Loss) Attributable to Parent	35.4						44.9
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	34.4						46.5
Non-cash capital contribution	2.7		2.7
Stockholders' Equity, Other	$ 0.1		0.1				0		(0.1)		0.1
Dividends, Common Stock, Cash							$ (20)		(20)
Common stock, par value (in USD per share)							$ 0.01
Common Stock, Shares Authorized	1,500						50,000,000
Shares, Issued		1						41,172,173
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (409.6)	$ 0	$ 2,373.4	$ 0	$ (2,783)		$ 459.8	$ 0.4	$ 621.9	$ (34.2)	$ (128.3)

Overview and Summary of Signifi

Overview and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Significant Accounting Policies [Line Items]
Overview and Summary of Significant Accounting Policies	Overview and Summary of Significant Accounting Policies Description of Business DPL is a regional energy company organized in 1985 under the laws of Ohio. DPL has one reportable segment: the Utility segment. See Note 11 – Business Segments for more information relating to this reportable segment. The terms “we,” “us,” “our” and “ours” are used to refer to DPL and its subsidiaries. DPL is an indirectly wholly-owned subsidiary of AES. DP&L , a wholly-owned subsidiary of DPL , is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service; however, retail transmission and distribution services are still regulated. DP&L has the exclusive right to provide such transmission and distribution services to approximately 524,000 customers located in West Central Ohio. Additionally, DP&L provides retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 - square mile area of West Central Ohio. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. Following the issuance of the DRO in September 2018 and the resulting changes to the decoupling rider effective January 1, 2019, DP&L's distribution sales are primarily impacted by customer growth within our service territory. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DPL’s other primary subsidiaries include MVIC and AES Ohio Generation. MVIC is our captive insurance company that provides insurance services to DPL and our other subsidiaries. AES Ohio Generation's only operating asset is an undivided interest in Conesville. AES Ohio Generation sells all of its energy and capacity into the wholesale market. DPL's subsidiaries are all wholly-owned. DPL also has a wholly-owned business trust, DPL Capital Trust II, formed for the purpose of issuing trust capital securities to investors. DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DPL and its subsidiaries employed 653 people as of September 30, 2019 , of which 642 were employed by DP&L. Approximately 57% of all DPL employees are under a collective bargaining agreement, which expires October 31, 2020 . Financial Statement Presentation DPL’s Condensed Consolidated Financial Statements include the accounts of DPL and its wholly-owned subsidiaries except for DPL Capital Trust II, which is not consolidated, consistent with the provisions of GAAP. As of September 30, 2019 , AES Ohio Generation has an undivided ownership interest in one coal-fired generating facility, which is included in the financial statements at a carrying value of zero as it has been fully impaired. Operating revenues and expenses of this facility are included on a pro rata basis in the corresponding lines in the Condensed Consolidated Statements of Operations. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. All material intercompany accounts and transactions are eliminated in consolidation. We have evaluated subsequent events through the date this report is issued. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2018 . In the opinion of our management, the Condensed Consolidated Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of September 30, 2019 ; our results of operations for the three and nine months ended September 30, 2019 and 2018 , our cash flows for the nine months ended September 30, 2019 and 2018 and the changes in our equity for the three and nine months ended September 30, 2019 and 2018 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, interim results for the three and nine months ended September 30, 2019 may not be indicative of our results that will be realized for the full year ending December 31, 2019 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: recognition of revenue including unbilled revenues, the carrying value of property, plant and equipment; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; and assets and liabilities related to employee benefits. Cash, Cash Equivalents, and Restricted Cash The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Consolidated Balance Sheet that reconcile to the total of such amounts as shown on the Condensed Consolidated Statements of Cash Flows: $ in millions September 30, 2019 December 31, 2018 Cash and cash equivalents $ 36.8 $ 90.5 Restricted cash 17.6 21.2 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 54.4 $ 111.7 Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended September 30, 2019 and 2018 were $13.0 million and $13.8 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2019 and 2018 were $37.3 million and $39.2 million, respectively. New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed consolidated financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Consolidated Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed consolidated financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $70.2 million in gross trade accounts receivable.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Overview and Summary of Significant Accounting Policies	Overview and Summary of Significant Accounting Policies Description of Business DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service; however, retail transmission and distribution services are still regulated. DP&L has the exclusive right to provide such transmission and distribution services to approximately 524,000 customers located in West Central Ohio. Additionally, DP&L provides retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 - square mile area of West Central Ohio. As a result of Generation Separation, DP&L now only has one reportable segment, the Utility segment. In addition to DP&L's electric transmission and distribution businesses, the Utility segment includes revenues and costs associated with DP&L's investment in OVEC and the historical results of DP&L’s Beckjord and Hutchings Coal generating facilities, which have either been closed or sold. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. Following the issuance of the DRO in September 2018 and the resulting changes to the decoupling rider effective January 1, 2019, DP&L's distribution sales are primarily impacted by customer growth within our service territory. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DP&L is a subsidiary of DPL. The terms “we,” “us,” “our” and “ours” are used to refer to DP&L . DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DP&L employed 642 people as of September 30, 2019 . Approximately 58% of DP&L employees are under a collective bargaining agreement, which expires October 31, 2020 . Financial Statement Presentation DP&L does not have any subsidiaries. We have evaluated subsequent events through the date this report is issued. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2018 . In the opinion of our management, the Condensed Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of September 30, 2019 ; our results of operations for the three and nine months ended September 30, 2019 and 2018 , our cash flows for the nine months ended September 30, 2019 and 2018 and the changes in our equity for the three and nine months ended September 30, 2019 and 2018 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, interim results for the three and nine months ended September 30, 2019 may not be indicative of our results that will be realized for the full year ending December 31, 2019 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: recognition of revenue including unbilled revenues, the carrying value of property, plant and equipment; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; and assets and liabilities related to employee benefits. Cash, Cash Equivalents, and Restricted Cash The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Balance Sheet that reconcile to the total of such amounts as shown on the Condensed Statements of Cash Flows: $ in millions September 30, 2019 December 31, 2018 Cash and cash equivalents $ 14.4 $ 45.0 Restricted cash 17.6 21.2 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 32.0 $ 66.2 Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended September 30, 2019 and 2018 were $13.0 million and $13.8 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2019 and 2018 were $37.3 million and $39.2 million, respectively. New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $72.1 million in gross trade accounts receivable.

Supplemental Financial Informat

Supplemental Financial Information	9 Months Ended
	Sep. 30, 2019
Supplemental Financial Information [Line Items]
Supplemental Financial Information	Supplemental Financial Information Accounts receivable and Inventories are as follows at September 30, 2019 and December 31, 2018 : September 30, December 31, $ in millions 2019 2018 Accounts receivable, net: Customer receivables $ 51.1 $ 55.8 Unbilled revenue 15.2 16.8 Amounts due from affiliates 0.2 — Due from PJM transmission enhancement settlement 2.4 16.5 Other 1.3 2.3 Provision for uncollectible accounts (0.4 ) (0.9 ) Total accounts receivable, net $ 69.8 $ 90.5 Inventories, at average cost: Fuel and limestone $ 3.0 $ 1.9 Materials and supplies 10.0 8.3 Other — 0.5 Total inventories, at average cost $ 13.0 $ 10.7 Accumulated Other Comprehensive Income / (Loss) The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and nine months ended September 30, 2019 and 2018 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Gains and losses on cash flow hedges (Note 5): Interest expense $ (0.3 ) $ (0.3 ) $ (0.9 ) $ (0.9 ) Income tax benefit / (expense) (0.1 ) 0.1 — 0.3 Net of income taxes (0.4 ) (0.2 ) (0.9 ) (0.6 ) Loss from discontinued operations — — — 4.3 Income tax benefit from discontinued operations (0.4 ) — (0.4 ) (1.5 ) Net of income taxes (0.4 ) — (0.4 ) 2.8 Amortization of defined benefit pension items (Note 8): Other expense 0.1 0.2 0.2 0.5 Income tax benefit (0.1 ) (0.1 ) (0.1 ) (0.1 ) Net of income taxes — 0.1 0.1 0.4 Total reclassifications for the period, net of income taxes $ (0.8 ) $ (0.1 ) $ (1.2 ) $ 2.6 The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the nine months ended September 30, 2019 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligation Total Balance at January 1, 2019 $ 17.0 $ (14.8 ) $ 2.2 Other comprehensive loss before reclassifications (1.0 ) — (1.0 ) Amounts reclassified from AOCI to earnings (1.3 ) 0.1 (1.2 ) Net current period other comprehensive income / (loss) (2.3 ) 0.1 (2.2 ) Balance at September 30, 2019 $ 14.7 $ (14.7 ) $ — Operating expenses - other Operating expenses - other generally includes gains or losses on asset sales or dispositions, insurance recoveries, gains or losses on the sale of businesses and other expense or income from miscellaneous transactions. The components of Operating expenses - other are summarized as follows: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Loss on disposal and sale of businesses $ — $ — $ — $ 11.7 Fixed-asset impairment — 1.6 — 2.8 Other — — 0.9 0.1 Net other expense / (income) $ — $ 1.6 $ 0.9 $ 14.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Supplemental Financial Information	Supplemental Financial Information Accounts receivable and Inventories are as follows at September 30, 2019 and December 31, 2018 : September 30, December 31, $ in millions 2019 2018 Accounts receivable, net: Customer receivables $ 50.0 $ 53.3 Unbilled revenue 15.2 16.8 Amounts due from affiliates 3.2 2.3 Due from PJM transmission enhancement settlement 2.4 16.5 Other 1.3 2.4 Provision for uncollectible accounts (0.4 ) (0.9 ) Total accounts receivable, net $ 71.7 $ 90.4 Inventories, at average cost: Materials and supplies $ 9.8 $ 7.1 Other — 0.6 Total inventories, at average cost $ 9.8 $ 7.7 Accumulated Other Comprehensive Income / (Loss) The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and nine months ended September 30, 2019 and 2018 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Gains and losses on cash flow hedges (Note 5): Interest expense $ — $ (0.3 ) $ (0.1 ) $ (1.1 ) Income tax expense — 0.1 — 0.6 Net of income taxes — (0.2 ) (0.1 ) (0.5 ) Amortization of defined benefit pension items (Note 8): Other expense 0.8 1.0 2.6 3.2 Income tax expense / (benefit) 0.9 (0.2 ) (0.5 ) (0.7 ) Net of income taxes 1.7 0.8 2.1 2.5 Total reclassifications for the period, net of income taxes $ 1.7 $ 0.6 $ 2.0 $ 2.0 The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the nine months ended September 30, 2019 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligation Total Balance at January 1, 2019 $ 0.6 $ (35.9 ) $ (35.3 ) Other comprehensive loss before reclassifications (0.9 ) — (0.9 ) Amounts reclassified from AOCI to earnings (0.1 ) 2.1 2.0 Net current period other comprehensive income / (loss) (1.0 ) 2.1 1.1 Balance at September 30, 2019 $ (0.4 ) $ (33.8 ) $ (34.2 )

Regulatory Matters (Notes)

Regulatory Matters (Notes)	9 Months Ended
	Sep. 30, 2019
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters DMR On October 20, 2017, the PUCO approved DP&L’s 2017 ESP. On January 7, 2019, the Ohio Consumers' Counsel appealed to the Supreme Court of Ohio the 2017 ESP with respect to the bypassability of the Reconciliation Rider and the exclusion of the DMR from the SEET. That proceeding has been stayed pending an appeal in a related case involving another utility. Pursuant to the 2017 ESP, on January 22, 2019, DP&L filed a request with the PUCO for a two-year extension of its DMR through October 2022, in the proposed amount of $199.0 million for each of the two additional years. The extension request was set at a level expected to reduce debt obligations at both DP&L and DPL and to position DP&L to make capital expenditures to maintain and modernize its electric grid. DP&L’s DMP investments are contingent upon the PUCO approving the two-year extension of its DMR. A rehearing process in DP&L's 2017 ESP case, including the DMR, remains pending. On August 1, 2019, DP&L filed a supplemental brief with the PUCO focused on the applicability of a recent court decision involving another Ohio utility’s DMR which is similar to, but not identical to, DP&L’s DMR. Ohio House Bill 6 On July 23, 2019, the Governor of Ohio signed Ohio House Bill 6, which, among other things, does the following: • beginning January 1, 2020, replaces DP&L’s non-bypassable Reconciliation Rider, permitting DP&L to defer, recover or credit the net proceeds from selling energy and capacity received as part of DP&L’s interest in OVEC and its OVEC-related costs through 2023, with a non-bypassable recovery mechanism for recovery of prudently incurred OVEC costs through 2030; • eliminates the annual energy efficiency targets for Ohio utilities after 2020; and • allows Ohio utilities to construct customer-sited renewable generation for mercantile customers or groups of mercantile customers, the costs of which may only be recovered from those customers. Regulatory impact of tax reform On January 10, 2018, the PUCO initiated a proceeding to consider the impacts of the TCJA to determine the appropriate course of action to pass benefits resulting from the legislation on to ratepayers. The PUCO also directed Ohio utilities to record deferred liabilities for the estimated reduction in federal income tax resulting from the TCJA beginning January 1, 2018. Beginning October 1, 2018, the new distribution rates approved in the DRO include the impacts of the decrease in current federal income taxes as a result of the TCJA. Under the terms of the stipulation approved in the DRO, DP&L agreed to file an application at the PUCO to refund eligible excess accumulated deferred income taxes and any related regulatory liability over a ten-year period. DP&L made such a filing on March 1, 2019 . DP&L negotiated a unanimous stipulation with the parties in the proceeding, agreeing to return a total of $65.1 million , $83.2 million when including taxes associated with the refunds. This stipulation was approved by the PUCO on September 26, 2019. See Note 7 – Income Taxes for additional information. In connection with this stipulation, we reduced our long-term regulatory liability related to deferred income taxes by $23.4 million .
Subsidiaries [Member]
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters DMR On October 20, 2017, the PUCO approved DP&L’s 2017 ESP. On January 7, 2019, the Ohio Consumers' Counsel appealed to the Supreme Court of Ohio the 2017 ESP with respect to the bypassability of the Reconciliation Rider and the exclusion of the DMR from the SEET. That proceeding has been stayed pending an appeal in a related case involving another utility. Pursuant to the 2017 ESP, on January 22, 2019, DP&L filed a request with the PUCO for a two-year extension of its DMR through October 2022, in the proposed amount of $199.0 million for each of the two additional years. The extension request was set at a level expected to reduce debt obligations at both DP&L and DPL and to position DP&L to make capital expenditures to maintain and modernize its electric grid. DP&L’s DMP investments are contingent upon the PUCO approving the two-year extension of its DMR. A rehearing process in DP&L's 2017 ESP case, including the DMR, remains pending. On August 1, 2019, DP&L filed a supplemental brief with the PUCO focused on the applicability of a recent court decision involving another Ohio utility’s DMR which is similar to, but not identical to, DP&L’s DMR. Ohio House Bill 6 On July 23, 2019, the Governor of Ohio signed Ohio House Bill 6, which, among other things, does the following: • beginning January 1, 2020, replaces DP&L’s non-bypassable Reconciliation Rider, permitting DP&L to defer, recover or credit the net proceeds from selling energy and capacity received as part of DP&L’s interest in OVEC and its OVEC-related costs through 2023, with a non-bypassable recovery mechanism for recovery of prudently incurred OVEC costs through 2030; • eliminates the annual energy efficiency targets for Ohio utilities after 2020; and • allows Ohio utilities to construct customer-sited renewable generation for mercantile customers or groups of mercantile customers, the costs of which may only be recovered from those customers. Regulatory impact of tax reform On January 10, 2018, the PUCO initiated a proceeding to consider the impacts of the TCJA to determine the appropriate course of action to pass benefits resulting from the legislation on to ratepayers. The PUCO also directed Ohio utilities to record deferred liabilities for the estimated reduction in federal income tax resulting from the TCJA beginning January 1, 2018. Beginning October 1, 2018, the new distribution rates approved in the DRO include the impacts of the decrease in current federal income taxes as a result of the TCJA. Under the terms of the stipulation approved in the DRO, DP&L agreed to file an application at the PUCO to refund eligible excess accumulated deferred income taxes and any related regulatory liability over a ten-year period. DP&L made such a filing on March 1, 2019 . DP&L negotiated a unanimous stipulation with the parties in the proceeding, agreeing to return a total of $65.1 million , $83.2 million when including taxes associated with the refunds. This stipulation was approved by the PUCO on September 26, 2019. See Note 7 – Income Taxes for additional information. In connection with this stipulation, we reduced our long-term regulatory liability related to deferred income taxes by $23.4 million .

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	Fair Value The fair value of current financial assets and liabilities, debt service reserves and other deposits approximate their reported carrying amounts. The estimated fair values of our assets and liabilities have been determined using available market information. By virtue of these amounts being estimates and based on hypothetical transactions to sell assets or transfer liabilities, the use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. For further information on our valuation techniques and policies, see Note 5— Fair Value in Item 8.— Financial Statements and Supplementary Data of our Form 10-K. The following table presents the fair value, carrying value and cost of our non-derivative instruments at September 30, 2019 and December 31, 2018 . Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities . September 30, 2019 December 31, 2018 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.4 $ 0.4 Equity securities 2.3 3.9 2.4 3.5 Debt securities 4.1 4.1 4.1 4.0 Hedge funds 0.1 0.1 0.1 0.1 Tangible assets 0.1 0.1 0.1 0.1 Total Assets $ 6.8 $ 8.4 $ 7.1 $ 8.1 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 1,362.9 $ 1,451.3 $ 1,475.9 $ 1,519.6 These financial instruments are not subject to master netting agreements or collateral requirements and as such are presented in the Condensed Consolidated Balance Sheet at their gross fair value, except for Long-term debt, which is presented at amortized carrying value. We did not have any transfers of the fair values of our financial instruments between Level 1, Level 2 or Level 3 of the fair value hierarchy during the nine months ended September 30, 2019 or 2018 . Master Trust Assets DP&L established a Master Trust to hold assets that could be used for the benefit of employees participating in employee benefit plans and these assets are not used for general operating purposes. On January 1, 2018, AOCI of $1.6 million ( $1.0 million net of tax) was reversed to Accumulated Deficit and all future changes to fair value on the Master Trust Assets will be included in income in the period that the changes occur. Changes to fair value were not material for the nine months ended September 30, 2019 or 2018 . These assets are primarily comprised of open-ended mutual funds, which are valued using the net asset value per unit. These investments are recorded at fair value within Other deferred assets on the Condensed Consolidated Balance Sheets and classified as available for sale. Long-term debt The fair value of debt is based on current public market prices for disclosure purposes only. Unrealized gains or losses are not recognized in the financial statements as long-term debt is presented at carrying value, net of unamortized premium or discount and unamortized deferred financing costs in the financial statements. The long-term debt amounts include the current portion payable in the next twelve months and have maturities that range from 2020 to 2061 . The fair value of assets and liabilities at September 30, 2019 and December 31, 2018 and the respective category within the fair value hierarchy for DPL is as follows: $ in millions Fair value at September 30, 2019 (a) Fair value at December 31, 2018 (a) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Master Trust assets Money market funds $ 0.2 $ — $ — $ 0.2 $ 0.4 $ — $ — $ 0.4 Equity securities — 3.9 — 3.9 — 3.5 — 3.5 Debt securities — 4.1 — 4.1 — 4.0 — 4.0 Hedge funds — 0.1 — 0.1 — 0.1 — 0.1 Tangible assets — 0.1 — 0.1 — 0.1 — 0.1 Total Master Trust assets 0.2 8.2 — 8.4 0.4 7.7 — 8.1 Derivative assets Interest rate hedges — 0.2 — 0.2 — 1.5 — 1.5 Total Derivative assets — 0.2 — 0.2 — 1.5 — 1.5 Total Assets $ 0.2 $ 8.4 $ — $ 8.6 $ 0.4 $ 9.2 $ — $ 9.6 Liabilities Long-term debt $ — $ 1,433.7 $ 17.6 $ 1,451.3 $ — $ 1,501.9 $ 17.7 $ 1,519.6 Total Liabilities $ — $ 1,433.7 $ 17.6 $ 1,451.3 $ — $ 1,501.9 $ 17.7 $ 1,519.6 (a) Includes credit valuation adjustment Our financial instruments are valued using the market approach in the following categories: • Level 1 inputs are used for money market accounts that are considered cash equivalents. The fair value is determined by reference to quoted market prices and other relevant information generated by market transactions. • Level 2 inputs are used to value derivatives such as interest rate hedge contracts which are valued using a benchmark interest rate. Other Level 2 assets include open-ended mutual funds in the Master Trust, which are valued using the end of day NAV per unit. • Level 3 inputs such as certain debt balances are considered a Level 3 input because the notes are not publicly traded. Our long-term debt is fair valued for disclosure purposes only. All of the inputs to the fair value of our derivative instruments are from quoted market prices. Our long-term debt is fair valued for disclosure purposes only and most of the fair values are determined using quoted market prices in inactive markets. These fair value inputs are considered Level 2 in the fair value hierarchy. As the Wright-Patterson Air Force Base note is not publicly traded, fair value is assumed to equal carrying value. These fair value inputs are considered Level 3 in the fair value hierarchy as there are no observable inputs. Additional Level 3 disclosures are not presented since our long-term debt is not recorded at fair value.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	Fair Value The fair value of current financial assets and liabilities, debt service reserves and other deposits approximate their reported carrying amounts. The estimated fair values of our assets and liabilities have been determined using available market information. By virtue of these amounts being estimates and based on hypothetical transactions to sell assets or transfer liabilities, the use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. For further information on our valuation techniques and policies, see Note 5— Fair Value in Item 8.— Financial Statements and Supplementary Data of our Form 10-K. The following table presents the fair value, carrying value and cost of our non-derivative instruments at September 30, 2019 and December 31, 2018 . Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities . September 30, 2019 December 31, 2018 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.4 $ 0.4 Equity securities 2.3 3.9 2.4 3.5 Debt securities 4.1 4.1 4.1 4.0 Hedge funds 0.1 0.1 0.1 0.1 Tangible assets 0.1 0.1 0.1 0.1 Total assets $ 6.8 $ 8.4 $ 7.1 $ 8.1 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 574.2 $ 631.0 $ 586.1 $ 593.8 These financial instruments are not subject to master netting agreements or collateral requirements and as such are presented in the Condensed Balance Sheet at their gross fair value, except for Long-term debt, which is presented at amortized carrying value. We did not have any transfers of the fair values of our financial instruments between Level 1, Level 2 or Level 3 of the fair value hierarchy during the nine months ended September 30, 2019 or 2018 . Master Trust Assets DP&L established a Master Trust to hold assets that could be used for the benefit of employees participating in employee benefit plans and these assets are not used for general operating purposes. On January 1, 2018, AOCI of $1.7 million ( $1.1 million net of tax) was reversed to Accumulated Deficit and all future changes to fair value on the Master Trust Assets will be included in income in the period that the changes occur. Changes to fair value were not material for the nine months ended September 30, 2019 or 2018 . These assets are primarily comprised of open-ended mutual funds, which are valued using the net asset value per unit. These investments are recorded at fair value within Other deferred assets on the Condensed Balance Sheets and classified as available for sale. Long-term debt The fair value of debt is based on current public market prices for disclosure purposes only. Unrealized gains or losses are not recognized in the financial statements as long-term debt is presented at carrying value, net of unamortized premium or discount and unamortized deferred financing costs in the financial statements. The long-term debt amounts include the current portion payable in the next twelve months and have maturities that range from 2020 to 2061 . The fair value of assets and liabilities at September 30, 2019 and December 31, 2018 and the respective category within the fair value hierarchy for DP&L is as follows: $ in millions Fair value at September 30, 2019 (a) Fair value at December 31, 2018 (a) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Master Trust assets Money market funds $ 0.2 $ — $ — $ 0.2 $ 0.4 $ — $ — $ 0.4 Equity securities — 3.9 — 3.9 — 3.5 — 3.5 Debt securities — 4.1 — 4.1 — 4.0 — 4.0 Hedge funds — 0.1 — 0.1 — 0.1 — 0.1 Tangible assets — 0.1 — 0.1 — 0.1 — 0.1 Total Master Trust assets 0.2 8.2 — 8.4 0.4 7.7 — 8.1 Derivative assets Interest rate hedges — 0.2 — 0.2 — 1.5 — 1.5 Total derivative assets — 0.2 — 0.2 — 1.5 — 1.5 Total assets $ 0.2 $ 8.4 $ — $ 8.6 $ 0.4 $ 9.2 $ — $ 9.6 Liabilities Long-term debt $ — $ 613.4 $ 17.6 631.0 $ — $ 576.1 $ 17.7 $ 593.8 Total liabilities $ — $ 613.4 $ 17.6 $ 631.0 $ — $ 576.1 $ 17.7 $ 593.8 (a) Includes credit valuation adjustment Our financial instruments are valued using the market approach in the following categories: • Level 1 inputs are used for money market accounts that are considered cash equivalents. The fair value is determined by reference to quoted market prices and other relevant information generated by market transactions. • Level 2 inputs are used to value derivatives such as interest rate hedge contracts which are valued using a benchmark interest rate. Other Level 2 assets include open-ended mutual funds in the Master Trust, which are valued using the end of day NAV per unit. • Level 3 inputs such as certain debt balances are considered a Level 3 input because the notes are not publicly traded. Our long-term debt is fair valued for disclosure purposes only. All of the inputs to the fair value of our derivative instruments are from quoted market prices. Our long-term debt is fair valued for disclosure purposes only and most of the fair values are determined using quoted market prices in inactive markets. These fair value inputs are considered Level 2 in the fair value hierarchy. As the Wright-Patterson Air Force Base note is not publicly traded, fair value is assumed to equal carrying value. These fair value inputs are considered Level 3 in the fair value hierarchy as there are no observable inputs. Additional Level 3 disclosures are not presented since our long-term debt is not recorded at fair value.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities In the normal course of business, DPL enters into interest rate hedges to manage the interest rate risk of our variable rate debt. All of our derivative instruments are used for risk management purposes and are designated as cash flow hedges if they qualify under FASC 815 for accounting purposes. In prior periods, we have used commodity derivatives principally to manage the risk of changes in market prices for commodities. Cash Flow Hedges As part of our risk management processes, we identify the relationships between hedging instruments and hedged items, as well as the risk management objective and strategy for undertaking various hedge transactions. The fair values of cash flow hedges determined by current public market prices will continue to fluctuate with changes in market prices up to contract expiration. With the adoption of ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities effective January 1, 2019, we will no longer be required to calculate effectiveness and thus the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item in the period in which it settles. As of September 30, 2019 , we have two interest rate swaps to hedge the variable interest on our $140.0 million variable interest rate tax-exempt First Mortgage Bonds. The interest rate swaps have a combined notional amount of $140.0 million and settle monthly based on a one-month LIBOR. On March 29, 2018, we settled $60.0 million of these interest rate swaps due to the partial repayment of the underlying debt and a gain of $0.8 million was recorded as a reduction to interest expense. Since the swap was partially settled, the remaining swaps were de-designated and then re-designated with a new hypothetical derivative. The AOCI associated with the remaining swaps will be amortized out of AOCI into interest expense over the remaining life of the underlying debt. We had previously entered into interest rate derivative contracts to manage interest rate exposure related to anticipated borrowings of fixed-rate debt. These interest rate derivative contracts were settled in 2013 and we continue to amortize amounts out of AOCI into interest expense. The following tables provide information concerning gains or losses recognized in AOCI for the cash flow hedges for the three and nine months ended September 30, 2019 and 2018 : Three months ended Three months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gains in AOCI $ 0.4 $ 15.3 $ — $ 17.4 Net gains / (losses) associated with current period hedging transactions — (0.2 ) — 0.1 Net gains reclassified to earnings Interest expense — (0.4 ) — (0.2 ) (Income) / loss from discontinued operations (0.4 ) — — — Ending accumulated derivative gains in AOCI $ — $ 14.7 $ — $ 17.3 Nine months ended Nine months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gains / (losses) in AOCI $ 0.4 $ 16.6 $ (2.8 ) $ 17.5 Net gains / (losses) associated with current period hedging transactions — (1.0 ) — 0.4 Net (gains) / losses reclassified to earnings Interest expense — (0.9 ) — (0.6 ) (Income) / loss from discontinued operations (0.4 ) — 2.8 — Ending accumulated derivative gains in AOCI $ — $ 14.7 $ — $ 17.3 Portion expected to be reclassified to earnings in the next twelve months $ (1.2 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 11 Net gains or losses associated with the ineffective portion of the hedging transactions were immaterial in the prior year period presented. Financial Statement Effect DPL has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The fair value derivative position of DPL's interest rate swaps are as follows: Fair Values of Derivative Instruments at September 30, 2019 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swap Designated $ 0.2 $ — $ — $ 0.2 Total assets $ 0.2 $ — $ — $ 0.2 (a) Includes credit valuation adjustment. Fair Values of Derivative Instruments at December 31, 2018 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swaps Designated $ 0.9 $ — $ — $ 0.9 Long-term derivative positions (presented in Other non-current assets) Interest rate swaps Designated 0.6 — — 0.6 Total assets $ 1.5 $ — $ — $ 1.5 (a) Includes credit valuation adjustment. Any prior year ineffectiveness on the interest rate hedges and the monthly settlement of the interest rate hedges is recorded in interest expense within the Condensed Consolidated Statements of Operations.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities In the normal course of business, DP&L enters into interest rate hedges to manage the interest rate risk of our variable rate debt. All of our derivative instruments are used for risk management purposes and are designated as cash flow hedges if they qualify under FASC 815 for accounting purposes. In prior periods, we have used commodity derivatives principally to manage the risk of changes in market prices for commodities. Cash Flow Hedges As part of our risk management processes, we identify the relationships between hedging instruments and hedged items, as well as the risk management objective and strategy for undertaking various hedge transactions. The fair values of cash flow hedges determined by current public market prices will continue to fluctuate with changes in market prices up to contract expiration. With the adoption of ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities effective January 1, 2019, we will no longer be required to calculate effectiveness and thus the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item in the period in which it settles. As of September 30, 2019 , we have two interest rate swaps to hedge the variable interest on our $140.0 million variable interest rate tax-exempt First Mortgage Bonds. The interest rate swaps have a combined notional amount of $140.0 million and settle monthly based on a one-month LIBOR. On March 29, 2018, we settled $60.0 million of these interest rate swaps due to the partial repayment of the underlying debt and a gain of $0.8 million was recorded as a reduction to interest expense. Since the swap was partially settled, the remaining swaps were de-designated and then re-designated with a new hypothetical derivative. The AOCI associated with the remaining swaps will be amortized out of AOCI into interest expense over the remaining life of the underlying debt. The following tables provide information concerning gains or losses recognized in AOCI for the cash flow hedges for the three and nine months ended September 30, 2019 and 2018 : Three months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains / (losses) in AOCI $ (0.3 ) $ 1.6 Net losses associated with current period hedging transactions (0.1 ) — Net gains reclassified to earnings Interest expense — (0.2 ) Ending accumulated derivative gains / (losses) in AOCI $ (0.4 ) $ 1.4 Nine months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains in AOCI $ 0.6 $ 1.4 Net gains / (losses) associated with current period hedging transactions (0.9 ) 0.5 Net gains reclassified to earnings Interest expense (0.1 ) (0.5 ) Ending accumulated derivative gains / (losses) in AOCI $ (0.4 ) $ 1.4 Portion expected to be reclassified to earnings in the next twelve months $ (0.2 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 11 Net gains or losses associated with the ineffective portion of the hedging transactions were immaterial in the prior year period presented. Financial Statement Effect DP&L has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The fair value derivative position of DP&L's interest rate swaps are as follows: Fair Values of Derivative Instruments at September 30, 2019 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swap Designated $ 0.2 $ — $ — $ 0.2 Total assets $ 0.2 $ — $ — $ 0.2 (a) Includes credit valuation adjustment. Fair Values of Derivative Instruments at December 31, 2018 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swaps Designated $ 0.9 $ — $ — $ 0.9 Long-term derivative positions (presented in Other non-current assets) Interest rate swaps Designated 0.6 — — 0.6 Total assets $ 1.5 $ — $ — $ 1.5 (a) Includes credit valuation adjustment. Any prior year ineffectiveness on the interest rate hedges and the monthly settlement of the interest rate hedges is recorded in interest expense within the Condensed Statements of Operations.

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2019
Debt Instrument [Line Items]
Debt Obligations	Long-term Debt The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2019 2018 Term loan - rates from 4.50% - 4.53% (a) and 4.01% - 4.60% (b) 2022 $ — $ 436.1 First Mortgage Bonds 3.95% 2049 425.0 — Tax-exempt First Mortgage Bonds - rates from 2.97% - 3.07% (a) and 1.52% - 1.92% (b) 2020 140.0 140.0 U.S. Government note 4.20% 2061 17.6 17.7 Unamortized deferred financing costs (5.7 ) (6.3 ) Unamortized debt discounts and premiums, net (2.7 ) (1.4 ) Total long-term debt at DP&L 574.2 586.1 Senior unsecured bonds 6.75% 2019 — 99.0 Senior unsecured bonds 7.25% 2021 380.0 780.0 Senior unsecured notes 4.35% 2029 400.0 — Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (5.8 ) (4.3 ) Unamortized debt discounts and premiums, net (1.1 ) (0.5 ) Total long-term debt 1,362.9 1,475.9 Less: current portion (139.6 ) (103.6 ) Long-term debt, net of current portion $ 1,223.3 $ 1,372.3 (a) Range of interest rates for the nine months ended September 30, 2019 . (b) Range of interest rates for the year ended December 31, 2018 . (c) Note payable to related party. Deferred financing costs are amortized over the remaining life of the debt using the effective interest method. Premiums or discounts on long-term debt are amortized over the remaining life of the debt using the effective interest method. Line of credit At September 30, 2019 and December 31, 2018 , DPL had outstanding borrowings on its line of credit of $38.0 million and $0.0 million, respectively. At September 30, 2019 and December 31, 2018 , DP&L had outstanding borrowings on its line of credit of $60.0 million and $0.0 million, respectively. Significant transactions On June 19, 2019, DP&L amended and restated its unsecured revolving credit facility. The revolving credit facility has a $175.0 million borrowing limit, with a $75.0 million letter of credit sublimit, a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million , a maturity date of June 2024, and a provision that provides DP&L the option to request up to two one-year extensions of the maturity date. On June 6, 2019, DP&L closed on a $425.0 million issuance of First Mortgage Bonds due 2049. These new bonds carry an interest rate of 3.95% . The proceeds of this issuance were used to repay in full the outstanding principal of $435.0 million of DP&L's variable rate Term Loan B credit agreement. On June 19, 2019, DPL amended and restated its secured revolving credit facility. The revolving credit facility has a $125.0 million borrowing limit, with a $75.0 million letter of credit sublimit, a feature that provides DPL the ability to increase the size of the facility by an additional $50.0 million , and a maturity date of June 2023. On April 17, 2019, DPL closed a $400.0 million issuance of senior unsecured notes. These notes carry an interest rate of 4.35% and mature on April 15, 2029. Proceeds from the issuance and cash on hand were used to settle a partial redemption for $400.0 million of DPL's 7.25% senior unsecured notes maturing October 15, 2021, as discussed below. After the redemption, the DPL 7.25% senior notes due in 2021 have an outstanding balance of $380.0 million . On April 8, 2019, DPL issued a Notice of Partial Redemption to the Trustee (Wells Fargo Bank N.A.) on the DPL 7.25% Senior Notes due 2021. DPL redeemed $400.0 million of the $780.0 million outstanding principal amount of these notes on May 7, 2019. These bonds were redeemed at par plus accrued interest and a make-whole premium of $41.4 million . On March 4, 2019, DPL issued a Notice of Full Redemption to the Trustee (U.S. Bank) on the DPL 6.75% Senior Notes due 2019. DPL redeemed the remaining $99.0 million outstanding principal amount of these notes on April 4, 2019. These bonds were redeemed at par plus accrued interest and a make-whole premium of $1.5 million with cash on hand. On March 30, 2018, DPL issued a Notice of Partial Redemption to the Trustee (U.S. Bank) on the DPL 6.75% Senior Notes due 2019. DPL redeemed $101.0 million of the $200.0 million outstanding principal amount of these notes at par plus accrued interest and a make-whole premium of $5.1 million on April 30, 2018 with cash on hand. On March 30, 2018, DP&L commenced a redemption of $60.0 million of outstanding tax exempt First Mortgage Bonds due 2020 at par value (plus accrued and unpaid interest). These bonds were redeemed at par plus accrued interest on April 30, 2018 with cash on hand. On March 27, 2018, DPL made a $70.0 million prepayment to eliminate the outstanding balance of its bank term loan in full. As of March 31, 2018, the term loan was fully paid off. Long-term debt covenants and restrictions DPL’s revolving credit agreement has two financial covenants. The first financial covenant, a Total Debt to EBITDA ratio, is calculated at the end of each fiscal quarter by dividing total debt at the end of the current quarter by consolidated EBITDA for the four prior fiscal quarters. The ratio in the agreement is not to exceed 7.00 to 1.00. As of September 30, 2019 , this financial covenant was met with a ratio of 5.68 to 1.00. The second financial covenant is an EBITDA to Interest Expense ratio that is calculated, at the end of each fiscal quarter, by dividing EBITDA for the four prior fiscal quarters by the consolidated interest charges for the same period. The ratio, per the agreement, is to be not less than 2.25 to 1.00. As of September 30, 2019 , this financial covenant was met with a ratio of 2.99 to 1.00. DPL’s secured revolving credit agreement also restricts dividend payments from DPL to AES, such that DPL cannot make dividend payments unless at the time of, and/or as a result of the distribution, (i) DPL’s leverage ratio does not exceed 0.67 to 1.00 and DPL’s interest coverage ratio is not less than 2.50 to 1.00 or, if such ratios are not within the parameters, (ii) DPL’s senior long-term debt rating from two of the three major credit rating agencies is at least investment grade. DPL is also restricted from making dividend and tax sharing payments from DPL to AES per its 2017 ESP. This order restricts dividend payments from DPL to AES during the term of the 2017 ESP and restricts tax sharing payments from DPL to AES during the term of the DMR. DP&L’s Bond Purchase and Covenants Agreement (financing document entered into in connection with the sale of $200.0 million of variable rate tax-exempt First Mortgage Bonds, dated as of August 1, 2015) has two financial covenants. The first measures Total Debt to Total Capitalization and is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. DP&L’s Total Debt to Total Capitalization ratio shall not be greater than 0.65 to 1.00. Except that, after Generation Separation and the twelve-month period following (October 1, 2017 to September 30, 2018) the ratio shall be a) increased to 0.75 to 1.00 or b) suspended if DP&L’s long-term indebtedness is less than or equal to $750.0 million . Additionally, this covenant shall be suspended any time after separation during which DP&L maintains a rating of BBB- (or in the case of Moody’s Investors Service, Inc. Baa3) or higher with a stable outlook from at least one of Fitch Investors Service Inc., Standard & Poor’s Ratings Services or Moody’s Investors Service, Inc. The Total Debt to Capitalization covenant is calculated as the sum of DP&L’s current and long-term portion of debt, divided by the total of DP&L’s net worth and total debt. As of September 30, 2019 , DP&L's ratings meet those requirements and this covenant is suspended for the quarter ended September 30, 2019 . The second financial covenant measures EBITDA to Interest Expense. The Total Consolidated EBITDA to Consolidated Interest Charges ratio is calculated, at the end of each fiscal quarter, by dividing consolidated EBITDA for the four prior fiscal quarters by the consolidated interest charges for the same period. The ratio, per the agreement, is to be not less than 2.50 to 1.00. This financial covenant was met with a ratio of 9.36 to 1.00 as of September 30, 2019 . DP&L's unsecured revolving credit facility has one financial covenant. The covenant measures Total Debt to Total Capitalization and is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. DP&L’s Total Debt to Total Capitalization ratio shall not be greater than 0.67 to 1.00. This financial covenant was met with a ratio of 0.58 to 1.00 as of September 30, 2019 . As of September 30, 2019 , DPL and DP&L were in compliance with all debt covenants, including the financial covenants described above. DP&L does not have any meaningful restrictions in its debt financing documents prohibiting dividends to its parent, DPL. Substantially all property, plant & equipment of DP&L is subject to the lien of the mortgage securing DP&L’s First and Refunding Mortgage.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Obligations	Long-term Debt The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2019 2018 Term loan - rates from 4.50% - 4.53% (a) and 4.01% - 4.60% (b) 2022 $ — $ 436.1 First Mortgage Bonds 3.95% 2049 425.0 — Tax-exempt First Mortgage Bonds - rates from 2.97% - 3.07% (a) and 1.52% - 1.92% (b) 2020 140.0 140.0 U.S. Government note 4.20% 2061 17.6 17.7 Unamortized deferred financing costs (5.7 ) (6.3 ) Unamortized debt discounts and premiums, net (2.7 ) (1.4 ) Total long-term debt 574.2 586.1 Less: current portion (139.6 ) (4.6 ) Long-term debt, net of current portion $ 434.6 $ 581.5 (a) Range of interest rates for the nine months ended September 30, 2019 . (b) Range of interest rates for the year ended December 31, 2018 . Deferred financing costs are amortized over the remaining life of the debt using the effective interest method. Premiums or discounts on long-term debt are amortized over the remaining life of the debt using the effective interest method. Line of credit At September 30, 2019 and December 31, 2018 , DP&L had outstanding borrowings on its line of credit of $60.0 million and $0.0 million, respectively. Significant transactions On June 19, 2019, DP&L amended and restated its unsecured revolving credit facility. The revolving credit facility has a $175.0 million borrowing limit, with a $75.0 million letter of credit sublimit, a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million , a maturity date of June 2024, and a provision that provides DP&L the option to request up to two one-year extensions of the maturity date. On June 6, 2019, DP&L closed on a $425.0 million issuance of First Mortgage Bonds due 2049. These new bonds carry an interest rate of 3.95% . The proceeds of this issuance were used to repay in full the outstanding principal of $435.0 million of DP&L's variable rate Term Loan B credit agreement. On March 30, 2018, DP&L commenced a redemption of $60.0 million of outstanding tax exempt First Mortgage Bonds due 2020 at par value (plus accrued and unpaid interest). These bonds were redeemed at par plus accrued interest on April 30, 2018 with cash on hand. Long-term debt covenants and restrictions DP&L’s Bond Purchase and Covenants Agreement (financing document entered into in connection with the sale of $200.0 million of variable rate tax-exempt First Mortgage Bonds, dated as of August 1, 2015) has two financial covenants. The first measures Total Debt to Total Capitalization and is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. DP&L’s Total Debt to Total Capitalization ratio shall not be greater than 0.65 to 1.00. Except that, after Generation Separation and the twelve-month period following (October 1, 2017 to September 30, 2018) the ratio shall be a) increased to 0.75 to 1.00 or b) suspended if DP&L’s long-term indebtedness is less than or equal to $750.0 million . Additionally, this covenant shall be suspended any time after separation during which DP&L maintains a rating of BBB- (or in the case of Moody’s Investors Service, Inc. Baa3) or higher with a stable outlook from at least one of Fitch Investors Service Inc., Standard & Poor’s Ratings Services or Moody’s Investors Service, Inc. The Total Debt to Capitalization covenant is calculated as the sum of DP&L’s current and long-term portion of debt, divided by the total of DP&L’s net worth and total debt. As of September 30, 2019 , DP&L's ratings meet those requirements and this covenant is suspended for the quarter ended September 30, 2019 . The second financial covenant measures EBITDA to Interest Expense. The Total EBITDA to Interest Charges ratio is calculated, at the end of each fiscal quarter, by dividing EBITDA for the four prior fiscal quarters by the interest charges for the same period. The ratio, per the agreement, is to be not less than 2.50 to 1.00. This financial covenant was met with a ratio of 9.36 to 1.00 as of September 30, 2019 . DP&L's unsecured revolving credit facility has one financial covenant. The covenant measures Total Debt to Total Capitalization and is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. DP&L’s Total Debt to Total Capitalization ratio shall not be greater than 0.67 to 1.00. This financial covenant was met with a ratio of 0.58 to 1.00 as of September 30, 2019 . As of September 30, 2019 , DP&L was in compliance with all debt covenants, including the financial covenants described above. DP&L does not have any meaningful restrictions in its debt financing documents prohibiting dividends to its parent, DPL. Substantially all property, plant & equipment of DP&L is subject to the lien of the mortgage securing DP&L’s First and Refunding Mortgage.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Income Taxes	Income Taxes The following table details the effective tax rates for the three and nine months ended September 30, 2019 and 2018 . Three months ended Nine months ended September 30, September 30, 2019 2018 2019 2018 DPL (35.6)% 16.3% (9.8)% 15.2% Income tax expense for the nine months ended September 30, 2019 and 2018 was calculated using the estimated annual effective income tax rates for 2019 and 2018 of (10.1)% and 16.8% , respectively. Management estimates the annual effective tax rate based on its forecast of annual pre-tax income. To the extent that actual pre-tax results for the year differ from the forecasts applied to the most recent interim period, the estimated rates could be materially different from the actual effective tax rates. DPL’s effective combined state and federal income tax rate for all operations was (35.6)% and (9.8)% for the three and nine months ended September 30, 2019 , respectively. These rates are lower than the combined federal and state statutory rate of 21.6% primarily due to the flowthrough of the net tax benefit related to the reversal of excess deferred taxes of DP&L and the impact of the September 26, 2019 PUCO order which finalized the amount of excess deferred tax balances allocable to DP&L’s utility customers . For the nine months ended September 30, 2019 , DPL’s current period effective tax rate for all operations was not materially different than the estimated annual effective rate. Per the terms of DP&L's 2017 ESP, DPL will not make any tax-sharing payments to AES and AES will forgo collection of the payments during the term of the DMR. As such, during the nine months ended September 30, 2019 and 2018, DPL converted $2.7 million and $30.2 million , respectively, of accrued tax sharing liabilities with AES to additional equity investment in DPL .
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Income Taxes	Income Taxes The following table details the effective tax rates for the three and nine months ended September 30, 2019 and 2018 . Three months ended Nine months ended September 30, September 30, 2019 2018 2019 2018 DP&L (19.1)% 16.8% 4.7% 16.2% Income tax expense for the nine months ended September 30, 2019 and 2018 was calculated using the estimated annual effective income tax rates for 2019 and 2018 of 4.5% and 17.1% , respectively. Management estimates the annual effective tax rate based on its forecast of annual pre-tax income. To the extent that actual pre-tax results for the year differ from the forecasts applied to the most recent interim period, the estimated rates could be materially different from the actual effective tax rates. DP&L’s effective combined state and federal income tax rate was (19.1)% and 4.7% for the three and nine months ended September 30, 2019 , respectively. This is lower than the combined federal and state statutory rate of 21.6% primarily due to the net tax benefit related to the reversal of excess deferred taxes and the impact of the September 26, 2019 PUCO order which finalized the amount of excess deferred tax balances allocable to DP&L’s utility customers . For the nine months ended September 30, 2019 , DP&L’s current period effective tax rate for all operations was not materially different than the estimated annual effective rate.

Benefit Plans

Benefit Plans	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Pension and Postretirement Benefits	Benefit Plans DP&L sponsors a defined benefit pension plan for the majority of its employees. We generally fund pension plan benefits as accrued in accordance with the minimum funding requirements of ERISA and, in addition, make voluntary contributions from time to time. There were $7.5 million in employer contributions during each of the nine months ended September 30, 2019 and 2018. The amounts presented in the following tables for pension include the collective bargaining plan formula, the traditional management plan formula, the cash balance plan formula and the SERP, in the aggregate. The pension costs below have not been adjusted for amounts billed to the Service Company for former DP&L employees who are now employed by the Service Company that are still participants in the DP&L plan. The net periodic benefit cost of the pension benefit plans for the three and nine months ended September 30, 2019 and 2018 was: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Service cost $ 0.9 $ 1.5 $ 2.7 $ 4.5 Interest cost 3.7 3.4 11.2 10.3 Expected return on plan assets (5.0 ) (5.3 ) (15.0 ) (15.9 ) Amortization of unrecognized: Prior service cost 0.3 0.3 0.9 0.8 Actuarial loss 1.1 1.6 3.2 4.8 Net periodic benefit cost $ 1.0 $ 1.5 $ 3.0 $ 4.5 In addition, DP&L provides postretirement health care and life insurance benefits to certain retired employees, their spouses and eligible dependents. We have funded a portion of the union-eligible benefits using a Voluntary Employee Beneficiary Association Trust. These postretirement health care benefits and the related unfunded obligation of $9.0 million at September 30, 2019 and $9.2 million at December 31, 2018 were not material to the financial statements in the periods covered by this report.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Pension and Postretirement Benefits	Benefit Plans DP&L sponsors a defined benefit pension plan for the majority of its employees. We generally fund pension plan benefits as accrued in accordance with the minimum funding requirements of ERISA and, in addition, make voluntary contributions from time to time. There were $7.5 million in employer contributions during each of the nine months ended September 30, 2019 and 2018. The amounts presented in the following tables for pension include the collective bargaining plan formula, the traditional management plan formula, the cash balance plan formula and the SERP, in the aggregate. The pension costs below have not been adjusted for amounts billed to the Service Company for former DP&L employees who are now employed by the Service Company or for amounts billed to AES Ohio Generation for employees employed by AES Ohio Generation that are still participants in the DP&L plan. The net periodic benefit cost of the pension benefit plans for the three and nine months ended September 30, 2019 and 2018 was: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Service cost $ 0.9 $ 1.5 $ 2.7 $ 4.5 Interest cost 3.7 3.4 11.2 10.3 Expected return on plan assets (5.0 ) (5.3 ) (15.0 ) (15.9 ) Amortization of unrecognized: Prior service cost 0.4 0.4 1.3 1.1 Actuarial loss 1.8 2.4 5.3 7.1 Net periodic benefit cost $ 1.8 $ 2.4 $ 5.5 $ 7.1 In addition, DP&L provides postretirement health care and life insurance benefits to certain retired employees, their spouses and eligible dependents. We have funded a portion of the union-eligible benefits using a Voluntary Employee Beneficiary Association Trust. These postretirement health care benefits and the related unfunded obligation of $9.0 million at September 30, 2019 and $9.2 million at December 31, 2018 were not material to the financial statements in the periods covered by this report.

Shareholder's Equity

Shareholder's Equity	9 Months Ended
	Sep. 30, 2019
Class of Stock [Line Items]
Shareholder's Equity	Shareholder's Defici t Capital Contributions from AES DP&L's approved six-year 2017 ESP restricts DPL from making dividend payments to its parent company, AES, during the term of the ESP, as well as from making tax-sharing payments to AES during the term of the DMR. The 2017 ESP also requires that existing tax payments owed by DPL to AES, and similar tax payments that accrue during the term of the DMR, be converted into equity investments in DPL . For the nine months ended September 30, 2019 and 2018 , AES made capital contributions of $2.7 million and $30.2 million , respectively, by converting the amount owed to it by DPL related to tax-sharing payments for current tax liabilities.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Shareholder's Equity	Shareholder's Equity Capital Contribution and Returns of Capital During the nine months ended September 30, 2019 , DP&L made returns of capital payments of $90.0 million to DPL . During the nine months ended September 30, 2018 , DP&L received an $80.0 million capital contribution from its parent, DPL. In addition, DP&L made returns of capital payments of $43.8 million to DPL .

Contractual Obligations, Commer

Contractual Obligations, Commercial Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Contractual Obligations, Commercial Commitments and Contingencies	Contractual Obligations, Commercial Commitments and Contingencies Guarantees In the normal course of business, DPL enters into various agreements with its wholly-owned subsidiary, AES Ohio Generation , providing financial or performance assurance to third parties. These agreements are entered into primarily to support or enhance the creditworthiness otherwise attributed to this subsidiary on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish this subsidiary's intended commercial purposes. At September 30, 2019 , DPL had $21.0 million of guarantees on behalf of AES Ohio Generation to third parties for future financial or performance assurance under such agreements. The guarantee arrangements entered into by DPL with these third parties cover select present and future obligations of AES Ohio Generation to such beneficiaries and are terminable by DPL upon written notice to the beneficiaries within a certain time. At September 30, 2019 and December 31, 2018 , we had no outstanding balance of obligations covered by these guarantees . To date, DPL has not incurred any losses related to the guarantees of AES Ohio Generation ’s obligations and we believe it is unlikely that DPL would be required to perform or incur any losses in the future associated with any of the above guarantees. Equity Ownership Interest DP&L has a 4.9% equity ownership interest in OVEC, which is recorded using the cost method of accounting under GAAP. DP&L , along with several non-affiliated energy companies party to an OVEC arrangement, receive and pay for OVEC capacity and energy and are responsible for OVEC debt obligations and other fixed costs in proportion to their power participation ratios under the arrangement which, for DP&L, is the same as its equity ownership interest. At September 30, 2019 , DP&L could be responsible for the repayment of 4.9% , or $67.2 million , of $1,371.3 million OVEC debt obligations if they came due, comprised of both fixed and variable rate securities with maturities from 2022 to 2040 . OVEC could also seek additional contributions from DP&L to avoid a default in the event that other OVEC members defaulted on their respective OVEC obligations. One of the other OVEC members, with a 4.85% interest in OVEC, filed for bankruptcy protection and the bankruptcy court approved that member's rejection of the OVEC arrangement and its related obligations on July 31, 2018. We do not expect these events to have a material impact on our financial condition, results of operations or cash flows. Contingencies In the normal course of business, we are subject to various lawsuits, actions, proceedings, claims and other matters asserted under various laws and regulations. We believe the amounts provided in our Condensed Consolidated Financial Statements, as prescribed by GAAP, are adequate considering the probable and estimable contingencies. However, there can be no assurances that the actual amounts required to satisfy alleged liabilities from various legal proceedings, claims, tax examinations and other matters discussed below, and to comply with applicable laws and regulations, will not exceed the amounts reflected in our Condensed Consolidated Financial Statements. As such, costs, if any, that may be incurred in excess of those amounts provided as of September 30, 2019 , cannot be reasonably determined. Environmental Matters DPL’s and DP&L’s facilities and operations are subject to a wide range of federal, state and local environmental regulations and laws. The environmental issues that may affect us include: • The federal CAA and state laws and regulations (including State Implementation Plans) which require compliance, obtaining permits and reporting as to air emissions; • Litigation with federal and certain state governments and certain special interest groups; • Rules and future rules issued by the USEPA, the Ohio EPA or other authorities associated with the federal Clean Water Act, which prohibits the discharge of pollutants into waters of the United States except pursuant to appropriate permits; and • Solid and hazardous waste laws and regulations, which govern the management and disposal of certain waste. The majority of solid waste created from the combustion of coal and fossil fuels consists of fly ash and other coal combustion by-products. In addition to imposing continuing compliance obligations, these laws and regulations authorize the imposition of substantial penalties for noncompliance, including fines, injunctive relief and other sanctions. In the normal course of business, we have investigatory and remedial activities underway at our facilities to comply, or to determine compliance, with such regulations. We record liabilities for loss contingencies related to environmental matters when a loss is probable of occurring and can be reasonably estimated in accordance with the provisions of GAAP. Accordingly, we have immaterial accruals for loss contingencies for environmental matters. We also have several environmental matters for which we have not accrued loss contingencies because the risk of loss is not probable, or a loss cannot be reasonably estimated. We evaluate the potential liability related to environmental matters quarterly and may revise our estimates. Such revisions in the estimates of the potential liabilities could have a material adverse effect on our results of operations, financial condition and cash flows. We have several pending environmental matters associated with our current and previously owned coal-fired generation units. Some of these matters could have a material adverse effect on our results of operations, financial condition and cash flows.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Contractual Obligations, Commercial Commitments and Contingencies	Contractual Obligations, Commercial Commitments and Contingencies Equity Ownership Interest DP&L has a 4.9% equity ownership interest in OVEC, which is recorded using the cost method of accounting under GAAP. DP&L , along with several non-affiliated energy companies party to an OVEC arrangement, receive and pay for OVEC capacity and energy and are responsible for OVEC debt obligations and other fixed costs in proportion to their power participation ratios under the arrangement which, for DP&L, is the same as its equity ownership interest. At September 30, 2019 , DP&L could be responsible for the repayment of 4.9% , or $67.2 million , of $1,371.3 million OVEC debt obligations if they came due, comprised of both fixed and variable rate securities with maturities from 2022 to 2040 . OVEC could also seek additional contributions from DP&L to avoid a default in the event that other OVEC members defaulted on their respective OVEC obligations. One of the other OVEC members, with a 4.85% interest in OVEC, filed for bankruptcy protection and the bankruptcy court approved that member's rejection of the OVEC arrangement and its related obligations on July 31, 2018. We do not expect these events to have a material impact on our financial condition, results of operations or cash flows. Contingencies In the normal course of business, we are subject to various lawsuits, actions, proceedings, claims and other matters asserted under various laws and regulations. We believe the amounts provided in our Condensed Financial Statements, as prescribed by GAAP, are adequate considering the probable and estimable contingencies. However, there can be no assurances that the actual amounts required to satisfy alleged liabilities from various legal proceedings, claims, tax examinations and other matters discussed below, and to comply with applicable laws and regulations, will not exceed the amounts reflected in our Condensed Financial Statements. As such, costs, if any, that may be incurred in excess of those amounts provided as of September 30, 2019 , cannot be reasonably determined. Environmental Matters DP&L’s facilities and operations are subject to a wide range of federal, state and local environmental regulations and laws. The environmental issues that may affect us include: • The federal CAA and state laws and regulations (including State Implementation Plans) which require compliance, obtaining permits and reporting as to air emissions; • Litigation with federal and certain state governments and certain special interest groups; • Rules and future rules issued by the USEPA, the Ohio EPA or other authorities associated with the federal Clean Water Act, which prohibits the discharge of pollutants into waters of the United States except pursuant to appropriate permits; and • Solid and hazardous waste laws and regulations, which govern the management and disposal of certain waste. In addition to imposing continuing compliance obligations, these laws and regulations authorize the imposition of substantial penalties for noncompliance, including fines, injunctive relief and other sanctions. In the normal course of business, we have investigatory and remedial activities underway at our facilities to comply, or to determine compliance, with such regulations. We record liabilities for loss contingencies related to environmental matters when a loss is probable of occurring and can be reasonably estimated in accordance with the provisions of GAAP. Accordingly, we have immaterial accruals for loss contingencies for environmental matters. We also have several environmental matters for which we have not accrued loss contingencies because the risk of loss is not probable, or a loss cannot be reasonably estimated. We evaluate the potential liability related to environmental matters quarterly and may revise our estimates. Such revisions in the estimates of the potential liabilities could have a material adverse effect on our results of operations, financial condition and cash flows.

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2019
Segment Reporting Information [Line Items]
Business Segments	Business Segments DPL has presented the results of operations of Miami Fort Station, Zimmer Station, the Peaker Assets, Stuart Station, and Killen Station as discontinued operations as a group of components for all periods presented. For more information, see Note 14 – Discontinued Operations of Notes to DPL's Condensed Consolidated Financial Statements . As such, AES Ohio Generation only has operating activity coming from its undivided ownership interest in Conesville, which does not meet the thresholds to be a separate reportable operating segment. Therefore, DPL manages its business through one reportable operating segment, the Utility segment. The primary segment performance measure is income / (loss) from continuing operations before income tax as management has concluded that this measure best reflects the underlying business performance of DPL and is the most relevant measure considered in DPL’s internal evaluation of the financial performance of its segment. The Utility segment is discussed further below. Utility Segment The Utility segment is comprised of DP&L’s electric transmission and distribution businesses, which distribute electricity to residential, commercial, industrial and governmental customers. DP&L distributes electricity to more than 524,000 retail customers located in a 6,000 -square mile area of West Central Ohio. DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses recording regulatory assets when incurred costs are expected to be recovered in future customer rates and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. The Utility segment includes revenues and costs associated with our investment in OVEC and the historical results of DP&L’s Beckjord Facility, which was closed in 2014 and transferred to a third party in the first quarter of 2018, and Hutchings Coal generating facility, which was closed in 2013. These assets did not transfer to AES Ohio Generation as part of DP&L's Generation Separation on October 1, 2017. Thus, they are grouped within the Utility segment for segment reporting purposes. In addition, regulatory deferrals and collections, which include fuel deferrals in historical periods, are included in the Utility segment. Included within the “Other” column are other businesses that do not meet the GAAP requirements for disclosure as reportable segments as well as certain corporate costs, which include interest expense and loss on early extinguishment of debt on DPL's long-term debt as well as adjustments related to purchase accounting from the Merger. DPL's undivided interest in Conesville is included within the "Other" column as it does not meet the requirement for disclosure as a reportable operating segment, since the results of operations of the other EGUs are presented as discontinued operations. The accounting policies of the reportable segment are the same as those described in Note 1 – Overview and Summary of Significant Accounting Policies of our 10-K. Intersegment sales, costs of sales and expenses are eliminated in consolidation. Certain shared and corporate costs are allocated between "Other" and the Utility reporting segment. The following tables present financial information for DPL’s Utility reportable business segment: $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Three months ended September 30, 2019 Revenues from external customers $ 190.9 $ 8.1 $ — $ 199.0 Intersegment revenues 0.2 0.8 (1.0 ) — Total revenues $ 191.1 $ 8.9 $ (1.0 ) $ 199.0 Depreciation and amortization $ 17.4 $ 0.3 $ — $ 17.7 Interest expense $ 6.1 $ 12.2 $ — $ 18.3 Income / (loss) from continuing operations before income tax $ 37.7 $ (11.2 ) $ — $ 26.5 Cash capital expenditures $ 58.9 $ 0.1 $ — $ 59.0 $ in millions Utility Other (a) Adjustments and Eliminations DPL Consolidated Three Months Ended September 30, 2018 Revenues from external customers $ 198.5 $ 9.2 $ — $ 207.7 Intersegment revenues 0.2 0.7 (0.9 ) — Total revenues $ 198.7 $ 9.9 $ (0.9 ) $ 207.7 Depreciation and amortization $ 19.1 $ 0.6 $ — $ 19.7 Interest expense $ 5.8 $ 16.8 $ — $ 22.6 Income / (loss) from continuing operations before income tax $ 37.5 $ (17.7 ) $ — $ 19.8 Cash capital expenditures $ 20.5 $ 4.6 $ — $ 25.1 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2019 Revenues from external customers $ 569.4 $ 22.8 $ — $ 592.2 Intersegment revenues 0.8 2.4 (3.2 ) — Total revenues $ 570.2 $ 25.2 $ (3.2 ) $ 592.2 Depreciation and amortization $ 52.9 $ 1.2 $ — $ 54.1 Interest expense $ 19.9 $ 43.8 $ — $ 63.7 Loss on early extinguishment of debt $ — $ 44.9 $ — $ 44.9 Income / (loss) from continuing operations before income tax $ 108.8 $ (85.8 ) $ — $ 23.0 Cash capital expenditures $ 121.1 $ 1.3 $ — $ 122.4 $ in millions Utility Other (a) Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2018 Revenues from external customers $ 562.9 $ 28.6 $ — $ 591.5 Intersegment revenues 0.6 2.1 (2.7 ) — Total revenues $ 563.5 $ 30.7 $ (2.7 ) $ 591.5 Depreciation and amortization $ 56.5 $ 2.3 $ — $ 58.8 Interest expense $ 20.5 $ 53.9 $ — $ 74.4 Income / (loss) from continuing operations before income tax $ 73.9 $ (60.2 ) $ — $ 13.7 Cash capital expenditures $ 65.0 $ 10.8 $ — $ 75.8 (a) "Other" includes Cash capital expenditures related to assets of discontinued operations and held-for-sale businesses for the three and nine months ended September 30, 2018. Total Assets September 30, 2019 December 31, 2018 Utility $ 1,779.4 $ 1,819.6 All Other (a) 36.9 63.5 DPL Consolidated $ 1,816.3 $ 1,883.1 (a) "All Other" includes Total assets related to the assets of discontinued operations and held-for-sale businesses and Eliminations for all periods presented.

Revenue (Notes)

Revenue (Notes)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Text Block]	Revenue Revenue is primarily earned from retail and wholesale electricity sales and electricity transmission and distribution delivery services. Revenue is recognized upon transfer of control to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. Revenue is recorded net of any taxes assessed on and collected from customers, which are remitted to the governmental authorities. For further discussion of our Retail, Wholesale, RTO ancillary, and Capacity revenues, see Note 14 — Revenue in Item 8.— Financial Statements and Supplementary Data of our Form 10-K. DPL's revenue from contracts with customers was $195.0 million and $195.1 million for the three months ended September 30, 2019 and 2018, respectively, and $576.5 million and $560.1 million for the nine months ended September 30, 2019 and 2018, respectively. The following table presents our revenue from contracts with customers and other revenue by segment for the three and nine months ended September 30, 2019 and 2018 : $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2019 Retail revenue Retail revenue from contracts with customers $ 170.5 $ — $ — $ 170.5 Other retail revenue (a) 3.8 — — 3.8 Wholesale revenue Wholesale revenue from contracts with customers 4.4 5.0 (0.2 ) 9.2 RTO ancillary revenue 11.0 0.1 — 11.1 Capacity revenue 1.1 1.1 — 2.2 Miscellaneous revenue from contracts with customers (b) — 2.0 — 2.0 Miscellaneous revenue 0.3 0.7 (0.8 ) 0.2 Total revenues $ 191.1 $ 8.9 $ (1.0 ) $ 199.0 Three Months Ended September 30, 2018 Retail revenue Retail revenue from contracts with customers $ 168.4 $ — $ (0.4 ) $ 168.0 Other retail revenue (a) 12.6 — — 12.6 Wholesale revenue Wholesale revenue from contracts with customers 4.9 5.6 — 10.5 RTO ancillary revenue 10.8 (0.1 ) — 10.7 Capacity revenue 2.0 1.7 — 3.7 Miscellaneous revenue from contracts with customers (b) — 2.2 — 2.2 Miscellaneous revenue — 0.5 (0.5 ) — Total revenues $ 198.7 $ 9.9 $ (0.9 ) $ 207.7 Nine months ended September 30, 2019 Retail revenue Retail revenue from contracts with customers $ 503.8 $ — $ — $ 503.8 Other retail revenue (a) 14.9 — — 14.9 Wholesale revenue Wholesale revenue from contracts with customers 12.8 11.4 (0.8 ) 23.4 RTO ancillary revenue 32.8 0.2 — 33.0 Capacity revenue 5.0 4.2 — 9.2 Miscellaneous revenue from contracts with customers (b) — 7.1 — 7.1 Miscellaneous revenue 0.9 2.3 (2.4 ) 0.8 Total revenues $ 570.2 $ 25.2 $ (3.2 ) $ 592.2 Nine months ended September 30, 2018 Retail revenue Retail revenue from contracts with customers $ 469.3 $ — $ (0.8 ) $ 468.5 Other retail revenue (a) 31.4 — — 31.4 Wholesale revenue Wholesale revenue from contracts with customers 24.6 16.7 — 41.3 RTO ancillary revenue 32.4 0.1 — 32.5 Capacity revenue 5.8 4.7 — 10.5 Miscellaneous revenue from contracts with customers (b) — 7.3 — 7.3 Miscellaneous revenue — 1.9 (1.9 ) — Total revenues $ 563.5 $ 30.7 $ (2.7 ) $ 591.5 (a) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. (b) Miscellaneous revenue from contracts with customers primarily includes revenues for various services provided by Miami Valley Lighting. The balances of receivables from contracts with customers were $66.3 million and $72.6 million as of September 30, 2019 and December 31, 2018 , respectively. Payment terms for all receivables from contracts with customers are typically within 30 days.
Subsidiaries [Member]
Revenue from Contract with Customer [Text Block]	Revenue Revenue is primarily earned from retail and wholesale electricity sales and electricity transmission and distribution delivery services. Revenue is recognized upon transfer of control to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. Revenue is recorded net of any taxes assessed on and collected from customers, which are remitted to the governmental authorities. For further discussion of our Retail, Wholesale, RTO ancillary, and Capacity revenues, see Note 13 — Revenue in Item 8.— Financial Statements and Supplementary Data of our Form 10-K. DP&L's revenue from contracts with customers was $187.0 million and $186.1 million for the three months ended September 30, 2019 and 2018, respectively, and $554.4 million and $532.1 million for the nine months ended September 30, 2019 and 2018, respectively. The following table presents our revenue from contracts with customers and other revenue for the three and nine months ended September 30, 2019 and 2018 : Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Retail revenue Retail revenue from contracts with customers $ 170.5 $ 168.4 $ 503.8 $ 469.3 Other retail revenue (a) 3.8 12.6 14.9 31.4 Wholesale revenue Wholesale revenue from contracts with customers 4.4 4.9 12.8 24.6 RTO ancillary revenue 11.0 10.8 32.8 32.4 Capacity revenue 1.1 2.0 5.0 5.8 Miscellaneous revenue 0.3 — 0.9 — Total revenues $ 191.1 $ 198.7 $ 570.2 $ 563.5 (a) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. The balances of receivables from contracts with customers were $65.2 million and $70.1 million as of September 30, 2019 and December 31, 2018 , respectively. Payment terms for all receivables from contracts with customers are typically within 30 days.

Dispositions (Notes)

Dispositions (Notes)	9 Months Ended
	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Dispositions Beckjord Facility – On February 26, 2018, DP&L and its co-owners of the retired Beckjord Facility agreed to transfer their interests in the retired Facility to a third party, including their obligations to remediate the Facility and its site, and the transfer occurred on that same date. As a result, DPL recognized a loss on the transfer of $11.7 million and made cash expenditures of $14.5 million , inclusive of cash expenditures for the transfer charges. The Beckjord Facility was retired in 2014, and, as such, the income / (loss) from continuing operations before income tax related to the Beckjord Facility was immaterial for the three and nine months ended September 30, 2018 , excluding the loss on transfer noted above. Prior to the transfer, the Beckjord Facility was included in the Utility segment. Discontinued Operations On December 8, 2017, DPL and AES Ohio Generation completed the sale of their entire undivided interest in the Miami Fort Station and the Zimmer Station. On March 27, 2018, DPL and AES Ohio Generation completed the sale of the Peaker assets to Kimura Power, LLC, and this transaction resulted in a loss on sale of $1.9 million for the nine months ended September 30, 2018 . Further, on May 31, 2018, DPL and AES Ohio Generation retired the Stuart Station coal-fired and diesel-fired generating units and the Killen Station coal-fired generating unit and combustion turbine as planned. Consequently, we determined that the disposal of this group of components, as a whole, represents a strategic shift to exit generation, and, as such, qualifies to be presented as discontinued operations. Therefore, the results of operations, assets and liabilities of this group of components were reported as such in the Condensed Consolidated Statements of Operations and Condensed Consolidated Balance Sheets for all periods presented. The following table summarizes the major categories of assets and liabilities at the dates indicated: $ in millions September 30, 2019 December 31, 2018 Accounts receivable, net $ 6.8 $ 4.0 Taxes applicable to subsequent years 0.6 2.3 Prepayments and other current assets 0.9 2.4 Intangible assets, net of amortization 0.2 5.3 Total assets of the disposal group classified as assets of discontinued operations and held-for-sale businesses in the balance sheets $ 8.5 $ 14.0 Accounts payable $ 4.3 $ 3.9 Accrued taxes 2.4 3.1 Accrued and other current liabilities 3.2 5.2 Deferred income taxes (a) (33.2 ) (39.8 ) Taxes payable — 2.3 Accrued pension and other post-retirement benefits — 9.7 Asset retirement obligations 70.4 90.4 Other non-current liabilities 15.2 6.6 Total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets $ 62.3 $ 81.4 (a) Deferred income taxes represent the tax asset position of the discontinued group of components, which were netted with liabilities on DPL prior to classification as discontinued operations. The following table summarizes the revenues, operating costs, other expenses and income tax of discontinued operations for the periods indicated: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Revenues $ 10.1 $ 15.6 $ 41.0 $ 141.8 Operating costs and other expenses (10.5 ) (10.6 ) (8.2 ) (105.1 ) Income from discontinued operations (0.4 ) 5.0 32.8 36.7 Gain / (loss) from disposal of discontinued operations — 0.3 0.1 (1.6 ) Income tax expense from discontinued operations 0.1 1.0 7.1 5.9 Net income from discontinued operations $ (0.5 ) $ 4.3 $ 25.8 $ 29.2 Cash flows related to discontinued operations are included in our Condensed Consolidated Statements of Cash Flows. Cash flows from operating activities for discontinued operations were $(0.5) million and $(7.2) million for the three months ended September 30, 2019 and 2018 , respectively, and $12.4 million and $37.2 million for the nine months ended September 30, 2019 and 2018 , respectively. Cash flows from investing activities for discontinued operations were $233.8 million for the nine months ended September 30, 2018 . There were no cash flows from investing activities for the three and nine months ended September 30, 2019 or for the three months ended September 30, 2018. AROs of Discontinued Operations DPL's retired Stuart and Killen generating facilities continue to carry ARO liabilities consisting primarily of river intake and discharge structures, coal unloading facilities, landfills and ash disposal facilities. In the first quarter of 2019, DPL reduced the ARO liability related to the Stuart and Killen ash ponds and landfills by a combined $22.5 million based on updated internal analyses that reduced estimated closure costs associated with these ash ponds and landfills. The remaining ARO liability related to Stuart and Killen is included in the Asset retirement obligations balance in the total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets as of September 30, 2019 above. As these plants are no longer in service, the reduction to the ARO liability was also recorded as a credit to depreciation and amortization expense in the same amount. The credit to depreciation and amortization expense is included in operating costs and other expenses of discontinued operations for the nine months ended September 30, 2019 in the table above.
Subsidiaries [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Dispositions Beckjord Facility – On February 26, 2018, DP&L and its co-owners of the retired Beckjord Facility agreed to transfer their interests in the retired Facility to a third party, including their obligations to remediate the Facility and its site, and the transfer occurred on that same date. As a result, DP&L recognized a loss on the transfer of $12.4 million and made cash expenditures of $14.5 million , inclusive of cash expenditures for the transfer charges. The Beckjord Facility was retired in 2014, and, as such, the income / (loss) from continuing operations before income tax related to the Beckjord Facility was immaterial for the three and nine months ended September 30, 2018 , excluding the loss on transfer noted above.

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Dispositions Beckjord Facility – On February 26, 2018, DP&L and its co-owners of the retired Beckjord Facility agreed to transfer their interests in the retired Facility to a third party, including their obligations to remediate the Facility and its site, and the transfer occurred on that same date. As a result, DPL recognized a loss on the transfer of $11.7 million and made cash expenditures of $14.5 million , inclusive of cash expenditures for the transfer charges. The Beckjord Facility was retired in 2014, and, as such, the income / (loss) from continuing operations before income tax related to the Beckjord Facility was immaterial for the three and nine months ended September 30, 2018 , excluding the loss on transfer noted above. Prior to the transfer, the Beckjord Facility was included in the Utility segment. Discontinued Operations On December 8, 2017, DPL and AES Ohio Generation completed the sale of their entire undivided interest in the Miami Fort Station and the Zimmer Station. On March 27, 2018, DPL and AES Ohio Generation completed the sale of the Peaker assets to Kimura Power, LLC, and this transaction resulted in a loss on sale of $1.9 million for the nine months ended September 30, 2018 . Further, on May 31, 2018, DPL and AES Ohio Generation retired the Stuart Station coal-fired and diesel-fired generating units and the Killen Station coal-fired generating unit and combustion turbine as planned. Consequently, we determined that the disposal of this group of components, as a whole, represents a strategic shift to exit generation, and, as such, qualifies to be presented as discontinued operations. Therefore, the results of operations, assets and liabilities of this group of components were reported as such in the Condensed Consolidated Statements of Operations and Condensed Consolidated Balance Sheets for all periods presented. The following table summarizes the major categories of assets and liabilities at the dates indicated: $ in millions September 30, 2019 December 31, 2018 Accounts receivable, net $ 6.8 $ 4.0 Taxes applicable to subsequent years 0.6 2.3 Prepayments and other current assets 0.9 2.4 Intangible assets, net of amortization 0.2 5.3 Total assets of the disposal group classified as assets of discontinued operations and held-for-sale businesses in the balance sheets $ 8.5 $ 14.0 Accounts payable $ 4.3 $ 3.9 Accrued taxes 2.4 3.1 Accrued and other current liabilities 3.2 5.2 Deferred income taxes (a) (33.2 ) (39.8 ) Taxes payable — 2.3 Accrued pension and other post-retirement benefits — 9.7 Asset retirement obligations 70.4 90.4 Other non-current liabilities 15.2 6.6 Total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets $ 62.3 $ 81.4 (a) Deferred income taxes represent the tax asset position of the discontinued group of components, which were netted with liabilities on DPL prior to classification as discontinued operations. The following table summarizes the revenues, operating costs, other expenses and income tax of discontinued operations for the periods indicated: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Revenues $ 10.1 $ 15.6 $ 41.0 $ 141.8 Operating costs and other expenses (10.5 ) (10.6 ) (8.2 ) (105.1 ) Income from discontinued operations (0.4 ) 5.0 32.8 36.7 Gain / (loss) from disposal of discontinued operations — 0.3 0.1 (1.6 ) Income tax expense from discontinued operations 0.1 1.0 7.1 5.9 Net income from discontinued operations $ (0.5 ) $ 4.3 $ 25.8 $ 29.2 Cash flows related to discontinued operations are included in our Condensed Consolidated Statements of Cash Flows. Cash flows from operating activities for discontinued operations were $(0.5) million and $(7.2) million for the three months ended September 30, 2019 and 2018 , respectively, and $12.4 million and $37.2 million for the nine months ended September 30, 2019 and 2018 , respectively. Cash flows from investing activities for discontinued operations were $233.8 million for the nine months ended September 30, 2018 . There were no cash flows from investing activities for the three and nine months ended September 30, 2019 or for the three months ended September 30, 2018. AROs of Discontinued Operations DPL's retired Stuart and Killen generating facilities continue to carry ARO liabilities consisting primarily of river intake and discharge structures, coal unloading facilities, landfills and ash disposal facilities. In the first quarter of 2019, DPL reduced the ARO liability related to the Stuart and Killen ash ponds and landfills by a combined $22.5 million based on updated internal analyses that reduced estimated closure costs associated with these ash ponds and landfills. The remaining ARO liability related to Stuart and Killen is included in the Asset retirement obligations balance in the total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets as of September 30, 2019 above. As these plants are no longer in service, the reduction to the ARO liability was also recorded as a credit to depreciation and amortization expense in the same amount. The credit to depreciation and amortization expense is included in operating costs and other expenses of discontinued operations for the nine months ended September 30, 2019 in the table above.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2019
Significant Accounting Policies [Line Items]
Description of Business	Description of Business DPL is a regional energy company organized in 1985 under the laws of Ohio. DPL has one reportable segment: the Utility segment. See Note 11 – Business Segments for more information relating to this reportable segment. The terms “we,” “us,” “our” and “ours” are used to refer to DPL and its subsidiaries. DPL is an indirectly wholly-owned subsidiary of AES. DP&L , a wholly-owned subsidiary of DPL , is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service; however, retail transmission and distribution services are still regulated. DP&L has the exclusive right to provide such transmission and distribution services to approximately 524,000 customers located in West Central Ohio. Additionally, DP&L provides retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 - square mile area of West Central Ohio. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. Following the issuance of the DRO in September 2018 and the resulting changes to the decoupling rider effective January 1, 2019, DP&L's distribution sales are primarily impacted by customer growth within our service territory. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DPL’s other primary subsidiaries include MVIC and AES Ohio Generation. MVIC is our captive insurance company that provides insurance services to DPL and our other subsidiaries. AES Ohio Generation's only operating asset is an undivided interest in Conesville. AES Ohio Generation sells all of its energy and capacity into the wholesale market. DPL's subsidiaries are all wholly-owned. DPL also has a wholly-owned business trust, DPL Capital Trust II, formed for the purpose of issuing trust capital securities to investors. DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DPL and its subsidiaries employed 653 people as of September 30, 2019 , of which 642 were employed by DP&L. Approximately 57% of all DPL employees are under a collective bargaining agreement, which expires October 31, 2020 .
Financial Statement Presentation	Financial Statement Presentation DPL’s Condensed Consolidated Financial Statements include the accounts of DPL and its wholly-owned subsidiaries except for DPL Capital Trust II, which is not consolidated, consistent with the provisions of GAAP. As of September 30, 2019 , AES Ohio Generation has an undivided ownership interest in one coal-fired generating facility, which is included in the financial statements at a carrying value of zero as it has been fully impaired. Operating revenues and expenses of this facility are included on a pro rata basis in the corresponding lines in the Condensed Consolidated Statements of Operations. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. All material intercompany accounts and transactions are eliminated in consolidation. We have evaluated subsequent events through the date this report is issued. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2018 . In the opinion of our management, the Condensed Consolidated Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of September 30, 2019 ; our results of operations for the three and nine months ended September 30, 2019 and 2018 , our cash flows for the nine months ended September 30, 2019 and 2018 and the changes in our equity for the three and nine months ended September 30, 2019 and 2018 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, interim results for the three and nine months ended September 30, 2019 may not be indicative of our results that will be realized for the full year ending December 31, 2019 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: recognition of revenue including unbilled revenues, the carrying value of property, plant and equipment; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; and assets and liabilities related to employee benefits.
Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities	DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended September 30, 2019 and 2018 were $13.0 million and $13.8 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2019 and 2018 were $37.3 million and $39.2 million, respectively.
Recently Issued Accounting Standards	New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed consolidated financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Consolidated Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed consolidated financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $70.2 million in gross trade accounts receivable.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Description of Business	Description of Business DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service; however, retail transmission and distribution services are still regulated. DP&L has the exclusive right to provide such transmission and distribution services to approximately 524,000 customers located in West Central Ohio. Additionally, DP&L provides retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 - square mile area of West Central Ohio. As a result of Generation Separation, DP&L now only has one reportable segment, the Utility segment. In addition to DP&L's electric transmission and distribution businesses, the Utility segment includes revenues and costs associated with DP&L's investment in OVEC and the historical results of DP&L’s Beckjord and Hutchings Coal generating facilities, which have either been closed or sold. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. Following the issuance of the DRO in September 2018 and the resulting changes to the decoupling rider effective January 1, 2019, DP&L's distribution sales are primarily impacted by customer growth within our service territory. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DP&L is a subsidiary of DPL. The terms “we,” “us,” “our” and “ours” are used to refer to DP&L . DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DP&L employed 642 people as of September 30, 2019 . Approximately 58% of DP&L employees are under a collective bargaining agreement, which expires October 31, 2020 .
Financial Statement Presentation	Financial Statement Presentation DP&L does not have any subsidiaries. We have evaluated subsequent events through the date this report is issued. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2018 . In the opinion of our management, the Condensed Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of September 30, 2019 ; our results of operations for the three and nine months ended September 30, 2019 and 2018 , our cash flows for the nine months ended September 30, 2019 and 2018 and the changes in our equity for the three and nine months ended September 30, 2019 and 2018 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, interim results for the three and nine months ended September 30, 2019 may not be indicative of our results that will be realized for the full year ending December 31, 2019 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: recognition of revenue including unbilled revenues, the carrying value of property, plant and equipment; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; and assets and liabilities related to employee benefits.
Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities	DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended September 30, 2019 and 2018 were $13.0 million and $13.8 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2019 and 2018 were $37.3 million and $39.2 million, respectively.
Recently Issued Accounting Standards	New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $72.1 million in gross trade accounts receivable.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Related Party Transaction [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed consolidated financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Consolidated Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed consolidated financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $70.2 million in gross trade accounts receivable.
Schedule of Cash and Cash Equivalents [Table Text Block]	The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Consolidated Balance Sheet that reconcile to the total of such amounts as shown on the Condensed Consolidated Statements of Cash Flows: $ in millions September 30, 2019 December 31, 2018 Cash and cash equivalents $ 36.8 $ 90.5 Restricted cash 17.6 21.2 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 54.4 $ 111.7
Schedule of New Accounting Pronouncements	– The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed consolidated financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Consolidated Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our consolidated financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our consolidated financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed consolidated financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $70.2 million in gross trade accounts receivable.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Related Party Transaction [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	New accounting pronouncements adopted in 2019 – The following table provides a brief description of recently adopted accounting pronouncements that had an impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or did not have a material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from AOCI This amendment allows a reclassification of the stranded tax effects resulting from the implementation of the Tax Cuts and Jobs Act from AOCI to retained earnings at the election of the filer. Because this amendment only relates to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. January 1, 2019 We have not elected to reclassify any amounts to retained earnings. Our accounting policy for releasing the income tax effects from AOCI occurs on a portfolio basis. 2017-12, Derivatives and Hedging (Topic 815): Targeted improvements to Accounting for Hedging Activities The standard updates the hedge accounting model to expand the ability to hedge nonfinancial and financial risk components, reduce complexity, and ease certain documentation and assessment requirements. When facts and circumstances are the same as at the previous quantitative test, a subsequent quantitative effectiveness test is not required. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness. For cash flow hedges, this means that the entire change in the fair value of a hedging instrument will be recorded in other comprehensive income and amounts deferred will be reclassified to earnings in the same income statement line as the hedged item. January 1, 2019 The adoption of this standard had no material impact on our condensed financial statements. 2016-02, 2018-01, 2018-10, 2018-11 Leases (Topic 842) See " Adoption of FASC Topic 842, Leases " below. January 1, 2019 See impact upon adoption of the standard below. Adoption of FASC Topic 842, "Leases" On January 1, 2019, we adopted ASU 2016-02 Leases and its subsequent corresponding updates (“FASC 842”). Under this standard, lessees are required to recognize assets and liabilities for most leases and recognize expenses in a manner similar to the current accounting method. For lessors, the guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. The guidance eliminates current real estate-specific provisions. Under FASC 842, it is expected that fewer contracts will contain a lease. However, due to the elimination of the real estate-specific guidance and changes to certain lessor classification criteria, more leases will qualify as sales-type leases and direct financing leases. Under these two models, a lessor will derecognize the asset and will recognize a net investment in a lease. According to FASC 842, the net investment in the lease includes the fair value of the plant after the contract period but does not include variable payments such as margin on the sale of energy. Therefore, the net investment in the lease could be significantly different than the carrying amount of the underlying asset at lease commencement. In such circumstances, the difference between the initially recognized net investment in the lease and the carrying amount of the underlying asset is recognized as a gain/loss at lease commencement. During the course of adopting FASC 842, we applied various practical expedients including: • The package of practical expedients (applied to all leases) that allowed lessees and lessors not to reassess: a. whether any expired or existing contracts are or contain leases, b. lease classification for any expired or existing leases, and c. whether initial direct costs for any expired or existing leases qualify for capitalization under FASC 842. • The transition practical expedient related to land easements, allowing us to carry forward our accounting treatment for land easements on existing agreements, and • The transition practical expedient for lessees that allowed businesses to not separate lease and non-lease components. We applied the practical expedient to all classes of underlying assets when valuing right-of-use assets and lease liabilities. Contracts where we are the lessor were separated between the lease and non-lease components. We applied the modified retrospective method of adoption and elected to continue to apply the guidance in FASC 840 Leases to the comparative periods presented in the year of adoption. Under this transition method, we applied the transition provisions starting at the date of adoption. The adoption of FASC 842 did not have a material impact on our Condensed Financial Statements. New Accounting Pronouncements Issued But Not Yet Effective – The following table provides a brief description of recent accounting pronouncements that could have a material impact on our financial statements. Accounting pronouncements not listed below were assessed and determined to be either not applicable or are expected to have no material impact on our financial statements. ASU Number and Name Description Date of Adoption Effect on the financial statements upon adoption 2016-13, 2019-04, 2019-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 We will adopt the standard on January 1, 2020; see below for the evaluation of the impact of the adoption on the condensed financial statements. ASU 2016-13 and its subsequent corresponding updates will update the impairment model for financial assets measured at amortized cost. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowance for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses as it is done today, except that the losses will be recognized as an allowance rather than a reduction in the amortized cost of the securities. There are various transition methods available upon adoption. We are currently evaluating the impact of adopting the standard on our condensed financial statements; however, it is expected that the new current expected credit loss model will primarily impact the calculation of expected credit losses on $72.1 million in gross trade accounts receivable.
Schedule of Cash and Cash Equivalents [Table Text Block]	The following table provides a summary of cash, cash equivalents, and restricted cash amounts reported on the Condensed Balance Sheet that reconcile to the total of such amounts as shown on the Condensed Statements of Cash Flows: $ in millions September 30, 2019 December 31, 2018 Cash and cash equivalents $ 14.4 $ 45.0 Restricted cash 17.6 21.2 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 32.0 $ 66.2

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	9 Months Ended
	Sep. 30, 2019
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable and Inventories are as follows at September 30, 2019 and December 31, 2018 : September 30, December 31, $ in millions 2019 2018 Accounts receivable, net: Customer receivables $ 51.1 $ 55.8 Unbilled revenue 15.2 16.8 Amounts due from affiliates 0.2 — Due from PJM transmission enhancement settlement 2.4 16.5 Other 1.3 2.3 Provision for uncollectible accounts (0.4 ) (0.9 ) Total accounts receivable, net $ 69.8 $ 90.5 Inventories, at average cost: Fuel and limestone $ 3.0 $ 1.9 Materials and supplies 10.0 8.3 Other — 0.5 Total inventories, at average cost $ 13.0 $ 10.7
Reclassification out of Accumulated Other Comprehensive Income	The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and nine months ended September 30, 2019 and 2018 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Gains and losses on cash flow hedges (Note 5): Interest expense $ (0.3 ) $ (0.3 ) $ (0.9 ) $ (0.9 ) Income tax benefit / (expense) (0.1 ) 0.1 — 0.3 Net of income taxes (0.4 ) (0.2 ) (0.9 ) (0.6 ) Loss from discontinued operations — — — 4.3 Income tax benefit from discontinued operations (0.4 ) — (0.4 ) (1.5 ) Net of income taxes (0.4 ) — (0.4 ) 2.8 Amortization of defined benefit pension items (Note 8): Other expense 0.1 0.2 0.2 0.5 Income tax benefit (0.1 ) (0.1 ) (0.1 ) (0.1 ) Net of income taxes — 0.1 0.1 0.4 Total reclassifications for the period, net of income taxes $ (0.8 ) $ (0.1 ) $ (1.2 ) $ 2.6
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the nine months ended September 30, 2019 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligation Total Balance at January 1, 2019 $ 17.0 $ (14.8 ) $ 2.2 Other comprehensive loss before reclassifications (1.0 ) — (1.0 ) Amounts reclassified from AOCI to earnings (1.3 ) 0.1 (1.2 ) Net current period other comprehensive income / (loss) (2.3 ) 0.1 (2.2 ) Balance at September 30, 2019 $ 14.7 $ (14.7 ) $ —
Schedule of Other Operating Cost and Expense, by Component [Table Text Block]	The components of Operating expenses - other are summarized as follows: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Loss on disposal and sale of businesses $ — $ — $ — $ 11.7 Fixed-asset impairment — 1.6 — 2.8 Other — — 0.9 0.1 Net other expense / (income) $ — $ 1.6 $ 0.9 $ 14.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable and Inventories are as follows at September 30, 2019 and December 31, 2018 : September 30, December 31, $ in millions 2019 2018 Accounts receivable, net: Customer receivables $ 50.0 $ 53.3 Unbilled revenue 15.2 16.8 Amounts due from affiliates 3.2 2.3 Due from PJM transmission enhancement settlement 2.4 16.5 Other 1.3 2.4 Provision for uncollectible accounts (0.4 ) (0.9 ) Total accounts receivable, net $ 71.7 $ 90.4 Inventories, at average cost: Materials and supplies $ 9.8 $ 7.1 Other — 0.6 Total inventories, at average cost $ 9.8 $ 7.7
Reclassification out of Accumulated Other Comprehensive Income	The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and nine months ended September 30, 2019 and 2018 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Gains and losses on cash flow hedges (Note 5): Interest expense $ — $ (0.3 ) $ (0.1 ) $ (1.1 ) Income tax expense — 0.1 — 0.6 Net of income taxes — (0.2 ) (0.1 ) (0.5 ) Amortization of defined benefit pension items (Note 8): Other expense 0.8 1.0 2.6 3.2 Income tax expense / (benefit) 0.9 (0.2 ) (0.5 ) (0.7 ) Net of income taxes 1.7 0.8 2.1 2.5 Total reclassifications for the period, net of income taxes $ 1.7 $ 0.6 $ 2.0 $ 2.0
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the nine months ended September 30, 2019 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligation Total Balance at January 1, 2019 $ 0.6 $ (35.9 ) $ (35.3 ) Other comprehensive loss before reclassifications (0.9 ) — (0.9 ) Amounts reclassified from AOCI to earnings (0.1 ) 2.1 2.0 Net current period other comprehensive income / (loss) (1.0 ) 2.1 1.1 Balance at September 30, 2019 $ (0.4 ) $ (33.8 ) $ (34.2 )

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Cost Of Non-Derivative Instruments	The following table presents the fair value, carrying value and cost of our non-derivative instruments at September 30, 2019 and December 31, 2018 . Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities . September 30, 2019 December 31, 2018 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.4 $ 0.4 Equity securities 2.3 3.9 2.4 3.5 Debt securities 4.1 4.1 4.1 4.0 Hedge funds 0.1 0.1 0.1 0.1 Tangible assets 0.1 0.1 0.1 0.1 Total Assets $ 6.8 $ 8.4 $ 7.1 $ 8.1 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 1,362.9 $ 1,451.3 $ 1,475.9 $ 1,519.6
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at September 30, 2019 and December 31, 2018 and the respective category within the fair value hierarchy for DPL is as follows: $ in millions Fair value at September 30, 2019 (a) Fair value at December 31, 2018 (a) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Master Trust assets Money market funds $ 0.2 $ — $ — $ 0.2 $ 0.4 $ — $ — $ 0.4 Equity securities — 3.9 — 3.9 — 3.5 — 3.5 Debt securities — 4.1 — 4.1 — 4.0 — 4.0 Hedge funds — 0.1 — 0.1 — 0.1 — 0.1 Tangible assets — 0.1 — 0.1 — 0.1 — 0.1 Total Master Trust assets 0.2 8.2 — 8.4 0.4 7.7 — 8.1 Derivative assets Interest rate hedges — 0.2 — 0.2 — 1.5 — 1.5 Total Derivative assets — 0.2 — 0.2 — 1.5 — 1.5 Total Assets $ 0.2 $ 8.4 $ — $ 8.6 $ 0.4 $ 9.2 $ — $ 9.6 Liabilities Long-term debt $ — $ 1,433.7 $ 17.6 $ 1,451.3 $ — $ 1,501.9 $ 17.7 $ 1,519.6 Total Liabilities $ — $ 1,433.7 $ 17.6 $ 1,451.3 $ — $ 1,501.9 $ 17.7 $ 1,519.6 (a) Includes credit valuation adjustment
THE DAYTON POWER AND LIGHT COMPANY [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Cost Of Non-Derivative Instruments	The following table presents the fair value, carrying value and cost of our non-derivative instruments at September 30, 2019 and December 31, 2018 . Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities . September 30, 2019 December 31, 2018 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.4 $ 0.4 Equity securities 2.3 3.9 2.4 3.5 Debt securities 4.1 4.1 4.1 4.0 Hedge funds 0.1 0.1 0.1 0.1 Tangible assets 0.1 0.1 0.1 0.1 Total assets $ 6.8 $ 8.4 $ 7.1 $ 8.1 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 574.2 $ 631.0 $ 586.1 $ 593.8
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at September 30, 2019 and December 31, 2018 and the respective category within the fair value hierarchy for DP&L is as follows: $ in millions Fair value at September 30, 2019 (a) Fair value at December 31, 2018 (a) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Master Trust assets Money market funds $ 0.2 $ — $ — $ 0.2 $ 0.4 $ — $ — $ 0.4 Equity securities — 3.9 — 3.9 — 3.5 — 3.5 Debt securities — 4.1 — 4.1 — 4.0 — 4.0 Hedge funds — 0.1 — 0.1 — 0.1 — 0.1 Tangible assets — 0.1 — 0.1 — 0.1 — 0.1 Total Master Trust assets 0.2 8.2 — 8.4 0.4 7.7 — 8.1 Derivative assets Interest rate hedges — 0.2 — 0.2 — 1.5 — 1.5 Total derivative assets — 0.2 — 0.2 — 1.5 — 1.5 Total assets $ 0.2 $ 8.4 $ — $ 8.6 $ 0.4 $ 9.2 $ — $ 9.6 Liabilities Long-term debt $ — $ 613.4 $ 17.6 631.0 $ — $ 576.1 $ 17.7 $ 593.8 Total liabilities $ — $ 613.4 $ 17.6 $ 631.0 $ — $ 576.1 $ 17.7 $ 593.8 (a) Includes credit valuation adjustment

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains or Losses Recognized in AOCI for the Cash Flow Hedges	The following tables provide information concerning gains or losses recognized in AOCI for the cash flow hedges for the three and nine months ended September 30, 2019 and 2018 : Three months ended Three months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gains in AOCI $ 0.4 $ 15.3 $ — $ 17.4 Net gains / (losses) associated with current period hedging transactions — (0.2 ) — 0.1 Net gains reclassified to earnings Interest expense — (0.4 ) — (0.2 ) (Income) / loss from discontinued operations (0.4 ) — — — Ending accumulated derivative gains in AOCI $ — $ 14.7 $ — $ 17.3 Nine months ended Nine months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gains / (losses) in AOCI $ 0.4 $ 16.6 $ (2.8 ) $ 17.5 Net gains / (losses) associated with current period hedging transactions — (1.0 ) — 0.4 Net (gains) / losses reclassified to earnings Interest expense — (0.9 ) — (0.6 ) (Income) / loss from discontinued operations (0.4 ) — 2.8 — Ending accumulated derivative gains in AOCI $ — $ 14.7 $ — $ 17.3 Portion expected to be reclassified to earnings in the next twelve months $ (1.2 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 11 Net gains or losses associated with the ineffective portion of the hedging transactions were immaterial in the prior year period presented.
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	DPL has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The fair value derivative position of DPL's interest rate swaps are as follows: Fair Values of Derivative Instruments at September 30, 2019 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swap Designated $ 0.2 $ — $ — $ 0.2 Total assets $ 0.2 $ — $ — $ 0.2 (a) Includes credit valuation adjustment. Fair Values of Derivative Instruments at December 31, 2018 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swaps Designated $ 0.9 $ — $ — $ 0.9 Long-term derivative positions (presented in Other non-current assets) Interest rate swaps Designated 0.6 — — 0.6 Total assets $ 1.5 $ — $ — $ 1.5 (a) Includes credit valuation adjustment.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains or Losses Recognized in AOCI for the Cash Flow Hedges	The following tables provide information concerning gains or losses recognized in AOCI for the cash flow hedges for the three and nine months ended September 30, 2019 and 2018 : Three months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains / (losses) in AOCI $ (0.3 ) $ 1.6 Net losses associated with current period hedging transactions (0.1 ) — Net gains reclassified to earnings Interest expense — (0.2 ) Ending accumulated derivative gains / (losses) in AOCI $ (0.4 ) $ 1.4 Nine months ended September 30, 2019 September 30, 2018 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains in AOCI $ 0.6 $ 1.4 Net gains / (losses) associated with current period hedging transactions (0.9 ) 0.5 Net gains reclassified to earnings Interest expense (0.1 ) (0.5 ) Ending accumulated derivative gains / (losses) in AOCI $ (0.4 ) $ 1.4 Portion expected to be reclassified to earnings in the next twelve months $ (0.2 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 11
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	DP&L has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The fair value derivative position of DP&L's interest rate swaps are as follows: Fair Values of Derivative Instruments at September 30, 2019 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swap Designated $ 0.2 $ — $ — $ 0.2 Total assets $ 0.2 $ — $ — $ 0.2 (a) Includes credit valuation adjustment. Fair Values of Derivative Instruments at December 31, 2018 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets (a) Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Fair Value Assets Short-term derivative positions (presented in Prepayments and other current assets) Interest rate swaps Designated $ 0.9 $ — $ — $ 0.9 Long-term derivative positions (presented in Other non-current assets) Interest rate swaps Designated 0.6 — — 0.6 Total assets $ 1.5 $ — $ — $ 1.5 (a) Includes credit valuation adjustment.

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Instrument [Line Items]
Long-term Debt	The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2019 2018 Term loan - rates from 4.50% - 4.53% (a) and 4.01% - 4.60% (b) 2022 $ — $ 436.1 First Mortgage Bonds 3.95% 2049 425.0 — Tax-exempt First Mortgage Bonds - rates from 2.97% - 3.07% (a) and 1.52% - 1.92% (b) 2020 140.0 140.0 U.S. Government note 4.20% 2061 17.6 17.7 Unamortized deferred financing costs (5.7 ) (6.3 ) Unamortized debt discounts and premiums, net (2.7 ) (1.4 ) Total long-term debt at DP&L 574.2 586.1 Senior unsecured bonds 6.75% 2019 — 99.0 Senior unsecured bonds 7.25% 2021 380.0 780.0 Senior unsecured notes 4.35% 2029 400.0 — Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (5.8 ) (4.3 ) Unamortized debt discounts and premiums, net (1.1 ) (0.5 ) Total long-term debt 1,362.9 1,475.9 Less: current portion (139.6 ) (103.6 ) Long-term debt, net of current portion $ 1,223.3 $ 1,372.3 (a) Range of interest rates for the nine months ended September 30, 2019 . (b) Range of interest rates for the year ended December 31, 2018 . (c) Note payable to related party.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt	The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2019 2018 Term loan - rates from 4.50% - 4.53% (a) and 4.01% - 4.60% (b) 2022 $ — $ 436.1 First Mortgage Bonds 3.95% 2049 425.0 — Tax-exempt First Mortgage Bonds - rates from 2.97% - 3.07% (a) and 1.52% - 1.92% (b) 2020 140.0 140.0 U.S. Government note 4.20% 2061 17.6 17.7 Unamortized deferred financing costs (5.7 ) (6.3 ) Unamortized debt discounts and premiums, net (2.7 ) (1.4 ) Total long-term debt 574.2 586.1 Less: current portion (139.6 ) (4.6 ) Long-term debt, net of current portion $ 434.6 $ 581.5 (a) Range of interest rates for the nine months ended September 30, 2019 . (b) Range of interest rates for the year ended December 31, 2018 .

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Schedule of Effective Income Tax Rates	The following table details the effective tax rates for the three and nine months ended September 30, 2019 and 2018 . Three months ended Nine months ended September 30, September 30, 2019 2018 2019 2018 DPL (35.6)% 16.3% (9.8)% 15.2%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Schedule of Effective Income Tax Rates	The following table details the effective tax rates for the three and nine months ended September 30, 2019 and 2018 . Three months ended Nine months ended September 30, September 30, 2019 2018 2019 2018 DP&L (19.1)% 16.8% 4.7% 16.2%

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Entity Information [Line Items]
Schedule of Net Periodic Benefit Cost / (Income)	The net periodic benefit cost of the pension benefit plans for the three and nine months ended September 30, 2019 and 2018 was: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Service cost $ 0.9 $ 1.5 $ 2.7 $ 4.5 Interest cost 3.7 3.4 11.2 10.3 Expected return on plan assets (5.0 ) (5.3 ) (15.0 ) (15.9 ) Amortization of unrecognized: Prior service cost 0.3 0.3 0.9 0.8 Actuarial loss 1.1 1.6 3.2 4.8 Net periodic benefit cost $ 1.0 $ 1.5 $ 3.0 $ 4.5
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Schedule of Net Periodic Benefit Cost / (Income)	The net periodic benefit cost of the pension benefit plans for the three and nine months ended September 30, 2019 and 2018 was: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Service cost $ 0.9 $ 1.5 $ 2.7 $ 4.5 Interest cost 3.7 3.4 11.2 10.3 Expected return on plan assets (5.0 ) (5.3 ) (15.0 ) (15.9 ) Amortization of unrecognized: Prior service cost 0.4 0.4 1.3 1.1 Actuarial loss 1.8 2.4 5.3 7.1 Net periodic benefit cost $ 1.8 $ 2.4 $ 5.5 $ 7.1

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting Information [Line Items]
Financial Reporting for Reportable Business Segments	The following tables present financial information for DPL’s Utility reportable business segment: $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Three months ended September 30, 2019 Revenues from external customers $ 190.9 $ 8.1 $ — $ 199.0 Intersegment revenues 0.2 0.8 (1.0 ) — Total revenues $ 191.1 $ 8.9 $ (1.0 ) $ 199.0 Depreciation and amortization $ 17.4 $ 0.3 $ — $ 17.7 Interest expense $ 6.1 $ 12.2 $ — $ 18.3 Income / (loss) from continuing operations before income tax $ 37.7 $ (11.2 ) $ — $ 26.5 Cash capital expenditures $ 58.9 $ 0.1 $ — $ 59.0 $ in millions Utility Other (a) Adjustments and Eliminations DPL Consolidated Three Months Ended September 30, 2018 Revenues from external customers $ 198.5 $ 9.2 $ — $ 207.7 Intersegment revenues 0.2 0.7 (0.9 ) — Total revenues $ 198.7 $ 9.9 $ (0.9 ) $ 207.7 Depreciation and amortization $ 19.1 $ 0.6 $ — $ 19.7 Interest expense $ 5.8 $ 16.8 $ — $ 22.6 Income / (loss) from continuing operations before income tax $ 37.5 $ (17.7 ) $ — $ 19.8 Cash capital expenditures $ 20.5 $ 4.6 $ — $ 25.1 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2019 Revenues from external customers $ 569.4 $ 22.8 $ — $ 592.2 Intersegment revenues 0.8 2.4 (3.2 ) — Total revenues $ 570.2 $ 25.2 $ (3.2 ) $ 592.2 Depreciation and amortization $ 52.9 $ 1.2 $ — $ 54.1 Interest expense $ 19.9 $ 43.8 $ — $ 63.7 Loss on early extinguishment of debt $ — $ 44.9 $ — $ 44.9 Income / (loss) from continuing operations before income tax $ 108.8 $ (85.8 ) $ — $ 23.0 Cash capital expenditures $ 121.1 $ 1.3 $ — $ 122.4 $ in millions Utility Other (a) Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2018 Revenues from external customers $ 562.9 $ 28.6 $ — $ 591.5 Intersegment revenues 0.6 2.1 (2.7 ) — Total revenues $ 563.5 $ 30.7 $ (2.7 ) $ 591.5 Depreciation and amortization $ 56.5 $ 2.3 $ — $ 58.8 Interest expense $ 20.5 $ 53.9 $ — $ 74.4 Income / (loss) from continuing operations before income tax $ 73.9 $ (60.2 ) $ — $ 13.7 Cash capital expenditures $ 65.0 $ 10.8 $ — $ 75.8 (a) "Other" includes Cash capital expenditures related to assets of discontinued operations and held-for-sale businesses for the three and nine months ended September 30, 2018. Total Assets September 30, 2019 December 31, 2018 Utility $ 1,779.4 $ 1,819.6 All Other (a) 36.9 63.5 DPL Consolidated $ 1,816.3 $ 1,883.1 (a) "All Other" includes Total assets related to the assets of discontinued operations and held-for-sale businesses and Eliminations for all periods presented.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Disaggregation of Revenue [Table Text Block]	DPL's revenue from contracts with customers was $195.0 million and $195.1 million for the three months ended September 30, 2019 and 2018, respectively, and $576.5 million and $560.1 million for the nine months ended September 30, 2019 and 2018, respectively. The following table presents our revenue from contracts with customers and other revenue by segment for the three and nine months ended September 30, 2019 and 2018 : $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2019 Retail revenue Retail revenue from contracts with customers $ 170.5 $ — $ — $ 170.5 Other retail revenue (a) 3.8 — — 3.8 Wholesale revenue Wholesale revenue from contracts with customers 4.4 5.0 (0.2 ) 9.2 RTO ancillary revenue 11.0 0.1 — 11.1 Capacity revenue 1.1 1.1 — 2.2 Miscellaneous revenue from contracts with customers (b) — 2.0 — 2.0 Miscellaneous revenue 0.3 0.7 (0.8 ) 0.2 Total revenues $ 191.1 $ 8.9 $ (1.0 ) $ 199.0 Three Months Ended September 30, 2018 Retail revenue Retail revenue from contracts with customers $ 168.4 $ — $ (0.4 ) $ 168.0 Other retail revenue (a) 12.6 — — 12.6 Wholesale revenue Wholesale revenue from contracts with customers 4.9 5.6 — 10.5 RTO ancillary revenue 10.8 (0.1 ) — 10.7 Capacity revenue 2.0 1.7 — 3.7 Miscellaneous revenue from contracts with customers (b) — 2.2 — 2.2 Miscellaneous revenue — 0.5 (0.5 ) — Total revenues $ 198.7 $ 9.9 $ (0.9 ) $ 207.7 Nine months ended September 30, 2019 Retail revenue Retail revenue from contracts with customers $ 503.8 $ — $ — $ 503.8 Other retail revenue (a) 14.9 — — 14.9 Wholesale revenue Wholesale revenue from contracts with customers 12.8 11.4 (0.8 ) 23.4 RTO ancillary revenue 32.8 0.2 — 33.0 Capacity revenue 5.0 4.2 — 9.2 Miscellaneous revenue from contracts with customers (b) — 7.1 — 7.1 Miscellaneous revenue 0.9 2.3 (2.4 ) 0.8 Total revenues $ 570.2 $ 25.2 $ (3.2 ) $ 592.2 Nine months ended September 30, 2018 Retail revenue Retail revenue from contracts with customers $ 469.3 $ — $ (0.8 ) $ 468.5 Other retail revenue (a) 31.4 — — 31.4 Wholesale revenue Wholesale revenue from contracts with customers 24.6 16.7 — 41.3 RTO ancillary revenue 32.4 0.1 — 32.5 Capacity revenue 5.8 4.7 — 10.5 Miscellaneous revenue from contracts with customers (b) — 7.3 — 7.3 Miscellaneous revenue — 1.9 (1.9 ) — Total revenues $ 563.5 $ 30.7 $ (2.7 ) $ 591.5 (a) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. (b) Miscellaneous revenue from contracts with customers primarily includes revenues for various services provided by Miami Valley Lighting.
Subsidiaries [Member]
Disaggregation of Revenue [Table Text Block]	DP&L's revenue from contracts with customers was $187.0 million and $186.1 million for the three months ended September 30, 2019 and 2018, respectively, and $554.4 million and $532.1 million for the nine months ended September 30, 2019 and 2018, respectively. The following table presents our revenue from contracts with customers and other revenue for the three and nine months ended September 30, 2019 and 2018 : Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Retail revenue Retail revenue from contracts with customers $ 170.5 $ 168.4 $ 503.8 $ 469.3 Other retail revenue (a) 3.8 12.6 14.9 31.4 Wholesale revenue Wholesale revenue from contracts with customers 4.4 4.9 12.8 24.6 RTO ancillary revenue 11.0 10.8 32.8 32.4 Capacity revenue 1.1 2.0 5.0 5.8 Miscellaneous revenue 0.3 — 0.9 — Total revenues $ 191.1 $ 198.7 $ 570.2 $ 563.5 (a) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606.

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following table summarizes the major categories of assets and liabilities at the dates indicated: $ in millions September 30, 2019 December 31, 2018 Accounts receivable, net $ 6.8 $ 4.0 Taxes applicable to subsequent years 0.6 2.3 Prepayments and other current assets 0.9 2.4 Intangible assets, net of amortization 0.2 5.3 Total assets of the disposal group classified as assets of discontinued operations and held-for-sale businesses in the balance sheets $ 8.5 $ 14.0 Accounts payable $ 4.3 $ 3.9 Accrued taxes 2.4 3.1 Accrued and other current liabilities 3.2 5.2 Deferred income taxes (a) (33.2 ) (39.8 ) Taxes payable — 2.3 Accrued pension and other post-retirement benefits — 9.7 Asset retirement obligations 70.4 90.4 Other non-current liabilities 15.2 6.6 Total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets $ 62.3 $ 81.4 (a) Deferred income taxes represent the tax asset position of the discontinued group of components, which were netted with liabilities on DPL prior to classification as discontinued operations. The following table summarizes the revenues, operating costs, other expenses and income tax of discontinued operations for the periods indicated: Three months ended Nine months ended September 30, September 30, $ in millions 2019 2018 2019 2018 Revenues $ 10.1 $ 15.6 $ 41.0 $ 141.8 Operating costs and other expenses (10.5 ) (10.6 ) (8.2 ) (105.1 ) Income from discontinued operations (0.4 ) 5.0 32.8 36.7 Gain / (loss) from disposal of discontinued operations — 0.3 0.1 (1.6 ) Income tax expense from discontinued operations 0.1 1.0 7.1 5.9 Net income from discontinued operations $ (0.5 ) $ 4.3 $ 25.8 $ 29.2

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)employeesegment	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)mi²employeecustomergenerating_facilitysegment	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments | segment	1
Cash and Cash Equivalents, at Carrying Value	$ 36.8		$ 36.8		$ 90.5
Entity number of employees | employee	653		653
Employees under a collective bargaining agreement which expires in October-2011			57.00%
Excise taxes collected	$ 13	$ 13.8	$ 37.3	$ 39.2
Restricted Cash and Cash Equivalents, Current	17.6		17.6		21.2
Restricted Cash and Cash Equivalents	54.4	87.4	54.4	87.4	111.7		$ 24.9
Public Utilities, Property, Plant and Equipment, Generation or Processing	0		$ 0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Number of reportable segments | segment			1
Cash and Cash Equivalents, at Carrying Value	$ 14.4		$ 14.4		45
Approximate number of retail customers | customer			524,000
Service area, square miles | mi²			6,000
Number of Operating Segments | segment			1
Entity number of employees | employee	642		642
Employees under a collective bargaining agreement which expires in October-2011			58.00%
Number Of Generating Facilities | generating_facility			1
Excise taxes collected	$ 13	$ 13.8	$ 37.3	$ 39.2
Restricted Cash and Cash Equivalents, Current	17.6		17.6		21.2
Restricted Cash and Cash Equivalents	32		32		$ 66.2	$ 12.7	$ 5.6
Accounting Standards Update 2016-13 [Member]
Significant Accounting Policies [Line Items]
Accounts Receivable, before Allowance for Credit Loss, Current	70.2		70.2
Accounting Standards Update 2016-13 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Accounts Receivable, before Allowance for Credit Loss, Current	$ 72.1		$ 72.1

Supplemental Financial Inform_3

Supplemental Financial Information (Supplemental Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Supplemental Financial Information [Line Items]
Impairment of Long-Lived Assets Held-for-use			$ 0	$ 2.8
Gain (Loss) on Sale of Assets and Asset Impairment Charges			(0.9)	0.6
Customer receivables	$ 51.1		51.1		$ 55.8
Unbilled Revenue	15.2		15.2		16.8
Amounts due from partners in jointly owned stations	0.2		0.2		0
Due from PJM transmission settlement	2.4		2.4		16.5
Other	1.3		1.3		2.3
Provision for uncollectible accounts	(0.4)		(0.4)		(0.9)
Total accounts receivable, net	69.8		69.8		90.5
Fuel and limestone	3		3		1.9
Plant materials and supplies	10		10		8.3
Other	0		0		0.5
Total inventories, at average cost	13		13		10.7
Other Operating Income (Expense), Net	0	$ (1.6)	(0.9)	(14.6)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Gain (Loss) on Disposition of Business	0	0	0	12.4
Customer receivables	50		50		53.3
Unbilled Revenue	15.2		15.2		16.8
Amounts due from partners in jointly owned stations	3.2		3.2		2.3
Due from PJM transmission settlement	2.4		2.4		16.5
Other	1.3		1.3		2.4
Provision for uncollectible accounts	(0.4)		(0.4)		(0.9)
Total accounts receivable, net	71.7		71.7		90.4
Plant materials and supplies	9.8		9.8		7.1
Other	0		0		0.6
Total inventories, at average cost	9.8		9.8		$ 7.7
Other Operating Income (Expense) [Member]
Supplemental Financial Information [Line Items]
Gain (Loss) on Disposition of Business	0	0	0	11.7
Impairment of Long-Lived Assets Held-for-use	0	1.6	0	2.8
Other Cost and Expense, Operating	0	0	(0.9)	(0.1)
Other Operating Income (Expense), Net	$ 0	$ (1.6)	$ (0.9)	$ (14.6)

Supplemental Financial Inform_4

Supplemental Financial Information (Reclassification out of ACOI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	$ (18.3)	$ (22.6)	$ (63.7)	$ (74.4)
Tax expense	9.4	(3.1)	12.6	(1.5)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	(0.4)	5	32.8	36.7
Discontinued Operation, Tax Effect of Discontinued Operation	(0.1)	(1)	(7.1)	(5.9)
Nonoperating Income (Expense)	(18)	(22.1)	(105.4)	(80)
Net income	35.4	21	61.4	41.4
THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	(6.1)	(5.8)	(19.9)	(20.5)
Tax expense	7.2	(6.3)	(5.1)	(12)
Nonoperating Income (Expense)	(6.6)	(6.2)	(19.8)	(23)
Net income	44.9	31.2	103.7	61.9
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income	(0.8)	(0.1)	(1.2)	2.6
Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income	1.7	0.6	2	2
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	(0.3)	(0.3)	(0.9)	(0.9)
Tax expense	(0.1)	0.1	0	0.3
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	0	0	0	4.3
Discontinued Operation, Tax Effect of Discontinued Operation	(0.4)	0	(0.4)	(1.5)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	(0.4)	0	(0.4)	2.8
Net income	(0.4)	(0.2)	(0.9)	(0.6)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	0	(0.3)	(0.1)	(1.1)
Tax expense	0	0.1	0	0.6
Net income	0	(0.2)	(0.1)	(0.5)
Amortization of defined benefit pension items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax expense	(0.1)	(0.1)	(0.1)	(0.1)
Nonoperating Income (Expense)	0.1	0.2	0.2	0.5
Net income	0	0.1	0.1	0.4
Amortization of defined benefit pension items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax expense	0.9	(0.2)	(0.5)	(0.7)
Nonoperating Income (Expense)	0.8	1	2.6	3.2
Net income	$ 1.7	$ 0.8	$ 2.1	$ 2.5

Supplemental Financial Inform_5

Supplemental Financial Information (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				$ 2.2
Other comprehensive loss before reclassifications				(1)
Amounts reclassified from AOCI to earnings				(1.2)
Other comprehensive income / (loss)	$ (1)	$ 0		(2.2)	$ 3
Balance, end of period	0			0
THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				(35.3)
Other comprehensive loss before reclassifications				(0.9)
Amounts reclassified from AOCI to earnings				2
Other comprehensive income / (loss)	1.6	$ 0.6	$ 0.8	1.1	$ 2.5
Balance, end of period	(34.2)			(34.2)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				17
Other comprehensive loss before reclassifications				(1)
Amounts reclassified from AOCI to earnings				(1.3)
Other comprehensive income / (loss)				(2.3)
Balance, end of period	14.7			14.7
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				0.6
Other comprehensive loss before reclassifications				(0.9)
Amounts reclassified from AOCI to earnings				(0.1)
Other comprehensive income / (loss)				(1)
Balance, end of period	(0.4)			(0.4)
Change in unfunded pension obligation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				(14.8)
Other comprehensive loss before reclassifications				0
Amounts reclassified from AOCI to earnings				0.1
Other comprehensive income / (loss)				0.1
Balance, end of period	(14.7)			(14.7)
Change in unfunded pension obligation [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period				(35.9)
Other comprehensive loss before reclassifications				0
Amounts reclassified from AOCI to earnings				2.1
Other comprehensive income / (loss)				2.1
Balance, end of period	$ (33.8)			$ (33.8)

Regulatory Matters (Details)

Regulatory Matters (Details) - USD ($)	Mar. 01, 2019	Jan. 22, 2019	Sep. 30, 2019	Dec. 31, 2018
Requested Distribution Modernization Rider annual revenue through filing		$ 199,000,000
Regulatory Assets, Noncurrent			$ 154,700,000	$ 152,600,000
Unbilled Revenue			15,200,000	16,800,000
Due from PJM transmission settlement			2,400,000	16,500,000
Refund of eligible excess ADIT and any related regulatory liability as required by the PUCO			65,100,000
Refund of eligible excess ADIT and any related regulatory liability as required by the PUCO, including taxes			83,200,000
Reduction of Long-term regulatory liability related to deferred income taxes			23.4
Subsidiaries [Member]
Requested Distribution Modernization Rider annual revenue through filing		$ 199,000,000
Regulatory Assets, Noncurrent			154,700,000	152,600,000
Unbilled Revenue			15,200,000	16,800,000
Due from PJM transmission settlement			2,400,000	$ 16,500,000
Refund of eligible excess ADIT and any related regulatory liability as required by the PUCO	$ 65,100,000
Refund of eligible excess ADIT and any related regulatory liability as required by the PUCO, including taxes			83,200,000
Reduction of Long-term regulatory liability related to deferred income taxes			$ 23.4

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - Adjustments for New Accounting Pronouncement [Member] $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
AOCI reclassed to Retained Earnings before tax	$ 1.6
AOCI reclassed to Retained Earnings, net of tax	1
THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI reclassed to Retained Earnings before tax	1.7
AOCI reclassed to Retained Earnings, net of tax	$ 1.1

Fair Value (Fair Value and Cost

Fair Value (Fair Value and Cost of Non-Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Cost [Member]
Total Assets	$ 6.8	$ 7.1
Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Assets	6.8	7.1
Fair Value [Member]
Total Master Trust Assets, Fair Value	8.4	8.1
Total Assets	8.4	8.1
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	8.4	8.1
Total Assets	8.4	8.1
Money Market Funds [Member] | Cost [Member]
Total Master Trust Assets, Cost	0.2	0.4
Money Market Funds [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.2	0.4
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Money Market Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Equity Securities [Member] | Cost [Member]
Total Master Trust Assets, Cost	2.3	2.4
Equity Securities [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	2.3	2.4
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Equity Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Debt Securities [Member] | Cost [Member]
Total Master Trust Assets, Cost	4.1	4.1
Debt Securities [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	4.1	4.1
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.1	4
Debt Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.1	4
Hedge Funds [Member] | Cost [Member]
Total Master Trust Assets, Cost	0.1	0.1
Hedge Funds [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.1	0.1
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Hedge Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Cost [Member]
Total Master Trust Assets, Cost	0.1	0.1
Tangible Assets [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.1	0.1
Tangible Assets [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Debt [Member] | Cost [Member]
Debt, Cost	1,362.9	1,475.9
Debt [Member] | Cost [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt, Cost	574.2	586.1
Debt [Member] | Fair Value [Member]
Debt, Fair Value	1,451.3	1,519.6
Debt [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt, Fair Value	$ 631	$ 593.8

Fair Value (Fair Value of Asset

Fair Value (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Level 1 [Member]
Total Master Trust Assets, Fair Value	$ 0.2	$ 0.4
Total Derivative Assets	0	0
Total Assets	0.2	0.4
Total Liabilities	0	0
Level 1 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Total Derivative Assets	0	0
Total Assets	0.2	0.4
Total Liabilities	0	0
Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 2 [Member]
Total Master Trust Assets, Fair Value	8.2	7.7
Total Derivative Assets	0.2	1.5
Total Assets	8.4	9.2
Total Liabilities	1,433.7	1,501.9
Level 2 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0.2	1.5
Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	8.2	7.7
Total Derivative Assets	0.2	1.5
Total Assets	8.4	9.2
Total Liabilities	613.4	576.1
Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0.2	1.5
Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Total Derivative Assets	0	0
Total Assets	0	0
Total Liabilities	17.6	17.7
Level 3 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Total Derivative Assets	0	0
Total Assets	0	0
Total Liabilities	17.6	17.7
Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Fair Value [Member]
Total Master Trust Assets, Fair Value	8.4	8.1
Total Derivative Assets	0.2	1.5
Total Assets	8.6	9.6
Total Liabilities	1,451.3	1,519.6
Fair Value [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0.2	1.5
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	8.4	8.1
Total Derivative Assets	0.2	1.5
Total Assets	8.6	9.6
Total Liabilities	631	593.8
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0.2	1.5
Money Market Funds [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Money Market Funds [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Money Market Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Money Market Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.4
Equity Securities [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Equity Securities [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Equity Securities [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Equity Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.9	3.5
Debt Securities [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	4.1	4
Debt Securities [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.1	4
Debt Securities [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.1	4
Debt Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.1	4
Hedge Funds [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Hedge Funds [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Hedge Funds [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Hedge Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Tangible Assets [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.1	0.1
Debt [Member] | Level 1 [Member]
Debt	0	0
Debt [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt	0	0
Debt [Member] | Level 2 [Member]
Debt	1,433.7	1,501.9
Debt [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt	613.4	576.1
Debt [Member] | Level 3 [Member]
Debt	17.6	17.7
Debt [Member] | Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt	17.6	17.7
Debt [Member] | Fair Value [Member]
Debt	1,451.3	1,519.6
Debt [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt	$ 631	$ 593.8

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)Number_of_interest_rate_swaps	Mar. 29, 2018USD ($)
Sale of Derivative Instruments Interest Rate Swap				$ 60
Gain on sale of Derivative Instruments Interest Rate Swap		$ 0.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument, Number of Financial Covenants | Number_of_interest_rate_swaps			2
Sale of Derivative Instruments Interest Rate Swap				$ 60
Gain on sale of Derivative Instruments Interest Rate Swap	$ 0.8
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member]
Long-term Debt, Gross			$ 140
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Long-term Debt, Gross			140
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative, Notional Amount, Purchase (Sales), Net			140
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative, Notional Amount, Purchase (Sales), Net			$ 140

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities (Outstanding Derivative Instruments) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Mar. 29, 2018
Sale of Derivative Instruments Interest Rate Swap					$ (60)
Gain on sale of Derivative Instruments Interest Rate Swap		$ 0.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Sale of Derivative Instruments Interest Rate Swap					$ (60)
Gain on sale of Derivative Instruments Interest Rate Swap	$ 0.8
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative, Notional Amount, Purchase (Sales), Net			$ 140
Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Swap [Member]
Derivative, Notional Amount, Purchase (Sales), Net			140
Derivative Financial Instruments, Assets [Member]
Derivative Asset, Fair Value, Gross Asset			0.2	$ 1.5
Derivative, Collateral, Obligation to Return Securities			0	0
Derivative, Collateral, Obligation to Return Cash			0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral			0.2	1.5
Derivative Financial Instruments, Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value, Gross Asset			0.2	1.5
Derivative, Collateral, Obligation to Return Securities			0	0
Derivative, Collateral, Obligation to Return Cash			0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral			0.2	1.5
Cash Flow Hedging [Member] | Other Prepayments and Current Assets [Member] | Short-term Derivative Positions [Member] | Forward Contract Power [Member]
Derivative Asset, Fair Value, Gross Asset				0.9
Derivative, Collateral, Obligation to Return Securities				0
Derivative, Collateral, Obligation to Return Cash				0
Derivative Asset, Fair Value, Amount Offset Against Collateral				0.9
Cash Flow Hedging [Member] | Other Prepayments and Current Assets [Member] | Short-term Derivative Positions [Member] | Interest Rate Swap [Member]
Derivative Asset, Fair Value, Gross Asset			0.2
Derivative, Collateral, Obligation to Return Securities			0
Derivative, Collateral, Obligation to Return Cash			0
Derivative Asset, Fair Value, Amount Offset Against Collateral			0.2
Cash Flow Hedging [Member] | Other Prepayments and Current Assets [Member] | Short-term Derivative Positions [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Swap [Member]
Derivative Asset, Fair Value, Gross Asset			0.2	0.9
Derivative, Collateral, Obligation to Return Securities			0	0
Derivative, Collateral, Obligation to Return Cash			0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral			$ 0.2	0.9
Cash Flow Hedging [Member] | Other Deferred Asset [Member] | Long-term Derivative Positions [Member] | Interest Rate Swap [Member]
Derivative Asset, Fair Value, Gross Asset				0.6
Derivative, Collateral, Obligation to Return Securities				0
Derivative, Collateral, Obligation to Return Cash				0
Derivative Asset, Fair Value, Amount Offset Against Collateral				0.6
Cash Flow Hedging [Member] | Other Deferred Asset [Member] | Long-term Derivative Positions [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Swap [Member]
Derivative Asset, Fair Value, Gross Asset				0.6
Derivative, Collateral, Obligation to Return Securities				0
Derivative, Collateral, Obligation to Return Cash				0
Derivative Asset, Fair Value, Amount Offset Against Collateral				$ 0.6

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities (Gains or Losses Recognized in AOCI for the Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	$ 0.4	$ 0	$ 0.4	$ (2.8)
Net gains / (losses) associated with current period hedging transactions	0	0	0	0
Ending accumulated derivative gain / (loss) in AOCI	0	0	0	0
Portion expected to be reclassified to earnings in the next twelve months
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)
Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	15.3	17.4	$ 16.6	17.5
Net gains / (losses) associated with current period hedging transactions	(0.2)	0.1	(1)	0.4
Ending accumulated derivative gain / (loss) in AOCI	14.7	17.3	14.7	17.3
Portion expected to be reclassified to earnings in the next twelve months	(1.2)		$ (1.2)
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			11 months
THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	(0.3)	1.6	$ 0.6	1.4
Net gains / (losses) associated with current period hedging transactions	(0.1)	0	(0.9)	0.5
Ending accumulated derivative gain / (loss) in AOCI	(0.4)	1.4	(0.4)	1.4
Portion expected to be reclassified to earnings in the next twelve months	(0.2)		$ (0.2)
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			11 months
Interest Expense [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0	$ 0	0
Interest Expense [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.4)	(0.2)	(0.9)	(0.6)
Interest Expense [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	(0.2)	(0.1)	(0.5)
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.4)	0	(0.4)	2.8
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	$ 0	$ 0	$ 0	$ 0

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities (Fair Value and Balance Sheet Location (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Total Assets [Member]
Derivative Asset, Fair Value	$ 0.2	$ 1.5
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	0.2	1.5
Total Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	0.2	1.5
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	0.2	1.5
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member]
Derivative Asset, Fair Value	0.2
Derivative, Collateral, Obligation to Return Securities	0
Derivative, Collateral, Obligation to Return Cash	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	0.2
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	0.2	0.9
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 0.2	0.9
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member]
Derivative Asset, Fair Value		0.6
Derivative, Collateral, Obligation to Return Securities		0
Derivative, Collateral, Obligation to Return Cash		0
Derivative Asset, Fair Value, Amount Offset Against Collateral		0.6
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value		0.6
Derivative, Collateral, Obligation to Return Securities		0
Derivative, Collateral, Obligation to Return Cash		0
Derivative Asset, Fair Value, Amount Offset Against Collateral		$ 0.6

Debt (Narrative) (Details)

Debt (Narrative) (Details) $ in Millions	Jun. 06, 2019USD ($)	May 07, 2019USD ($)	Apr. 17, 2019USD ($)	Apr. 04, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2019USD ($)fiscal_quarterdebt_covenant	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Apr. 30, 2018USD ($)	Mar. 30, 2018USD ($)	Aug. 03, 2015USD ($)
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 125
Letter Of Credit Sublimit						75
Line of Credit Facility, Additional Borrowing Capacity						50
Long-term Line of Credit								$ 0
Proceeds from Issuance of Long-term Debt						821.7	$ 0
Retirement of long-term debt						$ 978	239.4
Debt Covenant, Debt to EBITDA Ratio, Maximum								7
Debt to EBITDA Ratio						5.68
Debt Covenant, Leverage Ratio, Maximum						0.67
Debt Covenant, Interest Coverage Ratio, Minimum						2.50		2.25
Interest Coverage Ratio						2.99
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 175
Letter Of Credit Sublimit						75
Line of Credit Facility, Additional Borrowing Capacity						100
Long-term Line of Credit								$ 0
Proceeds from Issuance of Long-term Debt						422.3	0
Retirement of long-term debt						$ 436.1	$ 63.3
Long Term Indebtedness, Less than or Equal to									$ 750
Debt Covenant, Interest Coverage Ratio, Minimum						2.50
3.95% Senior Notes due 2049 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount	$ 435
Long-term Debt, Gross						$ 425
Proceeds from Issuance of Long-term Debt	$ 425
Debt instrument interest percentage						3.95%
Senior unsecured due in October 2019 - 6.75% [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount				$ 99	$ 101
Long-term Debt, Gross								99			$ 200
Make Whole Premium				$ 1.5						$ 5.1
Debt instrument interest percentage					6.75%	6.75%
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount					$ 60
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount						$ 60
Long-term Debt, Gross						140		140
Debt Instrument, Face Amount												$ 200
Bank term loan due in July 2020 - rates from: 2.44% - 2.45% [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount					$ 70
Term Loan Maturing 2022 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross						$ 0		436.1
Revolving Credit Agreement and Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Number of financial covenants | debt_covenant						2
Revolving Credit Agreement and Standby Letters of Credit [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Number of financial covenants | debt_covenant						2
Number of prior quarters included in EBITDA to interest calculation | fiscal_quarter						4
Debt Covenant, Interest Coverage Ratio, Minimum						2.50
Interest Coverage Ratio						9.36
First Mortgage Bonds [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum						0.65			0.75
DPL Revolving Credit Agreement and Term Loan Maturing July 2020 [Member]
Debt Instrument [Line Items]
Number of financial covenants | debt_covenant						2
Number of prior quarters included in EBITDA to interest calculation | fiscal_quarter						4
Number of prior quarters included in debt to EBITDA ratio | fiscal_quarter						4
Ten Year Senior Unsecured Bonds At435 Maturing At April152029 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt			$ 400
Debt instrument interest percentage			4.35%
Ten Year Senior Unsecured Notes At725 Maturing At October152021 [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount		$ 400
Long-term Debt, Gross		380				$ 380		$ 780
Make Whole Premium		$ 41.4
Debt instrument interest percentage					7.25%	7.25%
Revolving Credit Facility [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum						0.67
Total Debt to Total Capitalization Ratio						0.58

Debt (Long-term Debt) (Details)

Debt (Long-term Debt) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	May 07, 2019	Apr. 17, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 30, 2018
Debt Instrument [Line Items]
Unamortized deferred finance costs	$ (5.8)				$ (4.3)
Unamortized debt discounts and premiums, net	(1.1)				(0.5)
Total long-term debt	1,362.9				1,475.9
Less: current portion	(139.6)				(103.6)
Long-term debt	1,223.3				1,372.3
Long-term Line of Credit					0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unamortized deferred finance costs	(5.7)				(6.3)
Unamortized deferred finance costs	(5.7)				(6.3)
Unamortized debt discounts and premiums, net	(2.7)				(1.4)
Unamortized debt discounts and premiums, net	(2.7)				(1.4)
Total long-term debt at subsidiary	574.2				586.1
Total long-term debt	574.2				586.1
Less: current portion	(139.6)				(4.6)
Long-term debt	$ 434.6				581.5
Long-term Line of Credit					0
Term Loan Maturing 2022 [Domain]
Debt Instrument [Line Items]
Debt instrument maturity year	Aug. 24, 2022
Term Loan Maturing 2022 [Domain] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	Aug. 24, 2022
Term Loan Maturing 2022 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 0				436.1
3.95% Senior Notes due 2049 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 425
Debt instrument maturity year	Jun. 15, 2049
Debt instrument interest percentage	3.95%
Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	Aug. 1, 2020
Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140				140
Debt instrument maturity year	Aug. 1, 2020
U.S. Government note maturing in February 2061 - 4.20% [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	Feb. 1, 2061
Debt instrument interest percentage	4.20%
U.S. Government note maturing in February 2061 - 4.20% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 17.6				17.7
Debt instrument maturity year	Feb. 1, 2061
Debt instrument interest percentage	4.20%
Senior unsecured due in October 2019 - 6.75% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross					99	$ 200
Debt instrument maturity year	Oct. 1, 2019
Debt instrument interest percentage	6.75%			6.75%
Ten Year Senior Unsecured Bonds At435 Maturing At April152029 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage			4.35%
Senior unsecured due in October 2021 - 7.25% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 380	$ 380			780
Debt instrument maturity year	Oct. 1, 2021
Debt instrument interest percentage	7.25%			7.25%
4.35% Senior Notes due 2029 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 400
Debt instrument maturity year	Apr. 15, 2029
Debt instrument interest percentage	4.35%
Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 15.6				$ 15.6
Debt instrument maturity year	Sep. 1, 2031
Debt instrument interest percentage	8.125%
Maximum [Member] | Term Loan Maturing 2022 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.53%
Debt Instrument, Interest Rate, Effective Percentage					4.60%
Maximum [Member] | Term Loan Maturing 2022 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.53%
Debt Instrument, Interest Rate, Effective Percentage					4.60%
Maximum [Member] | Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage					1.92%
Maximum [Member] | Zero Point Two Three To Zero Point Two Nine And Zero Point One Six To Zero Point Three Six Percentage Of Bonds Maturing In November Two Thousand Forty [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	3.07%
Maximum [Member] | Zero Point Two Three To Zero Point Two Nine And Zero Point One Six To Zero Point Three Six Percentage Of Bonds Maturing In November Two Thousand Forty [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	3.07%				1.92%
Minimum [Member] | Term Loan Maturing 2022 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage					4.01%
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Minimum [Member] | Term Loan Maturing 2022 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage					4.01%
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Minimum [Member] | Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage					1.52%
Minimum [Member] | Zero Point Two Three To Zero Point Two Nine And Zero Point One Six To Zero Point Three Six Percentage Of Bonds Maturing In November Two Thousand Forty [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	2.97%
Minimum [Member] | Zero Point Two Three To Zero Point Two Nine And Zero Point One Six To Zero Point Three Six Percentage Of Bonds Maturing In November Two Thousand Forty [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	2.97%				1.52%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Entity Information [Line Items]
Effective Income Tax Rate Reconciliation, at Combined Federal and State Statutory Income Tax Rate, Percent							21.60%
Estimated annual effective income tax rate							(10.10%)	16.80%
Effective Income Tax Rate Reconciliation, Including Discontinued Operations, Percent	(35.60%)			16.30%			(9.80%)	15.20%
Non-cash capital contribution	$ 2.7	$ (1.5)	$ 1.5	$ 3.5	$ (17.9)	$ 44.6	$ 2.7	$ 30.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Information [Line Items]
Effective income tax rates				16.80%				16.20%
Effective Income Tax Rate Reconciliation, at Combined Federal and State Statutory Income Tax Rate, Percent							21.60%
Estimated annual effective income tax rate							4.50%	17.10%
Effective Income Tax Rate Reconciliation, Including Discontinued Operations, Percent	(19.10%)						4.70%

Benefit Plans (Net Periodic Ben

Benefit Plans (Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Pension [Member]
Contributions by employer			$ 7.5	$ 7.5
Service cost	$ 0.9	$ 1.5	2.7	4.5
Interest cost	3.7	3.4	11.2	10.3
Expected return on assets	(5)	(5.3)	(15)	(15.9)
Prior service cost	0.3	0.3	0.9	0.8
Actuarial loss / (gain)	1.1	1.6	3.2	4.8
Net periodic benefit cost	1	1.5	3	4.5
Postretirement [Member]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	9		9		$ 9.2
THE DAYTON POWER AND LIGHT COMPANY [Member] | Pension [Member]
Contributions by employer			7.5	7.5
Service cost	0.9	1.5	2.7	4.5
Interest cost	3.7	3.4	11.2	10.3
Expected return on assets	(5)	(5.3)	(15)	(15.9)
Prior service cost	0.4	0.4	1.3	1.1
Actuarial loss / (gain)	1.8	2.4	5.3	7.1
Net periodic benefit cost	1.8	$ 2.4	5.5	$ 7.1
THE DAYTON POWER AND LIGHT COMPANY [Member] | Postretirement [Member]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 9		$ 9		$ 9.2

Shareholder's Equity (Details)

Shareholder's Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Non-cash capital contribution	$ 2.7	$ (1.5)	$ 1.5	$ 3.5	$ (17.9)	$ 44.6	$ 2.7	$ 30.2
Common Stock, Shares Authorized	1,500				1,500		1,500		1,500
Common stock, shares outstanding	1						1		1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized	50,000,000			50,000,000			50,000,000	50,000,000	50,000,000
Par value common shares (in USD per share)	$ 0.01			$ 0.01			$ 0.01	$ 0.01	$ 0.01
Common stock, shares outstanding	41,172,173						41,172,173		41,172,173
Proceeds from Contributions from Parent		$ (70)				$ 80	$ 0	$ 80
Payments of Ordinary Dividends, Common Stock							$ 90	$ 43.8

Contractual Obligations, Comm_2

Contractual Obligations, Commercial Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Due to third parties, current	$ 0	$ 0
AES Ohio Generation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	$ 21
Debt Obligation on 4.9% Equity Ownership [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Equity ownership interest	4.90%
Equity ownership interest aggregate cost	$ 67.2
Electric Generation Company [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Debt obligation	$ 1,371.3
Other OVEC Member [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Equity ownership interest	4.85%
Other OVEC Member [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Equity ownership interest	4.85%

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)mi²customersegment	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Total assets	$ 1,816.3	$ 1,883.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Segment Reporting Information [Line Items]
Total assets	$ 1,779.4	1,819.6
Number of Operating Segments | segment	1
Approximate number of retail customers | customer	524,000
Service area, square miles | mi²	6,000
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
Total assets	$ 1,779.4	1,819.6
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 36.9	$ 63.5

Business Segments (Segment Fina

Business Segments (Segment Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
External customer revenues	$ 199	$ 207.7	$ 592.2	$ 591.5
Intersegment revenues	0	0	0	0
Total revenues	199	207.7	592.2	591.5
Depreciation and amortization	17.7	19.7	54.1	58.8
Fuel Costs	5.2	4.6	13	12.7
Depreciation and amortization			34.2	62.4
Interest expense	18.3	22.6	63.7	74.4
Gain (Loss) on Extinguishment of Debt	0	0	(44.9)	(6.4)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	26.5	19.8	23	13.7
Net income / (loss) from continuing operations	35.9	16.7	35.6	12.2
Discontinued operations, net of tax	(0.5)	4.3	25.8	29.2
Net income/ (loss)	35.4	21	61.4	41.4
Capital expenditures	59	25.1	122.4	75.8
Total assets	1,816.3		1,816.3		$ 1,883.1
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
External customer revenues	190.9	198.5	569.4	562.9
Intersegment revenues	0.2	0.2	0.8	0.6
Total revenues	191.1	198.7	570.2	563.5
Depreciation and amortization	17.4	19.1	52.9	56.5
Interest expense	6.1	5.8	19.9	20.5
Gain (Loss) on Extinguishment of Debt			0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	37.7	37.5	108.8	73.9
Capital expenditures	58.9	20.5	121.1	65
Total assets	1,779.4		1,779.4		1,819.6
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
External customer revenues	8.1	9.2	22.8	28.6
Intersegment revenues	0.8	0.7	2.4	2.1
Total revenues	8.9	9.9	25.2	30.7
Depreciation and amortization	0.3	0.6	1.2	2.3
Interest expense	12.2	16.8	43.8	53.9
Gain (Loss) on Extinguishment of Debt			(44.9)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(11.2)	(17.7)	(85.8)	(60.2)
Capital expenditures	0.1	4.6	1.3	10.8
Total assets	36.9		36.9		63.5
Adjustments and Eliminations [Member]
Segment Reporting Information [Line Items]
External customer revenues	0	0	0	0
Intersegment revenues	(1)	(0.9)	(3.2)	(2.7)
Total revenues	(1)	(0.9)	(3.2)	(2.7)
Depreciation and amortization	0	0	0	0
Interest expense	0	0	0	0
Gain (Loss) on Extinguishment of Debt			0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	0	0	0	0
Capital expenditures	0	0	0	0
Subsidiaries [Member]
Segment Reporting Information [Line Items]
Gain (Loss) on Disposition of Business	0	0	0	(12.4)
Depreciation and amortization	17.4	19.1	52.9	56.5
Fuel Costs	0.6	0.1	2	1.7
Depreciation and amortization			52.9	56.5
Interest expense	6.1	5.8	19.9	20.5
Gain (Loss) on Extinguishment of Debt	0	0	0	(0.6)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	37.7	37.5	108.8	73.9
Net income/ (loss)	44.9	$ 31.2	103.7	$ 61.9
Total assets	$ 1,779.4		$ 1,779.4		$ 1,819.6

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer, Excluding Assessed Tax	$ 195	$ 195.1	$ 576.5	$ 560.1
Alternative Revenue Programs Accounts Receivable, Gross	0		0		$ 0
RTO Revenue	11.1	10.7	33	32.5
RTO Capacity Revenue	2.2	3.7	9.2	10.5
Revenues	199	207.7	592.2	591.5
Contract with Customer, Asset, Gross	66.3		66.3		72.6
Corporate, Non-Segment [Member]
RTO Revenue	0.1	(0.1)	0.2	0.1
RTO Capacity Revenue	1.1	1.7	4.2	4.7
Revenues	8.9	9.9	25.2	30.7
Adjustments and Eliminations [Member]
RTO Revenue	0	0	0	0
RTO Capacity Revenue	0	0	0	0
Revenues	(1)	(0.9)	(3.2)	(2.7)
Utility [Member]
RTO Revenue	11	10.8	32.8	32.4
RTO Capacity Revenue	1.1	2	5	5.8
Revenues	191.1	198.7	570.2	563.5
Subsidiaries [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	187	186.1	554.4	532.1
Alternative Revenue Programs Accounts Receivable, Gross	0		0		0
RTO Revenue	11	10.8	32.8	32.4
RTO Capacity Revenue	1.1	2	5	5.8
Revenues	191.1	198.7	570.2	563.5
Contract with Customer, Asset, Gross	65.2		65.2		$ 70.1
Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2	2.2	7.1	7.3
Other non-606 revenue	0.2	0	0.8	0
Other Revenues [Member] | Corporate, Non-Segment [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2	2.2	7.1	7.3
Other non-606 revenue	0.7	0.5	2.3	1.9
Other Revenues [Member] | Adjustments and Eliminations [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Other non-606 revenue	(0.8)	(0.5)	(2.4)	(1.9)
Other Revenues [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Other non-606 revenue	0.3	0	0.9	0
Other Revenues [Member] | Subsidiaries [Member]
Other non-606 revenue	0.3	0	0.9	0
Wholesale Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	9.2	10.5	23.4	41.3
Wholesale Revenue [Member] | Corporate, Non-Segment [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	5	5.6	11.4	16.7
Wholesale Revenue [Member] | Adjustments and Eliminations [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.2)	0	(0.8)	0
Wholesale Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	4.4	4.9	12.8	24.6
Wholesale Revenue [Member] | Subsidiaries [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	4.4	4.9	12.8	24.6
Retail Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	170.5	168	503.8	468.5
Other non-606 revenue	3.8	12.6	14.9	31.4
Retail Revenue [Member] | Corporate, Non-Segment [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Other non-606 revenue	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	(0.4)	0	(0.8)
Other non-606 revenue	0	0	0	0
Retail Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	170.5	168.4	503.8	469.3
Other non-606 revenue	3.8	12.6	14.9	31.4
Retail Revenue [Member] | Subsidiaries [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	170.5	168.4	503.8	469.3
Other non-606 revenue	$ 3.8	$ 12.6	$ 14.9	$ 31.4

Dispositions (Details)

Dispositions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 26.5	$ 19.8	$ 23	$ 13.7
Property, Plant and Equipment, Additions	59	25.1	122.4	75.8
Beckjord [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest				(11.7)
Property, Plant and Equipment, Additions				14.5
Subsidiaries [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business	0	0	0	(12.4)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 37.7	$ 37.5	$ 108.8	73.9
Subsidiaries [Member] | Beckjord [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest				(12.4)
Property, Plant and Equipment, Additions				$ 14.5

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	$ 0	$ 0.3	$ 0.1	$ (1.6)
Disposal Group, Including Discontinued Operation, Revenue	10.1	15.6	41	141.8
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	6.8		6.8			$ 4
Disposal Group, Including Discontinued Operations, Taxes Applicable to Subsequent Years	0.6		0.6			2.3
Disposal Group, Including Discontinued Operation, Other Assets, Current	0.9		0.9			2.4
Disposal Group, Including Discontinued Operation, Intangible Assets	0.2		0.2			5.3
Disposal Group, Including Discontinued Operation, Assets	8.5		8.5			14
Disposal Group, Including Discontinued Operation, Accounts Payable	4.3		4.3			3.9
Disposal Group, Including Discontinued Operation, Accrued Income Tax Payable	2.4		2.4			3.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Current	3.2		3.2			5.2
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities	(33.2)		(33.2)			(39.8)
Disposal Group, Including Discontinued Operation, Taxes Payable	0		0			2.3
Disposal Group, Including Discontinued Operation, Pension Plan Benefit Obligation	0		0			9.7
Asset Retirement Obligation, Held for Sale	70.4		70.4			90.4
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent	15.2		15.2			6.6
Disposal Group, Including Discontinued Operation, Liabilities	62.3		62.3			$ 81.4
Disposal Group, Including Discontinued Operation, Operating and Other Expenses	(10.5)	(10.6)	(8.2)	(105.1)
Disposal Group, Including Discontinued Operation, Asset Retirement Obligation, Revision of Estimate			22.5
Loss from discontinued operations before income taxes	(0.4)	5	32.8	36.7
Income tax expense from discontinued operations	0.1	1	7.1	5.9
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(0.5)	4.3	25.8	29.2
Cash Provided by (Used in) Operating Activities, Discontinued Operations	(0.5)	$ (7.2)	12.4	37.2
Cash flows from investing activities for discontinued operations	$ 0		$ 0	233.8
Subsidiaries [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long Term Indebtedness, Less than or Equal to					$ 750
AES Ohio Generation peakers [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax				$ (1.9)