DPL (DPL) 10-Q 6 Nov 20 2020 Q3 Quarterly report Financial data

Cover Statement

Cover Statement	9 Months Ended
	Sep. 30, 2020shares
Entity Information [Line Items]
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000787250
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Current Reporting Status	Yes
Document Type	10-Q
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity Registrant Name	DPL Inc.
Entity Incorporation, State or Country Code	OH
Entity File Number	1-9052
Entity Address, Address Line One	1065 Woodman Drive
Entity Address, City or Town	Dayton
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45432
City Area Code	937
Local Phone Number	259-7215
Entity Tax Identification Number	31-1163136
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	1
Subsidiaries [Member]
Entity Information [Line Items]
Entity Central Index Key	0000027430
Amendment Flag	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Registrant Name	THE DAYTON POWER AND LIGHT COMPANY
Entity Incorporation, State or Country Code	OH
Entity File Number	1-2385
Entity Address, Address Line One	1065 Woodman Drive
Entity Address, City or Town	Dayton
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45432
City Area Code	937
Local Phone Number	259-7215
Entity Tax Identification Number	31-0258470
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	41,172,173

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 178.8	$ 192.9	$ 505.1	$ 576.5
Operating costs and expenses
Net fuel cost	0.4	0.6	1.3	2
Utilities Operating Expense, Purchased Power	66	66.3	178	194.2
Operating expenses:
Operation and maintenance	47.9	42.5	138.7	136.9
Depreciation and amortization	18.6	17.7	54.8	54
Taxes other than income taxes	17.7	20.8	59.6	58.3
Other Operating Income (Expense), Net	0.1	0	0.1	0
Costs and Expenses	150.7	147.9	432.5	445.4
Operating income	28.1	45	72.6	131.1
Other income / (expense), net:
Interest expense	(17.1)	(18.3)	(55.4)	(63.7)
Gain (Loss) on Extinguishment of Debt	31.7	0	31.7	44.9
Other income / (expense)	1	0.4	0.9	3.2
Total other expense, net	(47.8)	(17.9)	(86.2)	(105.4)
Income / (loss) from continuing operations before income tax	(19.7)	27.1	(13.6)	25.7
Income tax benefit from continuing operations	(10.4)	(9.1)	(7.7)	(11.8)
Net income / (loss) from continuing operations	(9.3)	36.2	(5.9)	37.5
Income / (loss) from discontinued operations before income tax	1.4	(1)	(0.6)	30.1
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0	0	4.5	0.1
Income tax expense / (benefit) from discontinued operations	0.3	(0.2)	0.8	6.3
Net income / (loss) from discontinued operations	1.1	(0.8)	3.1	23.9
Net income / (loss)	(8.2)	35.4	(2.8)	61.4
Subsidiaries [Member]
Revenues	177	191.1	499.1	570.2
Operating costs and expenses
Net fuel cost	0.4	0.6	1.3	2
Utilities Operating Expense, Purchased Power	65.7	65.9	177.1	193.3
Operating expenses:
Operation and maintenance	47.8	42.2	137.7	135.2
Depreciation and amortization	18.2	17.4	53.7	52.9
Taxes other than income taxes	17.8	20.8	59.6	58.2
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.1	(0.1)	0.1	0
Costs and Expenses	150	146.8	429.5	441.6
Operating income	27	44.3	69.6	128.6
Other income / (expense), net:
Interest expense	(5.9)	(6.1)	(18.5)	(19.9)
Other income / (expense)	0.2	(0.5)	(1.4)	0.1
Total other expense, net	(5.7)	(6.6)	(19.9)	(19.8)
Income / (loss) from continuing operations before income tax	21.3	37.7	49.7	108.8
Income tax benefit from continuing operations	3.5	(7.2)	2.4	5.1
Net income / (loss)	$ 17.8	$ 44.9	$ 47.3	$ 103.7

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ (8.2)	$ 35.4	$ (2.8)	$ 61.4
Derivative activity:
Change in derivative fair value, net of income tax	0.1	(0.2)	0	(1)
Reclassification of earnings, net of income tax	(0.3)	(0.4)	(0.8)	(0.9)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives Related to Discontinued Operations, Net of Tax	0	(0.4)	0	(0.4)
Total change in fair value of derivatives	(0.2)	(1)	(0.8)	(2.3)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.3	0	0.8	0.1
Total change in unfunded pension obligation	0.3	0	0.8	0.1
Other comprehensive income / (loss)	0.1	(1)	0	(2.2)
Net comprehensive income / (loss)	(8.1)	34.4	(2.8)	59.2
Subsidiaries [Member]
Net income	17.8	44.9	47.3	103.7
Derivative activity:
Change in derivative fair value, net of income tax	0.2	(0.1)	0.1	(0.9)
Reclassification of earnings, net of income tax	(0.1)	0	(0.3)	(0.1)
Total change in fair value of derivatives	0.1	(0.1)	(0.2)	(1)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.8	1.7	2.4	2.1
Total change in unfunded pension obligation	0.8	1.7	2.4	2.1
Other comprehensive income / (loss)	0.9	1.6	2.2	1.1
Net comprehensive income / (loss)	$ 18.7	$ 46.5	$ 49.5	$ 104.8

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	$ 0	$ (0.1)	$ 0	$ 0.1
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	0	(0.1)	0.1	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives Related to Discontinued Operations, Tax	0	(0.4)	0	(0.4)
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	0	(0.1)	(0.1)	(0.1)
Subsidiaries [Member]
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	0	0	0	0.2
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	(0.1)	0	(0.1)	0
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	$ (0.2)	$ 0.9	$ (0.6)	$ (0.5)

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 43.5	$ 36.5
Restricted cash	0.1	10.5
Accounts receivable, net	68.2	67.9
Accounts Receivable, Allowance for Credit Loss, Current	3.2	0.4
Inventories	8.2	10.4
Taxes applicable to subsequent years	20	77.5
Regulatory assets, current	20.9	19.7
Income Taxes Receivable, Current	11.6	23.6
Prepayments and other current assets	5.4	7.6
Disposal Group, Including Discontinued Operation, Assets, Current	0	22.3
Total current assets	177.9	276
Property, plant & equipment:
Property, plant & equipment	1,805.9	1,701.9
Less: Accumulated depreciation and amortization	(402.8)	(362.6)
Property, plant and equipment, net of depreciation	1,403.1	1,339.3
Construction work in process	112	106.3
Total net property, plant & equipment	1,515.1	1,445.6
Other non-current assets:
Regulatory assets, non-current	177	173.8
Intangible assets, net of amortization	17.8	19.3
Other non-current assets	19.7	20
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	0	1.1
Total other non-current assets	214.5	214.2
Total assets	1,907.5	1,935.8
Current liabilities:
Current portion of long-term debt	90.2	283.8
Accounts payable	54.8	72.6
Accrued taxes	83.3	79.3
Accrued interest	18.8	11.4
Security deposits	18.7	20.7
Regulatory liabilities, current	19.8	27.9
Other current liabilities	21.6	21.2
Liabilities Held for Sale, Current	0	9
Total current liabilities	307.2	525.9
Non-current liabilities:
Long-term debt	1,392.9	1,223.3
Deferred taxes	173.4	133.7
Taxes payable	2.9	81.1
Regulatory liabilities, non-current	220.5	243.6
Pension, retiree and other benefits	69	79.9
Other deferred credits	18.2	11.8
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0	8.4
Total non-current liabilities	1,876.9	1,781.8
Commitments and contingencies
Common shareholder's equity:
Common stock	0	0
Other paid-in capital	2,468.8	2,370.7
Accumulated other comprehensive income	(3.6)	(3.6)
Retained Earnings (Accumulated Deficit)	(2,741.8)	(2,739)
Total common shareholder's equity	(276.6)	(371.9)
Total liabilities and shareholder's equity	$ 1,907.5	$ 1,935.8
Common Stock, Shares Authorized	1,500	1,500
Common stock, shares issued	1	1
Par value common shares (in USD per share)	$ 0.01
Subsidiaries [Member]
Current assets:
Cash and cash equivalents	$ 26.1	$ 10.8
Restricted cash	0.1	10.5
Accounts receivable, net	69.2	70.9
Accounts Receivable, Allowance for Credit Loss, Current	3.2	0.4
Inventories	8.2	10.4
Taxes applicable to subsequent years	19.7	77.4
Regulatory assets, current	20.9	19.7
Income Taxes Receivable, Current	32.8	35.7
Prepayments and other current assets	6.7	10.8
Total current assets	183.7	246.2
Property, plant & equipment:
Property, plant & equipment	2,409.5	2,333.6
Less: Accumulated depreciation and amortization	(1,025.2)	(1,012.7)
Property, plant and equipment, net of depreciation	1,384.3	1,320.9
Construction work in process	109.4	104.5
Total net property, plant & equipment	1,493.7	1,425.4
Other non-current assets:
Regulatory assets, non-current	177	173.8
Intangible assets, net of amortization	16.8	18.2
Other non-current assets	19.3	19.6
Total other non-current assets	213.1	211.6
Total assets	1,890.5	1,883.2
Current liabilities:
Current portion of long-term debt	0.2	179.8
Accounts payable	53.7	74.4
Accrued taxes	84.3	79.4
Accrued interest	6	1.4
Security deposits	18.5	20.6
Regulatory liabilities, current	19.8	27.9
Other current liabilities	28.7	16.3
Total current liabilities	211.2	399.8
Non-current liabilities:
Long-term debt	573.9	434.6
Deferred taxes	172.1	158.1
Taxes payable	2.8	82.3
Regulatory liabilities, non-current	220.5	243.6
Pension, retiree and other benefits	69	79.9
Other deferred credits	10.7	11.5
Total non-current liabilities	1,049	1,010
Commitments and contingencies
Common shareholder's equity:
Common stock	0.4	0.4
Other paid-in capital	724.4	617
Accumulated other comprehensive income	(34.7)	(36.9)
Retained Earnings (Accumulated Deficit)	(59.8)	(107.1)
Total common shareholder's equity	630.3	473.4
Total liabilities and shareholder's equity	$ 1,890.5	$ 1,883.2
Common Stock, Shares, Outstanding	41,172,173	41,172,173
Common Stock, Shares Authorized	50,000,000	50,000,000
Par value common shares (in USD per share)	$ 0.01

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Common Stock, Shares Authorized	1,500	1,500	1,500
Common stock, shares issued	1	1
Common stock, par value (in USD per share)	$ 0.01
Subsidiaries [Member]
Common Stock, Shares Authorized	50,000,000	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, 2020		Sep. 30, 2019
Cash flows from operating activities:
Net income	$ (2.8)		$ 61.4
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	55.1		34.2
Amortization of Debt Issuance Costs	4.4		4.3
Gain (Loss) on Extinguishment of Debt	31.7		44.9
Deferred income taxes	32.3		(8.7)
Gain (Loss) on Disposition of Business, Including Discontinued Operation	(4.5)		(0.1)
Changes in certain assets and liabilities:
Accounts receivable, net	(12.7)		(18)
Inventories	(5.5)		3.2
Taxes applicable to subsequent years	(57.8)		(56.2)
Deferred regulatory costs, net	17.1		(2.9)
Accounts payable	(24.6)		(5.1)
Accrued taxes payable / receivable	(63)		(71)
Accrued interest	7.4		12.9
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(10.8)		(9.3)
Other	2.4		1.1
Net Cash Provided by (Used in) Operating Activities	81.7		136.3
Cash flows from investing activities:
Capital expenditures	(128.7)		(122.4)
Payments for Removal Costs	(1)		0
Proceeds from Sale of Productive Assets	5.1	[1]	0
Other investing activities, net	(0.8)		(3.5)
Net cash used in investing activities	(125.4)		(125.9)
Cash flows from financing activities:
Payments of Deferred Finance Costs	(7.8)		(9.2)
Repayments of Lines of Credit	(219)		(35)
Proceeds from Issuance of Long-term Debt	555		821.7
Proceeds from Lines of Credit	165		133
Retirement of long-term debt, including early payment premium	(550.8)		(978)
Proceeds from Contributions from Parent	98		0
Proceeds from (Payments for) Other Financing Activities	(0.1)		(0.2)
Net cash provided by / (used in) financing activities	40.3		(67.7)
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(3.4)		(57.3)
Restricted Cash and Cash Equivalents	43.6		54.4
Supplemental cash flow information:
Interest paid, net of amounts capitalized	49.7		47.1
Non-cash financing and investing activities:
Accruals for capital expenditures	16.5		2.3
Non-cash Proceeds from Sale of Business	3		0
Non-cash capital contribution	0		2.7
Income Taxes Paid, Net	(51.9)		1.3
Subsidiaries [Member]
Cash flows from operating activities:
Net income	47.3		103.7
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	53.7		52.9
Amortization of Debt Issuance Costs	2.9		2.8
Deferred income taxes	(0.1)		(17.2)
Changes in certain assets and liabilities:
Accounts receivable, net	1.7		18.9
Inventories	2.1		(2.1)
Taxes applicable to subsequent years	57.7		54.3
Deferred regulatory costs, net	(17.1)		2.9
Accounts payable	(20.6)		(4.8)
Accrued taxes payable / receivable	(71.6)		(65.6)
Accrued interest	4.6		6
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(10.8)		(9.3)
Other	(0.1)		(3.6)
Net Cash Provided by (Used in) Operating Activities	49.7		138.9
Cash flows from investing activities:
Capital expenditures	(125.1)		(121.1)
Other investing activities, net	(0.7)		(3.5)
Net cash used in investing activities	(125.8)		(124.6)
Cash flows from financing activities:
Payments of Deferred Finance Costs	(1.2)		(4.6)
Repayments of Lines of Credit	(115)		0
Proceeds from Issuance of Long-term Debt	140		422.3
Proceeds from Lines of Credit	75		60
Retirement of long-term debt, including early payment premium	(140)		(436.1)
Proceeds from Contributions from Parent	150		0
Proceeds from (Payments for) Other Financing Activities	(0.1)		(0.1)
Net cash provided by / (used in) financing activities	81		(48.5)
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	4.9		(34.2)
Restricted Cash and Cash Equivalents	26.2		32
Supplemental cash flow information:
Interest paid, net of amounts capitalized	10.5		10.8
Proceeds from Income Tax Refunds	(0.1)		(19)
Non-cash financing and investing activities:
Accruals for capital expenditures	16.4		2
Payments of Ordinary Dividends, Common Stock	$ (27.7)		$ (90)
[1]	Proceeds from sale of assets include $5.1 million of proceeds received from AES during the nine months ended September 30, 2020 related to the 2019 sale of software previously recorded on AES Ohio Generation. There was no gain or loss recorded on the transaction.

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, Beginning Balance at Dec. 31, 2018	$ (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)	42.1
Net Income (Loss) Attributable to Parent								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	[1]
Stockholders' Equity, Other	0.1		(0.1)					(0.3)				0.3
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2019	(428.4)	0	2,372.1		1.8	(2,802.3)		474.4	0.4	711.8	(34.9)	(202.9)
Dividends, Common Stock, Cash										(90)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2018	(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	(2.2)							1.1
Net income/ (loss)	61.4							103.7
Proceeds from Contributions from Parent	0							0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	59.2							104.8
Non-cash capital contribution	2.7
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Sep. 30, 2019	(409.6)	$ 0	2,373.4		0	(2,783)		459.8	$ 0.4	621.9	(34.2)	(128.3)
Shares, Issued		1							41,172,173
Dividends, Common Stock, Cash								(70)		(70)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Mar. 31, 2019	(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)	[1]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2019	(446.8)	$ 0	2,370.6		1	(2,818.4)		433.3	$ 0.4	641.8	(35.8)	(173.1)
Shares, Issued		1							41,172,173
Dividends, Common Stock, Cash								(20)		(20)
Other Comprehensive Income (Loss), Net of Tax	(1)				(1)			1.6
Net income/ (loss)	35.4							44.9
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	[1]
Stockholders' Equity, Other	0.1		(0.1)					0		(0.1)		0.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Sep. 30, 2019	$ (409.6)	$ 0	2,373.4		0	(2,783)		$ 459.8	$ 0.4	621.9	(34.2)	(128.3)
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
Common Stock, Shares Authorized	1,500							50,000,000
Shares, Issued		1							41,172,173
Common Stock, Value, Issued	$ 0							$ 0.4
Additional Paid in Capital, Common Stock	2,370.7							617
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3.6)						$ 14.5	(36.9)					$ (0.4)
Retained Earnings (Accumulated Deficit)	(2,739)							(107.1)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2019	(371.9)	$ 0	2,370.7		(3.6)	(2,739)		473.4
Other Comprehensive Income (Loss), Net of Tax	(0.3)										0.4
Net income/ (loss)	1.9
Net Income (Loss) Attributable to Parent												11.7
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	1.6							12.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2020	(370.3)	0	2,370.7		(3.9)	(2,737.1)		485.5	$ 0.4	617	(36.5)	(95.4)
Dividends, Common Stock, Cash										(27.7)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2019	(371.9)	0	2,370.7		(3.6)	(2,739)		473.4
Other Comprehensive Income (Loss), Net of Tax	0						(0.8)	2.2					(0.2)
Net income/ (loss)	(2.8)							47.3
Proceeds from Contributions from Parent	(98)							(150)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(2.8)							49.5
Non-cash capital contribution	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Sep. 30, 2020	(276.6)	$ 0	2,468.8		(3.6)	(2,741.8)		630.3	$ 0.4	724.4	(34.7)	(59.8)
Shares, Issued		1							41,172,173
Dividends, Common Stock, Cash								(14.2)		(14.2)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Mar. 31, 2020	(370.3)	$ 0	2,370.7		(3.9)	(2,737.1)		485.5	$ 0.4	617	(36.5)	(95.4)
Other Comprehensive Income (Loss), Net of Tax					0.2						0.9
Net Income (Loss) Attributable to Parent						3.5						17.8
Proceeds from Contributions from Parent			(98)					(150)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	3.7							18.7
Non-cash capital contribution	98
Stockholders' Equity, Other								0.1		0.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2020	(268.6)	$ 0	2,468.7		(3.7)	(2,733.6)		640.1	$ 0.4	752.9	(35.6)	(77.6)
Shares, Issued		1							41,172,173
Dividends, Common Stock, Cash								(28.5)		(28.5)
Other Comprehensive Income (Loss), Net of Tax	0.1				0.1			0.9			0.9
Net income/ (loss)	(8.2)							17.8
Net Income (Loss) Attributable to Parent						(8.2)						17.8
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(8.1)							18.7
Non-cash capital contribution	0.1		0.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Sep. 30, 2020	$ (276.6)	$ 0	$ 2,468.8		$ (3.6)	$ (2,741.8)		$ 630.3	$ 0.4	$ 724.4	$ (34.7)	$ (59.8)
Common stock, par value (in USD per share)	$ 0.01							$ 0.01
Common Stock, Shares Authorized	1,500							50,000,000
Shares, Issued		1							41,172,173
Common Stock, Value, Issued	$ 0							$ 0.4
Additional Paid in Capital, Common Stock	2,468.8							724.4
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3.6)						$ 13.7	(34.7)					$ (0.6)
Retained Earnings (Accumulated Deficit)	$ (2,741.8)							$ (59.8)
[1]	Represents the conversion of a tax sharing payable to AES to contributed capital, as DP&L's

Overview and Summary of Signifi

Overview and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
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 530,000 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. DP&L's sales typically reflect the seasonal weather patterns and the growth of energy efficiency initiatives. However, the impacts of weather, energy efficiency programs and economic changes in customer demand were largely offset in 2019 by DP&L’s Decoupling Rider, which was in place from January 1, 2019 until December 18, 2019. See Note 3 – Regulatory Matters for more information. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DPL’s other primary subsidiary is MVIC. MVIC is our captive insurance company that provides insurance services to DP&L and our other subsidiaries. In prior periods, AES Ohio Generation was also a primary subsidiary. In 2020, AES Ohio Generation's only operating asset was an undivided interest in Conesville, which was sold in June 2020. See Note 13 – Discontinued Operations for more information. 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 631 people as of September 30, 2020, of which 630 were employed by DP&L. Approximately 59% of all DPL employees are under a collective bargaining agreement, which expired October 31, 2020. On October 29, 2020, DP&L reached a tentative agreement with the union. The ratification vote is set for November 9, 2020. The parties currently plan to work under the terms of the expired agreement until a new agreement is ratified. 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. 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, 2019. 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, 2020; our results of operations for the three and nine months ended September 30, 2020 and 2019, our cash flows for the nine months ended September 30, 2020 and 2019 and the changes in our equity for the three and nine months ended September 30, 2020 and 2019. 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, 2020 may not be indicative of our results that will be realized for the full year ending December 31, 2020. 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 credit losses 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 Sheets that reconcile to the total of such amounts as shown on the Condensed Consolidated Statements of Cash Flows: $ in millions September 30, 2020 December 31, 2019 Cash and cash equivalents $ 43.5 $ 36.5 Restricted cash 0.1 10.5 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 43.6 $ 47.0 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, 2020 and 2019 were $13.4 million and $13.0 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2020 and 2019 were $36.7 million and $37.3 million, respectively. New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements.
Subsidiaries [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 530,000 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. DP&L 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 Hutchings Coal generating facility, which is now closed. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. DP&L's sales typically reflect the seasonal weather patterns and the growth of energy efficiency initiatives. However, the impacts of weather, energy efficiency programs and economic changes in customer demand were largely offset in 2019 by DP&L’s Decoupling Rider, which was in place from January 1, 2019 until December 18, 2019. See Note 3 – Regulatory Matters for more information. 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 630 people as of September 30, 2020. Approximately 59% of DP&L employees are under a collective bargaining agreement, which expired October 31, 2020. On October 29, 2020, DP&L reached a tentative agreement with the union. The ratification vote is set for November 9, 2020. The parties currently plan to work under the terms of the expired agreement until a new agreement is ratified. 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, 2019. 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, 2020; our results of operations for the three and nine months ended September 30, 2020 and 2019, our cash flows for the nine months ended September 30, 2020 and 2019 and the changes in our equity for the three and nine months ended September 30, 2020 and 2019. 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, 2020 may not be indicative of our results that will be realized for the full year ending December 31, 2020. 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 credit losses 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 Sheets that reconcile to the total of such amounts as shown on the Condensed Statements of Cash Flows: $ in millions September 30, 2020 December 31, 2019 Cash and cash equivalents $ 26.1 $ 10.8 Restricted cash 0.1 10.5 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 26.2 $ 21.3 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, 2020 and 2019 were $13.4 million and $13.0 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2020 and 2019 were $36.7 million and $37.3 million, respectively. New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed financial statements.

Supplemental Financial Informat

Supplemental Financial Information	9 Months Ended
	Sep. 30, 2020
Supplemental Financial Information [Line Items]
Allowance for Credit Losses	The following table is a rollforward of our allowance for credit losses related to the accounts receivable balances for the nine months ended September 30, 2020: $ in millions Beginning Allowance Balance at January 1, 2020 Current Period Provision Write-offs Charged Against Allowances Recoveries Collected Ending Allowance Balance at September 30, 2020 Allowance for credit losses $ 0.4 $ 2.7 $ (3.5) $ 3.6 $ 3.2
Supplemental Financial Information	Supplemental Financial Information Accounts receivable are as follows at September 30, 2020 and December 31, 2019: September 30, December 31, $ in millions 2020 2019 Accounts receivable, net: Customer receivables $ 52.2 $ 45.7 Unbilled revenue 15.1 19.4 Amounts due from affiliates 0.2 0.3 Due from PJM transmission enhancement settlement 1.8 1.8 Other 2.1 1.1 Allowance for credit losses (3.2) (0.4) Total accounts receivable, net $ 68.2 $ 67.9 The following table is a rollforward of our allowance for credit losses related to the accounts receivable balances for the nine months ended September 30, 2020: $ in millions Beginning Allowance Balance at January 1, 2020 Current Period Provision Write-offs Charged Against Allowances Recoveries Collected Ending Allowance Balance at September 30, 2020 Allowance for credit losses $ 0.4 $ 2.7 $ (3.5) $ 3.6 $ 3.2 The allowance for credit losses primarily relates to utility customer receivables, including unbilled amounts. Expected credit loss estimates are developed by disaggregating customers into those with similar credit risk characteristics and using historical credit loss experience. In addition, we also consider how current and future economic conditions are expected to impact collectability, as applicable, including the economic impacts of the COVID-19 pandemic on our receivable balance as of September 30, 2020. Amounts are written off when reasonable collections efforts have been exhausted. On March 12, 2020, the PUCO issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers through September 1, 2020 due to the economic impacts of COVID-19. This order along with the economic impacts of COVID-19 has resulted in an increase in past due customer receivable balances, and thus the current period provision and the allowance for credit losses have increased during 2020. See Note 14 – Risks and Uncertainties for additional discussion of the COVID-19 pandemic. Inventories consist of materials and supplies at September 30, 2020 and December 31, 2019. Accumulated other comprehensive loss The amounts reclassified out of Accumulated Other Comprehensive Loss by component during the three and nine months ended September 30, 2020 and 2019 are as follows: Details about Accumulated Other Comprehensive Loss components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Gains and losses on cash flow hedges (Note 5): Interest expense $ (0.3) $ (0.3) $ (0.9) $ (0.9) Income tax expense / (benefit) — (0.1) 0.1 — Net of income taxes (0.3) (0.4) (0.8) (0.9) Income tax benefit from discontinued operations — (0.4) — (0.4) Amortization of defined benefit pension items (Note 8): Other expense 0.3 0.1 0.9 0.2 Income tax benefit — (0.1) (0.1) (0.1) Net of income taxes 0.3 — 0.8 0.1 Total reclassifications for the period, net of income taxes $ — $ (0.8) $ — $ (1.2) The changes in the components of Accumulated Other Comprehensive Loss during the nine months ended September 30, 2020 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligations Total Balance at January 1, 2020 $ 14.5 $ (18.1) $ (3.6) Other comprehensive income / (loss) before reclassifications — — — Amounts reclassified from AOCL to earnings (0.8) 0.8 — Net current period other comprehensive income / (loss) (0.8) 0.8 — Balance at September 30, 2020 $ 13.7 $ (17.3) $ (3.6)
Subsidiaries [Member]
Supplemental Financial Information [Line Items]
Allowance for Credit Losses	The following table is a rollforward of our allowance for credit losses related to the accounts receivable balances for the nine months ended September 30, 2020: $ in millions Beginning Allowance Balance at January 1, 2020 Current Period Provision Write-offs Charged Against Allowances Recoveries Collected Ending Allowance Balance at September 30, 2020 Allowance for credit losses $ 0.4 $ 2.7 $ (3.5) $ 3.6 $ 3.2 The allowance for credit losses primarily relates to utility customer receivables, including unbilled amounts. Expected credit loss estimates are developed by disaggregating customers into those with similar credit risk characteristics and using historical credit loss experience. In addition, we also consider how current and future economic conditions are expected to impact collectability, as applicable, including the economic impacts of the COVID-19 pandemic on our receivable balance as of September 30, 2020. Amounts are written off when reasonable collections efforts have been exhausted. On March 12, 2020, the PUCO issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers through September 1, 2020 due to the economic impacts of COVID-19. This order along with the economic impacts of COVID-19 has resulted in an increase in past due customer receivable balances, and thus the current period provision and the allowance for credit losses have increased during 2020. See Note 12 – Risks and Uncertainties for additional discussion of the COVID-19 pandemic.
Supplemental Financial Information	Supplemental Financial Information Accounts receivable are as follows at September 30, 2020 and December 31, 2019: September 30, December 31, $ in millions 2020 2019 Accounts receivable, net: Customer receivables $ 51.2 $ 45.0 Unbilled revenue 15.1 19.4 Amounts due from affiliates 2.0 3.9 Due from PJM transmission enhancement settlement 1.8 1.8 Other 2.3 1.2 Allowance for credit losses (3.2) (0.4) Total accounts receivable, net $ 69.2 $ 70.9 The following table is a rollforward of our allowance for credit losses related to the accounts receivable balances for the nine months ended September 30, 2020: $ in millions Beginning Allowance Balance at January 1, 2020 Current Period Provision Write-offs Charged Against Allowances Recoveries Collected Ending Allowance Balance at September 30, 2020 Allowance for credit losses $ 0.4 $ 2.7 $ (3.5) $ 3.6 $ 3.2 The allowance for credit losses primarily relates to utility customer receivables, including unbilled amounts. Expected credit loss estimates are developed by disaggregating customers into those with similar credit risk characteristics and using historical credit loss experience. In addition, we also consider how current and future economic conditions are expected to impact collectability, as applicable, including the economic impacts of the COVID-19 pandemic on our receivable balance as of September 30, 2020. Amounts are written off when reasonable collections efforts have been exhausted. On March 12, 2020, the PUCO issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers through September 1, 2020 due to the economic impacts of COVID-19. This order along with the economic impacts of COVID-19 has resulted in an increase in past due customer receivable balances, and thus the current period provision and the allowance for credit losses have increased during 2020. See Note 12 – Risks and Uncertainties for additional discussion of the COVID-19 pandemic. Inventories consist of materials and supplies at September 30, 2020 and December 31, 2019. Accumulated Other Comprehensive Loss The amounts reclassified out of Accumulated Other Comprehensive Loss by component during the three and nine months ended September 30, 2020 and 2019 are as follows: Details about Accumulated Other Comprehensive Loss components Affected line item in the Condensed Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Gains and losses on cash flow hedges (Note 5): Interest expense $ — $ — $ (0.2) $ (0.1) Income tax benefit (0.1) — (0.1) — Net of income taxes (0.1) — (0.3) (0.1) Amortization of defined benefit pension items (Note 8): Other expense 1.0 0.8 3.0 2.6 Income tax expense / (benefit) (0.2) 0.9 (0.6) (0.5) Net of income taxes 0.8 1.7 2.4 2.1 Total reclassifications for the period, net of income taxes $ 0.7 $ 1.7 $ 2.1 $ 2.0 The changes in the components of Accumulated Other Comprehensive Loss during the nine months ended September 30, 2020 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligations Total Balance at January 1, 2020 $ (0.4) $ (36.5) $ (36.9) Other comprehensive income before reclassifications 0.1 — 0.1 Amounts reclassified from AOCL to earnings (0.3) 2.4 2.1 Net current period other comprehensive income / (loss) (0.2) 2.4 2.2 Balance at September 30, 2020 $ (0.6) $ (34.1) $ (34.7)

Regulatory Matters (Notes)

Regulatory Matters (Notes)	9 Months Ended
	Sep. 30, 2020
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters ESP v. MRO and SEET Proceedings Ohio law requires utilities to file either an ESP or MRO plan to establish SSO rates. From November 1, 2017 through December 18, 2019, DP&L operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (ESP 3). On November 21, 2019, the PUCO issued a supplemental order modifying ESP 3, and as a result DP&L filed a Notice of Withdrawal of its ESP 3 Application and requested to revert to the ESP rates that were in effect prior to ESP 3. The Notice of Withdrawal was approved by the PUCO on December 18, 2019. The PUCO order required, among other things, DP&L to conduct both an ESP v. MRO Test to validate that the ESP is expected to be more favorable in the aggregate than what would be experienced under an MRO, and a prospective SEET, which were filed with the PUCO on April 1, 2020. DP&L is also subject to an annual retrospective SEET. On October 23, 2020, DP&L entered into a Stipulation and Recommendation (settlement) with the staff of the PUCO and various customers, and organizations representing customers of DP&L and certain other parties with respect to, among other matters, DP&L’s applications pending at the PUCO for (i) approval of DP&L’s plan to modernize its distribution grid (the Smart Grid Plan), (ii) findings that DP&L passed the SEET for 2018 and 2019, and (iii) findings that DP&L’s current ESP 1 satisfies the SEET and the more favorable in the aggregate (MFA) regulatory test. The settlement is subject to, and conditioned upon, approval by the PUCO. A hearing has been set for January 11, 2021 for consideration of this settlement. The settlement would provide, among other items, for the following: • Approval of the Smart Grid Plan outlined in the Smart Grid Plan application filed by DP&L with the PUCO, as modified by the terms of the settlement, including, subject to offsetting operational benefits and certain other conditions, a return on and recovery of up to $249.0 million of Smart Grid Plan Phase 1 capital investments and recovery of operational and maintenance expenses through DP&L’s existing Infrastructure Investment Rider for a term of four years, under an aggregate cap of $267.6 million on the amount of such investments and expenses that is recoverable, and an acknowledgement that DP&L may file a subsequent application with the PUCO within three years seeking approvals for Phase 2 of the Smart Grid Plan; • A commitment by DP&L to invest in a customer information system and supporting technologies during Phase 1 of the Smart Grid Plan, with DP&L recovering a return on and of prudently incurred capital investments and operational and maintenance expenses, including deferred operational and maintenance expense amounts, in a future rate case; • A determination that DP&L’s ESP 1 satisfies the prospective SEET and the MFA regulatory test; • A recommendation by parties to the settlement that the PUCO also finds that DP&L satisfies the retrospective SEET for 2018 and 2019; • A commitment by DP&L to file an application with the PUCO no later than October 1, 2023 for a new electric security plan that does not seek to implement certain non-bypassable charges, including those related to provider of last resort risks, stability, or financial integrity; and • DP&L shareholder funding, in an aggregate amount of approximately $30.0 million over four years, for certain economic development discounts, incentives, and grants to certain commercial and industrial customers, including hospitals and manufacturers, assistance for low-income customers as well as the residents and businesses of the City of Dayton, and promotion of solar and resiliency development within DP&L’s service territory. Certain parties which intervened in the ESP proceedings have filed petitions for rehearing of the recent PUCO ESP orders; some of which seek to eliminate DP&L’s RSC from the ESP 1 rates that are currently in place and others seek to re-implement the 2017 ESP, but without the DMR. We are unable to predict the outcomes of these petitions, but if these result in terms that are more adverse than DP&L's current ESP rate plan, it could have a material adverse effect on our results of operations, financial condition and cash flows. The parties signing the above-referenced settlement have agreed to withdraw their respective petitions if the settlement is approved by the PUCO without material modification. Decoupling On January 23, 2020 DP&L filed with the PUCO requesting approval to defer its decoupling costs consistent with the methodology approved in its Distribution Rate Case. If approved, deferral would be effective December 18, 2019 and going forward would reduce impacts of weather, energy efficiency programs and economic changes in customer demand. COVID-19 In response to the PUCO’s COVID-19 emergency orders, DP&L filed an Application on March 23, 2020, requesting waivers of certain rule and tariff requirements and deferral of certain costs and revenues including those related to deposits and reconnection fees, late payment fees, credit card fees; and waived or uncollected amounts associated with putting customers on payment plans. On May 20, 2020, the PUCO approved the application and required DP&L to file a plan outlining the timing and steps it plans to take in an effort to return to normal operations. The authorized deferral of those certain costs and revenues must be offset by COVID-19 related savings. DP&L filed its plan on July 15, 2020 and was approved by the PUCO on August 12, 2020. As a result, DP&L has recorded a $0.8 million regulatory asset as of September 30, 2020. Recovery of these deferrals will be addressed in a future rate proceeding. FERC Proceedings On November 15, 2018 the FERC issued a Notice of Proposed Rulemaking (NOPR) to address amortization of excess accumulated deferred income taxes resulting from the TCJA and their impact on transmission rates. Such notice requires all public utility transmission providers with stated transmission rates under an Open Access Transmission Tariff (OATT) to determine the amount of excess deferred income taxes caused by the TCJA. On March 3, 2020, DP&L filed an application before the FERC to change its transmission rate from a stated rate to a formula rate, which was accepted by the FERC and made effective as of May 3, 2020, subject to further proceeding and potential refunds. The formula rate includes adjustments to flow back over time the excess deferred income taxes caused by the TCJA. The NOPR, therefore, no longer applies to DP&L . The rate changes will increase revenues by approximately $4.1 million through the end of 2020 as of the effective date, subject to refund based on final approved rates.
Subsidiaries [Member]
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters ESP v. MRO and SEET Proceedings Ohio law requires utilities to file either an ESP or MRO plan to establish SSO rates. From November 1, 2017 through December 18, 2019, DP&L operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (ESP 3). On November 21, 2019, the PUCO issued a supplemental order modifying ESP 3, and as a result DP&L filed a Notice of Withdrawal of its ESP 3 Application and requested to revert to the ESP rates that were in effect prior to ESP 3. The Notice of Withdrawal was approved by the PUCO on December 18, 2019. The PUCO order required, among other things, DP&L to conduct both an ESP v. MRO Test to validate that the ESP is expected to be more favorable in the aggregate than what would be experienced under an MRO, and a prospective SEET, which were filed with the PUCO on April 1, 2020. DP&L is also subject to an annual retrospective SEET. On October 23, 2020, DP&L entered into a Stipulation and Recommendation (settlement) with the staff of the PUCO and various customers, and organizations representing customers of DP&L and certain other parties with respect to, among other matters, DP&L’s applications pending at the PUCO for (i) approval of DP&L’s plan to modernize its distribution grid (the Smart Grid Plan), (ii) findings that DP&L passed the SEET for 2018 and 2019, and (iii) findings that DP&L’s current ESP 1 satisfies the SEET and the more favorable in the aggregate (MFA) regulatory test. The settlement is subject to, and conditioned upon, approval by the PUCO. A hearing has been set for January 11, 2021 for consideration of this settlement. The settlement would provide, among other items, for the following: • Approval of the Smart Grid Plan outlined in the Smart Grid Plan application filed by DP&L with the PUCO, as modified by the terms of the settlement, including, subject to offsetting operational benefits and certain other conditions, a return on and recovery of up to $249.0 million of Smart Grid Plan Phase 1 capital investments and recovery of operational and maintenance expenses through DP&L’s existing Infrastructure Investment Rider for a term of four years, under an aggregate cap of $267.6 million on the amount of such investments and expenses that is recoverable, and an acknowledgement that DP&L may file a subsequent application with the PUCO within three years seeking approvals for Phase 2 of the Smart Grid Plan; • A commitment by DP&L to invest in a customer information system and supporting technologies during Phase 1 of the Smart Grid Plan, with DP&L recovering a return on and of prudently incurred capital investments and operational and maintenance expenses, including deferred operational and maintenance expense amounts, in a future rate case; • A determination that DP&L’s ESP 1 satisfies the prospective SEET and the MFA regulatory test; • A recommendation by parties to the settlement that the PUCO also finds that DP&L satisfies the retrospective SEET for 2018 and 2019; • A commitment by DP&L to file an application with the PUCO no later than October 1, 2023 for a new electric security plan that does not seek to implement certain non-bypassable charges, including those related to provider of last resort risks, stability, or financial integrity; and • DP&L shareholder funding, in an aggregate amount of approximately $30.0 million over four years, for certain economic development discounts, incentives, and grants to certain commercial and industrial customers, including hospitals and manufacturers, assistance for low-income customers as well as the residents and businesses of the City of Dayton, and promotion of solar and resiliency development within DP&L’s service territory. Certain parties which intervened in the ESP proceedings have filed petitions for rehearing of the recent PUCO ESP orders; some of which seek to eliminate DP&L’s RSC from the ESP 1 rates that are currently in place and others seek to re-implement the 2017 ESP, but without the DMR. We are unable to predict the outcomes of these petitions, but if these result in terms that are more adverse than DP&L's current ESP rate plan, it could have a material adverse effect on our results of operations, financial condition and cash flows. The parties signing the above-referenced settlement have agreed to withdraw their respective petitions if the settlement is approved by the PUCO without material modification. Decoupling On January 23, 2020 DP&L filed with the PUCO requesting approval to defer its decoupling costs consistent with the methodology approved in its Distribution Rate Case. If approved, deferral would be effective December 18, 2019 and going forward would reduce impacts of weather, energy efficiency programs and economic changes in customer demand. COVID-19 In response to the PUCO’s COVID-19 emergency orders, DP&L filed an Application on March 23, 2020, requesting waivers of certain rule and tariff requirements and deferral of certain costs and revenues including those related to deposits and reconnection fees, late payment fees, credit card fees; and waived or uncollected amounts associated with putting customers on payment plans. On May 20, 2020, the PUCO approved the application and required DP&L to file a plan outlining the timing and steps it plans to take in an effort to return to normal operations. The authorized deferral of those certain costs and revenues must be offset by COVID-19 related savings. DP&L filed its plan on July 15, 2020 and was approved by the PUCO on August 12, 2020. As a result, DP&L has recorded a $0.8 million regulatory asset as of September 30, 2020. Recovery of these deferrals will be addressed in a future rate proceeding. FERC Proceedings On November 15, 2018 the FERC issued a Notice of Proposed Rulemaking (NOPR) to address amortization of excess accumulated deferred income taxes resulting from the TCJA and their impact on transmission rates. Such notice requires all public utility transmission providers with stated transmission rates under an Open Access Transmission Tariff (OATT) to determine the amount of excess deferred income taxes caused by the TCJA. On March 3, 2020, DP&L filed an application before the FERC to change its transmission rate from a stated rate to a formula rate, which was accepted by the FERC and made effective as of May 3, 2020, subject to further proceeding and potential refunds. The formula rate includes adjustments to flow back over time the excess deferred income taxes caused by the TCJA. The NOPR, therefore, no longer applies to DP&L . The rate changes will increase revenues by approximately $4.1 million through the end of 2020 as of the effective date, subject to refund based on final approved rates.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019. Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities. September 30, 2020 December 31, 2019 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.3 $ 0.3 Equity securities 2.1 3.9 2.3 4.2 Debt securities 4.0 4.1 4.0 4.1 Hedge funds — — 0.1 0.1 Tangible assets — — 0.1 0.1 Total Assets $ 6.3 $ 8.2 $ 6.8 $ 8.8 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 1,393.1 $ 1,499.4 $ 1,363.1 $ 1,404.0 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, 2020 or 2019. 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. 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 equity investments. We recorded net unrealized gains / (losses) of $0.3 million and $(0.1) million during the three months ended September 30, 2020 and 2019, respectively, and $0.0 million and $0.6 million during the during the nine months ended September 30, 2020 and 2019, respectively. These amounts are included in "Other income" in our Condensed Consolidated Statements of Operations. 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, 2020 and December 31, 2019 and the respective category within the fair value hierarchy for DPL is as follows: $ in millions Fair value at September 30, 2020 (a) Fair value at December 31, 2019 (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 $ 0.3 $ — $ — $ 0.3 Equity securities — 3.9 — 3.9 — 4.2 — 4.2 Debt securities — 4.1 — 4.1 — 4.1 — 4.1 Hedge funds — — — — — 0.1 — 0.1 Tangible assets — — — — — 0.1 — 0.1 Total Master Trust assets 0.2 8.0 — 8.2 0.3 8.5 — 8.8 Derivative assets Interest rate hedges — — — — — 0.1 — 0.1 Total Derivative assets — — — — — 0.1 — 0.1 Total Assets $ 0.2 $ 8.0 $ — $ 8.2 $ 0.3 $ 8.6 $ — $ 8.9 Liabilities Long-term debt $ — $ 1,482.0 $ 17.4 $ 1,499.4 $ — $ 1,386.5 $ 17.5 $ 1,404.0 Total Liabilities $ — $ 1,482.0 $ 17.4 $ 1,499.4 $ — $ 1,386.5 $ 17.5 $ 1,404.0 (a) Includes credit valuation adjustment 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, the 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.
Subsidiaries [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	Fair ValueThe 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, 2020 and December 31, 2019. Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities. September 30, 2020 December 31, 2019 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.3 $ 0.3 Equity securities 2.1 3.9 2.3 4.2 Debt securities 4.0 4.1 4.0 4.1 Hedge funds — — 0.1 0.1 Tangible assets — — 0.1 0.1 Total assets $ 6.3 $ 8.2 $ 6.8 $ 8.8 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 574.1 $ 615.2 $ 574.4 $ 600.5 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, 2020 or 2019. 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. 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 equity investments. We recorded net unrealized gains / (losses) of $0.3 million and $(0.1) million during the three months ended September 30, 2020 and 2019, respectively, and $0.0 million and $0.6 million during the during the nine months ended September 30, 2020 and 2019, respectively. These amounts are included in "Other income" in our Condensed Statements of Operations. 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, 2020 and December 31, 2019 and the respective category within the fair value hierarchy for DP&L is as follows: $ in millions Fair value at September 30, 2020 (a) Fair value at December 31, 2019 (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 $ 0.3 $ — $ — $ 0.3 Equity securities — 3.9 — 3.9 — 4.2 — 4.2 Debt securities — 4.1 — 4.1 — 4.1 — 4.1 Hedge funds — — — — — 0.1 — 0.1 Tangible assets — — — — — 0.1 — 0.1 Total Master Trust assets 0.2 8.0 — 8.2 0.3 8.5 — 8.8 Derivative assets Interest rate hedges — — — — — 0.1 — 0.1 Total derivative assets — — — — — 0.1 — 0.1 Total assets $ 0.2 $ 8.0 $ — $ 8.2 $ 0.3 $ 8.6 $ — $ 8.9 Liabilities Long-term debt $ — $ 597.8 $ 17.4 $ 615.2 $ — $ 583.0 $ 17.5 $ 600.5 Total liabilities $ — $ 597.8 $ 17.4 $ 615.2 $ — $ 583.0 $ 17.5 $ 600.5 (a) Includes credit valuation adjustment 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, the 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, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities For further information on our derivative and hedge accounting policies, See Note 1 – Overview and Summary of Significant Accounting Policies – Financial Derivatives and Note 6 - Derivative Instruments and Hedging Activities of Item 8 – Financial Statements and Supplementary Data in our Form 10-K. Cash Flow Hedges In August 2020, the two interest rate swaps to hedge the variable interest on the $140.0 million variable interest rate tax-exempt First Mortgage Bonds expired, as the associated debt reached maturity. The interest rate swaps had a combined notional amount of $140.0 million and settled monthly based on a one-month LIBOR. The AOCL associated with the swaps was amortized out of AOCL into interest expense over the 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 AOCL into interest expense. The following tables provide information concerning gains or losses recognized in AOCL for the cash flow hedges for the three and nine months ended September 30, 2020 and 2019: Three months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Power Beginning accumulated derivative gains in AOCL $ 13.9 $ 15.3 $ 0.4 Net gains / (losses) associated with current period hedging transactions 0.1 (0.2) — Net gains reclassified to earnings Interest expense (0.3) (0.4) — Income from discontinued operations — — (0.4) Ending accumulated derivative gains in AOCL $ 13.7 $ 14.7 $ — Nine months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Power Beginning accumulated derivative gains in AOCL $ 14.5 $ 16.6 $ 0.4 Net losses associated with current period hedging transactions — (1.0) — Net gains reclassified to earnings Interest expense (0.8) (0.9) — Income from discontinued operations — — (0.4) Ending accumulated derivative gains in AOCL $ 13.7 $ 14.7 $ — Portion expected to be reclassified to earnings in the next twelve months $ (0.1) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 0 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: $ in millions (net of tax) Hedging Designation Balance sheet classification September 30, 2020 December 31, 2019 Interest rate swap Cash Flow Hedge Prepayments and other current assets $ — $ 0.1
Subsidiaries [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities For further information on our derivative and hedge accounting policies, See Note 1 – Overview and Summary of Significant Accounting Policies – Financial Derivatives and Note 6 - Derivative Instruments and Hedging Activities of Item 8 – Financial Statements and Supplementary Data in our Form 10-K. Cash Flow Hedges In August 2020, the two interest rate swaps to hedge the variable interest on the $140.0 million variable interest rate tax-exempt First Mortgage Bonds expired, as the associated debt reached maturity. The interest rate swaps had a combined notional amount of $140.0 million and settled monthly based on a one-month LIBOR. The AOCL associated with the swaps was amortized out of AOCL into interest expense over the life of the underlying debt. The following tables provide information concerning gains or losses recognized in AOCL for the cash flow hedges for the three and nine months ended September 30, 2020 and 2019: Three months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative losses in AOCL $ (0.7) $ (0.3) Net gains / (losses) associated with current period hedging transactions 0.2 (0.1) Net gains reclassified to earnings Interest expense (0.1) — Ending accumulated derivative losses in AOCL $ (0.6) $ (0.4) Nine months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains / (losses) in AOCL $ (0.4) $ 0.6 Net gains / (losses) associated with current period hedging transactions 0.1 (0.9) Net gains reclassified to earnings Interest expense (0.3) (0.1) Ending accumulated derivative losses in AOCL $ (0.6) $ (0.4) Portion expected to be reclassified to earnings in the next twelve months $ 0.6 Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 0 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: $ in millions (net of tax) Hedging Designation Balance sheet classification September 30, 2020 December 31, 2019 Interest rate swap Cash Flow Hedge Prepayments and other current assets $ — $ 0.1

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2020
Debt Instrument [Line Items]
Long-term Debt	Long-term Debt The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95% 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20% 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20% 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt at DP&L 574.1 574.4 Senior unsecured bonds 7.25% 2021 — 380.0 Senior unsecured bonds 4.125% 2025 415.0 — Senior unsecured bonds 4.35% 2029 400.0 400.0 Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (10.6) (5.9) Unamortized debt discounts and premiums, net (1.0) (1.0) Total long-term debt 1,393.1 1,363.1 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 1,392.9 $ 1,223.3 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. (c) Note payable to related party. Lines of credit At September 30, 2020 and December 31, 2019, DPL had outstanding borrowings on its line of credit of $90.0 million and $104.0 million, respectively. At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Consolidated Balance Sheet. On June 19, 2020 DPL closed a $415.0 million issuance of senior unsecured notes. These notes carry an interest rate of 4.125% and mature on July 1, 2025. Proceeds from the issuance and cash on hand were used to redeem in-full the remaining balance of $380.0 million of DPL's 7.25% senior unsecured notes. These bonds were redeemed at par plus accrued interest and a make-whole premium of $30.8 million on July 20, 2020. On June 1, 2020 DPL amended its secured revolving credit facility. As a result of the amendment, the borrowing limit was reduced from $125.0 million to $110.0 million, the Total Debt to EBITDA covenant was eliminated, the EBITDA to Interest Expense covenant was reduced from 2.25 to 1.00 to 1.70 to 1.00, increasing to 1.75 to 1.00 as of September 30, 2022 and 2.00 to 1.00 as of December 31, 2022, and a trailing-twelve months minimum EBITDA covenant of $125.0 million was added, increasing to $130.0 million as of September 30, 2022 and $150.0 million as of December 31, 2022. Starting with the quarter ended September 30, 2021, the borrowing limit will be reduced by $5.0 million per quarter should DPL’s Total Debt to EBITDA ratio calculated for the period of four consecutive quarters exceed 7.00 to 1.00. Long-term debt covenants and restrictions DPL’s revolving credit agreement has two financial covenants. The first financial covenant, a minimum EBITDA, calculated at the end of each fiscal quarter for the four prior fiscal quarters, of $125.0 million is required, stepping up to $130.0 million on September 30, 2022 and $150.0 million on December 31, 2022. As of September 30, 2020, this financial covenant was in compliance. 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 1.70 to 1.00, and steps up to 1.75 to 1.00 on September 30, 2022 and 2.00 to 1.00 as of December 31, 2022. As of September 30, 2020, this financial covenant was met with a ratio of 2.72 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. As a result, as of September 30, 2020, DPL was prohibited from making a distribution to its shareholder or making a loan to any of its affiliates (other than its subsidiaries). DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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.
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	Long-term Debt The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95 % 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20 % 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20 % 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt 574.1 574.4 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 573.9 $ 434.6 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. Line of credit At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Balance Sheet for DP&L. Long-term debt covenants and restrictions DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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, 2020
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, 2020 and 2019. Three months ended Nine months ended September 30, September 30, 2020 2019 2020 2019 DPL 55.2% (35.6)% 71.1% (9.8)% DPL’s effective combined state and federal income tax rate for all operations was 55.2% and 71.1% for the three and nine months ended September 30, 2020, respectively. This rate is higher than the combined federal and state statutory rate of 22.3% primarily due to the flowthrough of the net tax benefit related to the reversal of excess deferred taxes of DP&L and the reversal of an uncertain tax position; these benefits were partially offset by an adjustment to the deferred tax balances. For the nine months ended September 30, 2020, DPL’s current period tax benefit was calculated using the limitations prescribed in ASC 740-270-30-28 as DPL's year-to-date pre-tax loss exceeded the amount of the anticipated full-year pre-tax loss. DPL's income tax expense for the nine months ended September 30, 2019 was calculated using the estimated annual effective income tax rates for 2019 of (10.1)%. Management estimates the annual effective tax rate based on its forecast of annual pre-tax income. AES files federal and state income tax returns which consolidate DPL and its subsidiaries. Under a tax sharing agreement with AES, DPL is responsible for the income taxes associated with its own taxable income and records the provision for income taxes using a separate return method. Effective with the approval of DP&L's 2017 ESP, through November 21, 2019, DPL was restricted from making tax sharing payments to AES throughout the term of the DMR and amounts that would otherwise have been tax sharing liabilities were converted to deemed capital contributions. With the November 21, 2019 order from the PUCO that removed the DMR, this requirement was eliminated. During the nine months ended September 30, 2020, DPL received a payment from AES of $52.0 million against its tax receivable balance as part of a $150.0 million payment from AES. See Note 9 – Shareholder's Deficit for additional information.
Subsidiaries [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, 2020 and 2019. Three months ended Nine months ended September 30, September 30, 2020 2019 2020 2019 DP&L 16.4% (19.1)% 4.8% 4.7% DP&L’s effective combined state and federal income tax rate was 16.4% and 4.8% for the three and nine months ended September 30, 2020, respectively. This is different from the combined federal and state statutory rate of 22.3% primarily due to the net tax benefit related to the reversal of excess deferred taxes and the reversal of an uncertain tax position, which were partially offset by an adjustment to the deferred tax balances. DP&L's income tax expense for the nine months ended September 30, 2019 was calculated using the estimated annual effective income tax rates for 2019 of 4.5%. Management estimates the annual effective tax rate based on its forecast of annual pre-tax income.

Benefit Plans

Benefit Plans	9 Months Ended
	Sep. 30, 2020
Pension [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-month periods ended September 30, 2020 and 2019. 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, 2020 and 2019 was: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Service cost $ 0.9 $ 0.9 $ 2.8 $ 2.7 Interest cost 2.9 3.7 8.8 11.2 Expected return on plan assets (4.6) (5.0) (14.0) (15.0) Amortization of unrecognized: Prior service cost 0.3 0.3 0.8 0.9 Actuarial loss 1.5 1.1 4.6 3.2 Net periodic benefit cost $ 1.0 $ 1.0 $ 3.0 $ 3.0 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 $9.1 million at September 30, 2020 and $9.6 million at December 31, 2019 were not material to the financial statements in the periods covered by this report.
Subsidiaries [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-month periods ended September 30, 2020 and 2019. 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 former employees that were 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, 2020 and 2019 was: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Service cost $ 0.9 $ 0.9 $ 2.8 $ 2.7 Interest cost 2.9 3.7 8.8 11.2 Expected return on plan assets (4.6) (5.0) (14.0) (15.0) Amortization of unrecognized: Prior service cost 0.3 0.4 1.0 1.3 Actuarial loss 2.2 1.8 6.5 5.3 Net periodic benefit cost $ 1.7 $ 1.8 $ 5.1 $ 5.5 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 $9.1 million at September 30, 2020 and $9.6 million at December 31, 2019 were not material to the financial statements in the periods covered by this report.

Statement of Shareholders' Equi

Statement of Shareholders' Equity	9 Months Ended
	Sep. 30, 2020
Statement of Stockholders' Equity [Abstract]
Stockholders' Equity Note Disclosure	Shareholder's Deficit Capital Contributions from AES In DP&L's six-year 2017 ESP, the PUCO imposed restrictions on DPL making dividend payments to its parent company, AES, during the term of the ESP, as well as on making tax-sharing payments to AES during the term of the DMR. The PUCO also required 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 . With the November 21, 2019 order from the PUCO that removed the DMR and the subsequent approval of DP&L's ESP 1 rate plan, these requirements were eliminated. See Note 3 – Regulatory Matters in Item 8. — Financial Statements and Supplementary Data of our Form 10-K for additional information on changes to DP&L's ESP and the removal of the DMR. For the nine months ended September 30, 2019, AES made a capital contribution of $2.7 million by converting the amount owed to it by DPL related to tax-sharing payments for current tax liabilities. During the nine months ended September 30, 2020, DPL received $150.0 million in a cash contribution from AES, which DPL then used to make a $150.0 million capital contribution to DP&L . The contribution at DPL represented an equity capital contribution of $98.0 million and a payment of $52.0 million against its tax receivable. The proceeds from the capital contribution at DP&L will primarily be used for funding needs to support DP&L's capital expenditure program, mainly new investments in and upgrades to DP&L’s transmission and distribution system.

Contractual Obligations, Commer

Contractual Obligations, Commercial Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
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, 2020, DPL had $1.9 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, 2020 and December 31, 2019, 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, 2020, DP&L could be responsible for the repayment of 4.9%, or $63.4 million, of $1,294.3 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 had filed for bankruptcy protection and the bankruptcy court had approved that member's rejection of the OVEC arrangement and its related obligations. Subsequent to that decision, another entity has assumed that member's ownership interest and all related liabilities. 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, 2020, cannot be reasonably determined. Environmental Matters DPL’s and DP&L’s current and previously-owned 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 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.
Subsidiaries [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, 2020, DP&L could be responsible for the repayment of 4.9%, or $63.4 million, of $1,294.3 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 had filed for bankruptcy protection and the bankruptcy court had approved that member's rejection of the OVEC arrangement and its related obligations. Subsequent to that decision, another entity has assumed that member's ownership interest and all related liabilities. 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, 2020, cannot be reasonably determined. Environmental Matters DP&L’s current and previously-owned 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, 2020
Segment Reporting Information [Line Items]
Business Segments	Business Segments 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 approximately 530,000 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 DP&L’s Hutchings Coal generating facility, which was closed in 2013. This facility did not transfer to AES Ohio Generation as part of DP&L's Generation Separation on October 1, 2017. Thus, it is grouped within the Utility segment for segment reporting purposes. In addition, regulatory deferrals and collections, which include collections and amortization of fuel deferrals from 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. 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, 2020 Revenues from external customers $ 176.8 $ 2.0 $ — $ 178.8 Intersegment revenues 0.2 1.0 (1.2) — Total revenues $ 177.0 $ 3.0 $ (1.2) $ 178.8 Depreciation and amortization $ 18.2 $ 0.4 $ — $ 18.6 Interest expense $ 5.9 $ 11.2 $ — $ 17.1 Loss on early extinguishment of debt $ — $ 31.7 $ — $ 31.7 Income / (loss) from continuing operations before income tax $ 21.3 $ (41.0) $ — $ (19.7) Capital expenditures $ 44.6 $ 0.1 $ — $ 44.7 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Three Months Ended September 30, 2019 Revenues from external customers $ 190.9 $ 2.0 $ — $ 192.9 Intersegment revenues 0.2 0.8 (1.0) — Total revenues $ 191.1 $ 2.8 $ (1.0) $ 192.9 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 $ (10.6) $ — $ 27.1 Capital expenditures $ 58.9 $ 0.1 $ — $ 59.0 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2020 Revenues from external customers $ 498.4 $ 6.7 $ — $ 505.1 Intersegment revenues 0.7 2.7 (3.4) — Total revenues $ 499.1 $ 9.4 $ (3.4) $ 505.1 Depreciation and amortization $ 53.7 $ 1.1 $ — $ 54.8 Interest expense $ 18.5 $ 36.9 $ — $ 55.4 Loss on early extinguishment of debt $ — $ 31.7 $ — $ 31.7 Income / (loss) from continuing operations before income tax $ 49.7 $ (63.3) $ — $ (13.6) Capital expenditures $ 125.1 $ 3.6 $ — $ 128.7 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2019 Revenues from external customers $ 569.4 $ 7.1 $ — $ 576.5 Intersegment revenues 0.8 2.4 (3.2) — Total revenues $ 570.2 $ 9.5 $ (3.2) $ 576.5 Depreciation and amortization $ 52.9 $ 1.1 $ — $ 54.0 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 $ (83.1) $ — $ 25.7 Capital expenditures $ 121.1 $ 1.3 $ — $ 122.4 Total Assets September 30, 2020 December 31, 2019 Utility $ 1,890.5 $ 1,883.2 All Other (a) 17.0 52.6 DPL Consolidated $ 1,907.5 $ 1,935.8 (a) "All Other" includes Total assets related to the assets of discontinued operations and held-for-sale businesses and Eliminations for all periods presented. "All Other" Total assets at June 30, 2020 is primarily cash on hand from debt issuances.

Revenue (Notes)

Revenue (Notes)	9 Months Ended
	Sep. 30, 2020
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 $177.0 million and $188.9 million for the three months ended September 30, 2020 and 2019, respectively, and $492.3 million and $560.8 million for the nine months ended September 30, 2020 and 2019, 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, 2020 and 2019: $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2020 Retail revenue Retail revenue from contracts with customers Residential revenue $ 99.3 $ — $ — $ 99.3 Commercial revenue 32.2 — — 32.2 Industrial revenue 14.5 — — 14.5 Governmental revenue 9.9 — — 9.9 Other (a) 3.7 — — 3.7 Total retail revenue from contracts with customers 159.6 — — 159.6 Other retail revenue (b) 0.1 — — 0.1 Wholesale revenue Wholesale revenue from contracts with customers 3.2 — (0.2) 3.0 RTO ancillary revenue 11.5 (0.1) — 11.4 Capacity revenue 0.9 — — 0.9 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 2.1 — 2.1 Other miscellaneous revenue 1.7 1.0 (1.0) 1.7 Total revenues $ 177.0 $ 3.0 $ (1.2) $ 178.8 $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 107.5 $ — $ — $ 107.5 Commercial revenue 34.8 — — 34.8 Industrial revenue 13.7 — — 13.7 Governmental revenue 11.4 — — 11.4 Other (a) 3.1 — — 3.1 Total retail revenue from contracts with customers 170.5 — — 170.5 Other retail revenue (b) 3.8 — — 3.8 Wholesale revenue Wholesale revenue from contracts with customers 4.4 — (0.2) 4.2 RTO ancillary revenue 11.0 0.1 — 11.1 Capacity revenue 1.1 — — 1.1 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 2.0 — 2.0 Other miscellaneous revenue 0.3 0.7 (0.8) 0.2 Total revenues $ 191.1 $ 2.8 $ (1.0) $ 192.9 Nine months ended September 30, 2020 Retail revenue Retail revenue from contracts with customers Residential revenue $ 279.9 $ — $ — $ 279.9 Commercial revenue 87.6 — — 87.6 Industrial revenue 38.2 — — 38.2 Governmental revenue 27.7 — — 27.7 Other (a) 9.7 — — 9.7 Total retail revenue from contracts with customers 443.1 — — 443.1 Other retail revenue (b) 8.8 — — 8.8 Wholesale revenue Wholesale revenue from contracts with customers 7.7 — (0.7) 7.0 RTO ancillary revenue 32.3 — — 32.3 Capacity revenue 3.2 — — 3.2 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 6.7 — 6.7 Other miscellaneous revenue 4.0 2.7 (2.7) 4.0 Total revenues $ 499.1 $ 9.4 $ (3.4) $ 505.1 Nine months ended September 30, 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 313.9 $ — $ — $ 313.9 Commercial revenue 103.7 — — 103.7 Industrial revenue 43.5 — — 43.5 Governmental revenue 33.3 — — 33.3 Other (a) 9.4 — — 9.4 Total retail revenue from contracts with customers 503.8 — — 503.8 Other retail revenue (b) 14.9 — — 14.9 Wholesale revenue Wholesale revenue from contracts with customers 12.8 — (0.8) 12.0 RTO ancillary revenue 32.8 0.1 — 32.9 Capacity revenue 5.0 — — 5.0 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 7.1 — 7.1 Other miscellaneous revenue 0.9 2.3 (2.4) 0.8 Total revenues $ 570.2 $ 9.5 $ (3.2) $ 576.5 (a) "Other" primarily includes Wright-Patterson Air Force Base revenues, billing service fees from CRES providers and other miscellaneous retail revenues from contracts with customers. (b) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. (c) 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 $67.3 million and $65.1 million as of September 30, 2020 and December 31, 2019, respectively. Payment terms for all receivables from contracts with customers are typically within 30 days, though during the third quarter of 2020 DP&L implemented and offered extended payment plans to customers as a result of the pandemic.
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 $175.2 million and $187.0 million for the three months ended September 30, 2020 and 2019, respectively, and $486.3 million and $554.4 million for the nine months ended September 30, 2020 and 2019, respectively. The following table presents our revenue from contracts with customers and other revenue for the three and nine months ended September 30, 2020 and 2019: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 99.3 $ 107.5 $ 279.9 $ 313.9 Commercial revenue 32.2 34.8 87.6 103.7 Industrial revenue 14.5 13.7 38.2 43.5 Governmental revenue 9.9 11.4 27.7 33.3 Other (a) 3.7 3.1 9.7 9.4 Total retail revenue from contracts with customers 159.6 170.5 443.1 503.8 Other retail revenue (b) 0.1 3.8 8.8 14.9 Wholesale revenue Wholesale revenue from contracts with customers 3.2 4.4 7.7 12.8 RTO ancillary revenue 11.5 11.0 32.3 32.8 Capacity revenue 0.9 1.1 3.2 5.0 Miscellaneous revenue 1.7 0.3 4.0 0.9 Total revenues $ 177.0 $ 191.1 $ 499.1 $ 570.2 (a) "Other" primarily includes Wright-Patterson Air Force Base revenues, billing service fees from CRES providers and other miscellaneous retail revenues from contracts with customers. (b) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. The balances of receivables from contracts with customers were $66.3 million and $64.4 million as of September 30, 2020 and December 31, 2019, respectively. Payment terms for all receivables from contracts with customers are typically within 30 days, though during the third quarter of 2020 DP&L implemented and offered extended payment plans to customers as a result of the pandemic.

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Discontinued Operations Conesville - In May 2020, AEP, the operator of the formerly co-owned Conesville EGU, retired Conesville Unit 4 as planned. On June 5, 2020, DPL and AES Ohio Generation, together with AEP, completed the transfer of their interests in the retired Unit 4, including the associated environmental liabilities, to an unaffiliated third-party purchaser. As a result, DPL recognized a gain on the transfer of $4.5 million for the nine months ended September 30, 2020. For the transaction, DPL will make quarterly cash expenditures, totaling $4.0 million, through July 2022, of which $1.0 million has been paid through September 30, 2020. The transfer of Conesville Unit 4 was the last step in DPL's plan to exit its AES Ohio Generation business operations. Stuart and Killen - 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. On December 20, 2019, DPL and AES Ohio Generation, together with AES Ohio Generation's joint owners in the retired Stuart and Killen generating facilities, completed the transfer of the retired generating facilities, including the associated environmental liabilities, to an unaffiliated third-party purchaser. DPL determined that the transfers of Conesville, Stuart and Killen along with the sales of the Peaker Assets in 2018 and Miami Fort and Zimmer in 2017 constitute the disposal of a group of components, which, as a whole, represent a strategic shift to exit its AES Ohio Generation business. As such, the disposal of this group of components 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 date indicated: $ in millions December 31, 2019 Accounts receivable, net $ 18.0 Inventories 3.7 Taxes applicable to subsequent years 0.3 Prepayments and other current assets 0.3 Intangible assets, net of amortization 0.1 Other non-current assets 1.0 Total assets of the disposal group classified as assets of discontinued operations and held-for-sale businesses in the balance sheets $ 23.4 Accounts payable $ 5.6 Accrued taxes 0.3 Accrued and other current liabilities 3.1 Deferred income taxes (a) (6.5) Taxes payable 0.3 Asset retirement obligations 8.3 Other non-current liabilities 6.3 Total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets $ 17.4 (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 2020 2019 2020 2019 Revenues $ 0.9 $ 16.2 $ 23.3 $ 56.7 Operating costs and other expenses 0.5 (17.2) (23.9) (26.6) Income from discontinued operations 1.4 (1.0) (0.6) 30.1 Gain from disposal of discontinued operations — — 4.5 0.1 Income tax expense from discontinued operations 0.3 (0.2) 0.8 6.3 Net income from discontinued operations $ 1.1 $ (0.8) $ 3.1 $ 23.9 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 $1.5 million and $(1.7) million for the three months ended September 30, 2020 and 2019, respectively, and $5.1 million and $9.9 million for the nine months ended September 30, 2020 and 2019, respectively. Cash flows from investing activities for discontinued operations were $(0.4) million and $4.0 million, respectively, for the three and nine months ended September 30, 2020. There were no material cash flows from investing activities for the three and nine months ended September 30, 2019. AROs of Discontinued Operations Prior to the transfer of the retired Stuart and Killen generating facilities, the facilities carried 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 $22.5 million based on updated internal analyses that reduced estimated closure costs associated with these ash ponds and landfills. As these plants were no longer in service, the reduction to the ARO liability was recorded as a credit to depreciation and amortization expense in the same amount. The credit to depreciation and amortization expense is included in operating and other expenses of discontinued operations for the nine months ended September 30, 2019 in the table above.

Risk & Uncertainties (Notes)

Risk & Uncertainties (Notes)	9 Months Ended
	Sep. 30, 2020
Unusual Risk or Uncertainty [Line Items]
Risks and Uncertainties [Text Block]	Risks and Uncertainties COVID-19 Pandemic The COVID-19 pandemic has severely impacted global economic activity, including electricity and energy consumption, and caused significant volatility and negative pressure in financial markets. The global impact of the outbreak has been rapidly evolving and many countries, including the United States, have reacted by instituting quarantines, mandating business and school closures and social distancing measures as well as restricting travel. The State of Ohio has implemented, among other things, stay-at-home and other social distancing measures to slow the spread of the virus, which has impacted energy demand within our service territory, though the stay-at-home restrictions have now been lifted in our service territory. On March 12, 2020, the PUCO also issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers. This prohibition ended for DP&L on September 1, 2020. We are taking a variety of measures in response to the spread of COVID-19 to ensure our ability to transmit, distribute and sell electric energy, ensure the health and safety of our employees, contractors, customers and communities and provide essential services to the communities in which we operate. In addition to the impacts to demand within our service territory, we also have incurred and expect to continue to incur expenses relating to COVID-19, and such expenses may include those that relate to events outside of our control. As the economic impact of the COVID-19 pandemic started to materialize in Ohio in the second half of March and continued in the second and third quarters of 2020, the COVID-19 pandemic primarily impacted our retail sales demand as shown by the changes in weather-normalized volumes of kWh sold: Customer class For the three months ended September 30, 2020 compared to the same period in 2019 For the six months ended September 30, 2020 compared to the same period in 2019 (a) For the nine months ended September 30, 2020 compared to the same period in 2019 Commercial (4.8)% (9.4)% (7.0)% Industrial 0.9% (9.3)% (6.8)% Residential 11.0% 9.8% 6.0% (a) This period most closely approximates the duration of the economic impact on our sales demand as a result of the COVID-19 pandemic. We also have incurred, and expect to continue to incur, expenses relating to COVID-19; however, see Note 3 – Regulatory Matters for a discussion of regulatory measures, which partially mitigate the impact of these expenses. The magnitude and duration of the COVID-19 pandemic is unknown at this time and may have material and adverse effects on our results of operations, financial condition and cash flows in future periods.
Subsidiaries [Member]
Unusual Risk or Uncertainty [Line Items]
Risks and Uncertainties [Text Block]	Risks and Uncertainties COVID-19 Pandemic The COVID-19 pandemic has severely impacted global economic activity, including electricity and energy consumption, and caused significant volatility and negative pressure in financial markets. The global impact of the outbreak has been rapidly evolving and many countries, including the United States, have reacted by instituting quarantines, mandating business and school closures and social distancing measures as well as restricting travel. The State of Ohio has implemented, among other things, stay-at-home and other social distancing measures to slow the spread of the virus, which has impacted energy demand within our service territory, though the stay-at-home restrictions have now been lifted in our service territory. On March 12, 2020, the PUCO also issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers. This prohibition ended for DP&L on September 1, 2020. We are taking a variety of measures in response to the spread of COVID-19 to ensure our ability to transmit, distribute and sell electric energy, ensure the health and safety of our employees, contractors, customers and communities and provide essential services to the communities in which we operate. In addition to the impacts to demand within our service territory, we also have incurred and expect to continue to incur expenses relating to COVID-19, and such expenses may include those that relate to events outside of our control. As the economic impact of the COVID-19 pandemic started to materialize in Ohio in the second half of March and continued in the second and third quarters of 2020, the COVID-19 pandemic primarily impacted our retail sales demand as shown by the changes in weather-normalized volumes of kWh sold: Customer class For the three months ended September 30, 2020 compared to the same period in 2019 For the six months ended September 30, 2020 compared to the same period in 2019 (a) For the nine months ended September 30, 2020 compared to the same period in 2019 Commercial (4.8)% (9.4)% (7.0)% Industrial 0.9% (9.3)% (6.8)% Residential 11.0% 9.8% 6.0% (a) This period most closely approximates the duration of the economic impact on our sales demand as a result of the COVID-19 pandemic. We also have incurred, and expect to continue to incur, expenses relating to COVID-19; however, see Note 3 – Regulatory Matters for a discussion of regulatory measures, which partially mitigate the impact of these expenses. The magnitude and duration of the COVID-19 pandemic is unknown at this time and may have material and adverse effects on our results of operations, financial condition and cash flows in future periods.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2020
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 530,000 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. DP&L's sales typically reflect the seasonal weather patterns and the growth of energy efficiency initiatives. However, the impacts of weather, energy efficiency programs and economic changes in customer demand were largely offset in 2019 by DP&L’s Decoupling Rider, which was in place from January 1, 2019 until December 18, 2019. See Note 3 – Regulatory Matters for more information. DP&L sells its proportional share of energy and capacity from its investment in OVEC into the wholesale market. DPL’s other primary subsidiary is MVIC. MVIC is our captive insurance company that provides insurance services to DP&L and our other subsidiaries. In prior periods, AES Ohio Generation was also a primary subsidiary. In 2020, AES Ohio Generation's only operating asset was an undivided interest in Conesville, which was sold in June 2020. See Note 13 – Discontinued Operations for more information. 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 631 people as of September 30, 2020, of which 630 were employed by DP&L. Approximately 59% of all DPL employees are under a collective bargaining agreement, which expired October 31, 2020. On October 29, 2020, DP&L reached a tentative agreement with the union. The ratification vote is set for November 9, 2020. The parties currently plan to work under the terms of the expired agreement until a new agreement is ratified.
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. 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, 2019. 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, 2020; our results of operations for the three and nine months ended September 30, 2020 and 2019, our cash flows for the nine months ended September 30, 2020 and 2019 and the changes in our equity for the three and nine months ended September 30, 2020 and 2019. 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, 2020 may not be indicative of our results that will be realized for the full year ending December 31, 2020. 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 credit losses 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, 2020 and 2019 were $13.4 million and $13.0 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2020 and 2019 were $36.7 million and $37.3 million, respectively.
Recently Issued Accounting Standards	New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements.
Subsidiaries [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 530,000 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. DP&L 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 Hutchings Coal generating facility, which is now closed. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, health care, data management, manufacturing and defense. DP&L's sales typically reflect the seasonal weather patterns and the growth of energy efficiency initiatives. However, the impacts of weather, energy efficiency programs and economic changes in customer demand were largely offset in 2019 by DP&L’s Decoupling Rider, which was in place from January 1, 2019 until December 18, 2019. See Note 3 – Regulatory Matters for more information. 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 630 people as of September 30, 2020. Approximately 59% of DP&L employees are under a collective bargaining agreement, which expired October 31, 2020. On October 29, 2020, DP&L reached a tentative agreement with the union. The ratification vote is set for November 9, 2020. The parties currently plan to work under the terms of the expired agreement until a new agreement is ratified.
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, 2019. 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, 2020; our results of operations for the three and nine months ended September 30, 2020 and 2019, our cash flows for the nine months ended September 30, 2020 and 2019 and the changes in our equity for the three and nine months ended September 30, 2020 and 2019. 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, 2020 may not be indicative of our results that will be realized for the full year ending December 31, 2020. 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
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, 2020 and 2019 were $13.4 million and $13.0 million, respectively. The amounts of such taxes collected for the nine months ended September 30, 2020 and 2019 were $36.7 million and $37.3 million, respectively.
Recently Issued Accounting Standards	New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed financial statements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Related Party Transaction [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements.
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 Sheets that reconcile to the total of such amounts as shown on the Condensed Consolidated Statements of Cash Flows: $ in millions September 30, 2020 December 31, 2019 Cash and cash equivalents $ 43.5 $ 36.5 Restricted cash 0.1 10.5 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 43.6 $ 47.0
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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed consolidated financial statements.
Subsidiaries [Member]
Related Party Transaction [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	New accounting pronouncements adopted in 2020 – 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 2016-13, 2018-19, 2019-04, 2019-05, 2019-10, 2019-11, 2020-02, 2020-03 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments See discussion of the ASU below. January 1, 2020 See impact upon adoption of the standard below. On January 1, 2020, we adopted ASC 326 Financial Instruments - Credit Losses and its subsequent corresponding updates ("ASC 326"). The new standard updates the impairment model for financial assets measured at amortized cost, known as the Current Expected Credit Loss ("CECL") model. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities are required to use a new forward-looking "expected loss" model that generally results in the earlier recognition of an allowance for credit losses. For available-for-sale debt securities with unrealized losses, entities measure credit losses as it was done under previous GAAP, except that unrealized losses due to credit-related factors are now recognized as an allowance on the balance sheet with a corresponding adjustment to earnings in the income statement. We applied the modified retrospective method of adoption for ASC 326. Under this transition method, we applied the transition provisions starting at the date of adoption. The new current expected credit loss model primarily impacts the calculation of expected credit losses on our trade accounts receivable. The adoption of ASC 326 and application of CECL on our trade accounts receivable 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 2020-04, Reference Rate Form (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting The standard provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference to LIBOR or another reference rate expected to be discontinued by reference rate reform. This standard is effective for a limited period of time (March 12, 2020 - December 21, 2022). Effective for all entities March 12, 2020 - December 31, 2022 We are currently evaluating the impact of adopting the standard on our condensed financial statements.
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 Sheets that reconcile to the total of such amounts as shown on the Condensed Statements of Cash Flows: $ in millions September 30, 2020 December 31, 2019 Cash and cash equivalents $ 26.1 $ 10.8 Restricted cash 0.1 10.5 Cash, Cash Equivalents, and Restricted Cash, End of Period $ 26.2 $ 21.3

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	9 Months Ended
	Sep. 30, 2020
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable are as follows at September 30, 2020 and December 31, 2019: September 30, December 31, $ in millions 2020 2019 Accounts receivable, net: Customer receivables $ 52.2 $ 45.7 Unbilled revenue 15.1 19.4 Amounts due from affiliates 0.2 0.3 Due from PJM transmission enhancement settlement 1.8 1.8 Other 2.1 1.1 Allowance for credit losses (3.2) (0.4) Total accounts receivable, net $ 68.2 $ 67.9
Reclassification out of Accumulated Other Comprehensive Income	The amounts reclassified out of Accumulated Other Comprehensive Loss by component during the three and nine months ended September 30, 2020 and 2019 are as follows: Details about Accumulated Other Comprehensive Loss components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Gains and losses on cash flow hedges (Note 5): Interest expense $ (0.3) $ (0.3) $ (0.9) $ (0.9) Income tax expense / (benefit) — (0.1) 0.1 — Net of income taxes (0.3) (0.4) (0.8) (0.9) Income tax benefit from discontinued operations — (0.4) — (0.4) Amortization of defined benefit pension items (Note 8): Other expense 0.3 0.1 0.9 0.2 Income tax benefit — (0.1) (0.1) (0.1) Net of income taxes 0.3 — 0.8 0.1 Total reclassifications for the period, net of income taxes $ — $ (0.8) $ — $ (1.2)
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in the components of Accumulated Other Comprehensive Loss during the nine months ended September 30, 2020 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligations Total Balance at January 1, 2020 $ 14.5 $ (18.1) $ (3.6) Other comprehensive income / (loss) before reclassifications — — — Amounts reclassified from AOCL to earnings (0.8) 0.8 — Net current period other comprehensive income / (loss) (0.8) 0.8 — Balance at September 30, 2020 $ 13.7 $ (17.3) $ (3.6)
Subsidiaries [Member]
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable are as follows at September 30, 2020 and December 31, 2019: September 30, December 31, $ in millions 2020 2019 Accounts receivable, net: Customer receivables $ 51.2 $ 45.0 Unbilled revenue 15.1 19.4 Amounts due from affiliates 2.0 3.9 Due from PJM transmission enhancement settlement 1.8 1.8 Other 2.3 1.2 Allowance for credit losses (3.2) (0.4) Total accounts receivable, net $ 69.2 $ 70.9
Reclassification out of Accumulated Other Comprehensive Income	The amounts reclassified out of Accumulated Other Comprehensive Loss by component during the three and nine months ended September 30, 2020 and 2019 are as follows: Details about Accumulated Other Comprehensive Loss components Affected line item in the Condensed Statements of Operations Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Gains and losses on cash flow hedges (Note 5): Interest expense $ — $ — $ (0.2) $ (0.1) Income tax benefit (0.1) — (0.1) — Net of income taxes (0.1) — (0.3) (0.1) Amortization of defined benefit pension items (Note 8): Other expense 1.0 0.8 3.0 2.6 Income tax expense / (benefit) (0.2) 0.9 (0.6) (0.5) Net of income taxes 0.8 1.7 2.4 2.1 Total reclassifications for the period, net of income taxes $ 0.7 $ 1.7 $ 2.1 $ 2.0
Schedule of Accumulated Other Comprehensive Income (Loss)	The changes in the components of Accumulated Other Comprehensive Loss during the nine months ended September 30, 2020 are as follows: $ in millions Gains / (losses) on cash flow hedges Change in unfunded pension and postretirement benefit obligations Total Balance at January 1, 2020 $ (0.4) $ (36.5) $ (36.9) Other comprehensive income before reclassifications 0.1 — 0.1 Amounts reclassified from AOCL to earnings (0.3) 2.4 2.1 Net current period other comprehensive income / (loss) (0.2) 2.4 2.2 Balance at September 30, 2020 $ (0.6) $ (34.1) $ (34.7)

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019. Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities. September 30, 2020 December 31, 2019 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.3 $ 0.3 Equity securities 2.1 3.9 2.3 4.2 Debt securities 4.0 4.1 4.0 4.1 Hedge funds — — 0.1 0.1 Tangible assets — — 0.1 0.1 Total Assets $ 6.3 $ 8.2 $ 6.8 $ 8.8 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 1,393.1 $ 1,499.4 $ 1,363.1 $ 1,404.0
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at September 30, 2020 and December 31, 2019 and the respective category within the fair value hierarchy for DPL is as follows: $ in millions Fair value at September 30, 2020 (a) Fair value at December 31, 2019 (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 $ 0.3 $ — $ — $ 0.3 Equity securities — 3.9 — 3.9 — 4.2 — 4.2 Debt securities — 4.1 — 4.1 — 4.1 — 4.1 Hedge funds — — — — — 0.1 — 0.1 Tangible assets — — — — — 0.1 — 0.1 Total Master Trust assets 0.2 8.0 — 8.2 0.3 8.5 — 8.8 Derivative assets Interest rate hedges — — — — — 0.1 — 0.1 Total Derivative assets — — — — — 0.1 — 0.1 Total Assets $ 0.2 $ 8.0 $ — $ 8.2 $ 0.3 $ 8.6 $ — $ 8.9 Liabilities Long-term debt $ — $ 1,482.0 $ 17.4 $ 1,499.4 $ — $ 1,386.5 $ 17.5 $ 1,404.0 Total Liabilities $ — $ 1,482.0 $ 17.4 $ 1,499.4 $ — $ 1,386.5 $ 17.5 $ 1,404.0 (a) Includes credit valuation adjustment
Subsidiaries [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, 2020 and December 31, 2019. Further information about the fair value of our derivative instruments can be found in Note 5 – Derivative Instruments and Hedging Activities. September 30, 2020 December 31, 2019 $ in millions Cost Fair Value Cost Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.3 $ 0.3 Equity securities 2.1 3.9 2.3 4.2 Debt securities 4.0 4.1 4.0 4.1 Hedge funds — — 0.1 0.1 Tangible assets — — 0.1 0.1 Total assets $ 6.3 $ 8.2 $ 6.8 $ 8.8 Carrying Value Fair Value Carrying Value Fair Value Liabilities Long-term debt $ 574.1 $ 615.2 $ 574.4 $ 600.5
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at September 30, 2020 and December 31, 2019 and the respective category within the fair value hierarchy for DP&L is as follows: $ in millions Fair value at September 30, 2020 (a) Fair value at December 31, 2019 (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 $ 0.3 $ — $ — $ 0.3 Equity securities — 3.9 — 3.9 — 4.2 — 4.2 Debt securities — 4.1 — 4.1 — 4.1 — 4.1 Hedge funds — — — — — 0.1 — 0.1 Tangible assets — — — — — 0.1 — 0.1 Total Master Trust assets 0.2 8.0 — 8.2 0.3 8.5 — 8.8 Derivative assets Interest rate hedges — — — — — 0.1 — 0.1 Total derivative assets — — — — — 0.1 — 0.1 Total assets $ 0.2 $ 8.0 $ — $ 8.2 $ 0.3 $ 8.6 $ — $ 8.9 Liabilities Long-term debt $ — $ 597.8 $ 17.4 $ 615.2 $ — $ 583.0 $ 17.5 $ 600.5 Total liabilities $ — $ 597.8 $ 17.4 $ 615.2 $ — $ 583.0 $ 17.5 $ 600.5 (a) Includes credit valuation adjustment

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2020
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 AOCL for the cash flow hedges for the three and nine months ended September 30, 2020 and 2019: Three months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Power Beginning accumulated derivative gains in AOCL $ 13.9 $ 15.3 $ 0.4 Net gains / (losses) associated with current period hedging transactions 0.1 (0.2) — Net gains reclassified to earnings Interest expense (0.3) (0.4) — Income from discontinued operations — — (0.4) Ending accumulated derivative gains in AOCL $ 13.7 $ 14.7 $ — Nine months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Power Beginning accumulated derivative gains in AOCL $ 14.5 $ 16.6 $ 0.4 Net losses associated with current period hedging transactions — (1.0) — Net gains reclassified to earnings Interest expense (0.8) (0.9) — Income from discontinued operations — — (0.4) Ending accumulated derivative gains in AOCL $ 13.7 $ 14.7 $ — Portion expected to be reclassified to earnings in the next twelve months $ (0.1) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 0 Financial Statement Effect
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: $ in millions (net of tax) Hedging Designation Balance sheet classification September 30, 2020 December 31, 2019 Interest rate swap Cash Flow Hedge Prepayments and other current assets $ — $ 0.1
Subsidiaries [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 AOCL for the cash flow hedges for the three and nine months ended September 30, 2020 and 2019: Three months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative losses in AOCL $ (0.7) $ (0.3) Net gains / (losses) associated with current period hedging transactions 0.2 (0.1) Net gains reclassified to earnings Interest expense (0.1) — Ending accumulated derivative losses in AOCL $ (0.6) $ (0.4) Nine months ended September 30, 2020 September 30, 2019 Interest Interest $ in millions (net of tax) Rate Hedge Rate Hedge Beginning accumulated derivative gains / (losses) in AOCL $ (0.4) $ 0.6 Net gains / (losses) associated with current period hedging transactions 0.1 (0.9) Net gains reclassified to earnings Interest expense (0.3) (0.1) Ending accumulated derivative losses in AOCL $ (0.6) $ (0.4) Portion expected to be reclassified to earnings in the next twelve months $ 0.6 Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 0
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: $ in millions (net of tax) Hedging Designation Balance sheet classification September 30, 2020 December 31, 2019 Interest rate swap Cash Flow Hedge Prepayments and other current assets $ — $ 0.1

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Instrument [Line Items]
Long-term Debt	Long-term Debt The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95% 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20% 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20% 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt at DP&L 574.1 574.4 Senior unsecured bonds 7.25% 2021 — 380.0 Senior unsecured bonds 4.125% 2025 415.0 — Senior unsecured bonds 4.35% 2029 400.0 400.0 Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (10.6) (5.9) Unamortized debt discounts and premiums, net (1.0) (1.0) Total long-term debt 1,393.1 1,363.1 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 1,392.9 $ 1,223.3 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. (c) Note payable to related party. Lines of credit At September 30, 2020 and December 31, 2019, DPL had outstanding borrowings on its line of credit of $90.0 million and $104.0 million, respectively. At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Consolidated Balance Sheet. On June 19, 2020 DPL closed a $415.0 million issuance of senior unsecured notes. These notes carry an interest rate of 4.125% and mature on July 1, 2025. Proceeds from the issuance and cash on hand were used to redeem in-full the remaining balance of $380.0 million of DPL's 7.25% senior unsecured notes. These bonds were redeemed at par plus accrued interest and a make-whole premium of $30.8 million on July 20, 2020. On June 1, 2020 DPL amended its secured revolving credit facility. As a result of the amendment, the borrowing limit was reduced from $125.0 million to $110.0 million, the Total Debt to EBITDA covenant was eliminated, the EBITDA to Interest Expense covenant was reduced from 2.25 to 1.00 to 1.70 to 1.00, increasing to 1.75 to 1.00 as of September 30, 2022 and 2.00 to 1.00 as of December 31, 2022, and a trailing-twelve months minimum EBITDA covenant of $125.0 million was added, increasing to $130.0 million as of September 30, 2022 and $150.0 million as of December 31, 2022. Starting with the quarter ended September 30, 2021, the borrowing limit will be reduced by $5.0 million per quarter should DPL’s Total Debt to EBITDA ratio calculated for the period of four consecutive quarters exceed 7.00 to 1.00. Long-term debt covenants and restrictions DPL’s revolving credit agreement has two financial covenants. The first financial covenant, a minimum EBITDA, calculated at the end of each fiscal quarter for the four prior fiscal quarters, of $125.0 million is required, stepping up to $130.0 million on September 30, 2022 and $150.0 million on December 31, 2022. As of September 30, 2020, this financial covenant was in compliance. 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 1.70 to 1.00, and steps up to 1.75 to 1.00 on September 30, 2022 and 2.00 to 1.00 as of December 31, 2022. As of September 30, 2020, this financial covenant was met with a ratio of 2.72 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. As a result, as of September 30, 2020, DPL was prohibited from making a distribution to its shareholder or making a loan to any of its affiliates (other than its subsidiaries). DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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.
Schedule of Long-term Debt Instruments	The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95% 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20% 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20% 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt at DP&L 574.1 574.4 Senior unsecured bonds 7.25% 2021 — 380.0 Senior unsecured bonds 4.125% 2025 415.0 — Senior unsecured bonds 4.35% 2029 400.0 400.0 Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (10.6) (5.9) Unamortized debt discounts and premiums, net (1.0) (1.0) Total long-term debt 1,393.1 1,363.1 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 1,392.9 $ 1,223.3 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. (c) Note payable to related party.
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	Long-term Debt The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95 % 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20 % 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20 % 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt 574.1 574.4 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 573.9 $ 434.6 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. Line of credit At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Balance Sheet for DP&L. Long-term debt covenants and restrictions DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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.
Schedule of Long-term Debt Instruments	The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95 % 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20 % 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20 % 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt 574.1 574.4 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 573.9 $ 434.6 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019.

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and 2019. Three months ended Nine months ended September 30, September 30, 2020 2019 2020 2019 DPL 55.2% (35.6)% 71.1% (9.8)%
Subsidiaries [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, 2020 and 2019. Three months ended Nine months ended September 30, September 30, 2020 2019 2020 2019 DP&L 16.4% (19.1)% 4.8% 4.7%

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and 2019 was: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Service cost $ 0.9 $ 0.9 $ 2.8 $ 2.7 Interest cost 2.9 3.7 8.8 11.2 Expected return on plan assets (4.6) (5.0) (14.0) (15.0) Amortization of unrecognized: Prior service cost 0.3 0.3 0.8 0.9 Actuarial loss 1.5 1.1 4.6 3.2 Net periodic benefit cost $ 1.0 $ 1.0 $ 3.0 $ 3.0
Subsidiaries [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, 2020 and 2019 was: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Service cost $ 0.9 $ 0.9 $ 2.8 $ 2.7 Interest cost 2.9 3.7 8.8 11.2 Expected return on plan assets (4.6) (5.0) (14.0) (15.0) Amortization of unrecognized: Prior service cost 0.3 0.4 1.0 1.3 Actuarial loss 2.2 1.8 6.5 5.3 Net periodic benefit cost $ 1.7 $ 1.8 $ 5.1 $ 5.5

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 Revenues from external customers $ 176.8 $ 2.0 $ — $ 178.8 Intersegment revenues 0.2 1.0 (1.2) — Total revenues $ 177.0 $ 3.0 $ (1.2) $ 178.8 Depreciation and amortization $ 18.2 $ 0.4 $ — $ 18.6 Interest expense $ 5.9 $ 11.2 $ — $ 17.1 Loss on early extinguishment of debt $ — $ 31.7 $ — $ 31.7 Income / (loss) from continuing operations before income tax $ 21.3 $ (41.0) $ — $ (19.7) Capital expenditures $ 44.6 $ 0.1 $ — $ 44.7 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Three Months Ended September 30, 2019 Revenues from external customers $ 190.9 $ 2.0 $ — $ 192.9 Intersegment revenues 0.2 0.8 (1.0) — Total revenues $ 191.1 $ 2.8 $ (1.0) $ 192.9 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 $ (10.6) $ — $ 27.1 Capital expenditures $ 58.9 $ 0.1 $ — $ 59.0 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2020 Revenues from external customers $ 498.4 $ 6.7 $ — $ 505.1 Intersegment revenues 0.7 2.7 (3.4) — Total revenues $ 499.1 $ 9.4 $ (3.4) $ 505.1 Depreciation and amortization $ 53.7 $ 1.1 $ — $ 54.8 Interest expense $ 18.5 $ 36.9 $ — $ 55.4 Loss on early extinguishment of debt $ — $ 31.7 $ — $ 31.7 Income / (loss) from continuing operations before income tax $ 49.7 $ (63.3) $ — $ (13.6) Capital expenditures $ 125.1 $ 3.6 $ — $ 128.7 $ in millions Utility Other Adjustments and Eliminations DPL Consolidated Nine months ended September 30, 2019 Revenues from external customers $ 569.4 $ 7.1 $ — $ 576.5 Intersegment revenues 0.8 2.4 (3.2) — Total revenues $ 570.2 $ 9.5 $ (3.2) $ 576.5 Depreciation and amortization $ 52.9 $ 1.1 $ — $ 54.0 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 $ (83.1) $ — $ 25.7 Capital expenditures $ 121.1 $ 1.3 $ — $ 122.4 Total Assets September 30, 2020 December 31, 2019 Utility $ 1,890.5 $ 1,883.2 All Other (a) 17.0 52.6 DPL Consolidated $ 1,907.5 $ 1,935.8 (a) "All Other" includes Total assets related to the assets of discontinued operations and held-for-sale businesses and Eliminations for all periods presented. "All Other" Total assets at June 30, 2020 is primarily cash on hand from debt issuances.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2020
Disaggregation of Revenue [Table Text Block]	The following table presents our revenue from contracts with customers and other revenue by segment for the three and nine months ended September 30, 2020 and 2019: $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2020 Retail revenue Retail revenue from contracts with customers Residential revenue $ 99.3 $ — $ — $ 99.3 Commercial revenue 32.2 — — 32.2 Industrial revenue 14.5 — — 14.5 Governmental revenue 9.9 — — 9.9 Other (a) 3.7 — — 3.7 Total retail revenue from contracts with customers 159.6 — — 159.6 Other retail revenue (b) 0.1 — — 0.1 Wholesale revenue Wholesale revenue from contracts with customers 3.2 — (0.2) 3.0 RTO ancillary revenue 11.5 (0.1) — 11.4 Capacity revenue 0.9 — — 0.9 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 2.1 — 2.1 Other miscellaneous revenue 1.7 1.0 (1.0) 1.7 Total revenues $ 177.0 $ 3.0 $ (1.2) $ 178.8 $ in millions Utility Other Adjustments and Eliminations Total Three Months Ended September 30, 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 107.5 $ — $ — $ 107.5 Commercial revenue 34.8 — — 34.8 Industrial revenue 13.7 — — 13.7 Governmental revenue 11.4 — — 11.4 Other (a) 3.1 — — 3.1 Total retail revenue from contracts with customers 170.5 — — 170.5 Other retail revenue (b) 3.8 — — 3.8 Wholesale revenue Wholesale revenue from contracts with customers 4.4 — (0.2) 4.2 RTO ancillary revenue 11.0 0.1 — 11.1 Capacity revenue 1.1 — — 1.1 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 2.0 — 2.0 Other miscellaneous revenue 0.3 0.7 (0.8) 0.2 Total revenues $ 191.1 $ 2.8 $ (1.0) $ 192.9 Nine months ended September 30, 2020 Retail revenue Retail revenue from contracts with customers Residential revenue $ 279.9 $ — $ — $ 279.9 Commercial revenue 87.6 — — 87.6 Industrial revenue 38.2 — — 38.2 Governmental revenue 27.7 — — 27.7 Other (a) 9.7 — — 9.7 Total retail revenue from contracts with customers 443.1 — — 443.1 Other retail revenue (b) 8.8 — — 8.8 Wholesale revenue Wholesale revenue from contracts with customers 7.7 — (0.7) 7.0 RTO ancillary revenue 32.3 — — 32.3 Capacity revenue 3.2 — — 3.2 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 6.7 — 6.7 Other miscellaneous revenue 4.0 2.7 (2.7) 4.0 Total revenues $ 499.1 $ 9.4 $ (3.4) $ 505.1 Nine months ended September 30, 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 313.9 $ — $ — $ 313.9 Commercial revenue 103.7 — — 103.7 Industrial revenue 43.5 — — 43.5 Governmental revenue 33.3 — — 33.3 Other (a) 9.4 — — 9.4 Total retail revenue from contracts with customers 503.8 — — 503.8 Other retail revenue (b) 14.9 — — 14.9 Wholesale revenue Wholesale revenue from contracts with customers 12.8 — (0.8) 12.0 RTO ancillary revenue 32.8 0.1 — 32.9 Capacity revenue 5.0 — — 5.0 Miscellaneous revenue Miscellaneous revenue from contracts with customers (c) — 7.1 — 7.1 Other miscellaneous revenue 0.9 2.3 (2.4) 0.8 Total revenues $ 570.2 $ 9.5 $ (3.2) $ 576.5 (a) "Other" primarily includes Wright-Patterson Air Force Base revenues, billing service fees from CRES providers and other miscellaneous retail revenues from contracts with customers. (b) Other retail revenue primarily includes alternative revenue programs not accounted for under FASC 606. (c) 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]	The following table presents our revenue from contracts with customers and other revenue for the three and nine months ended September 30, 2020 and 2019: Three months ended Nine months ended September 30, September 30, $ in millions 2020 2019 2020 2019 Retail revenue Retail revenue from contracts with customers Residential revenue $ 99.3 $ 107.5 $ 279.9 $ 313.9 Commercial revenue 32.2 34.8 87.6 103.7 Industrial revenue 14.5 13.7 38.2 43.5 Governmental revenue 9.9 11.4 27.7 33.3 Other (a) 3.7 3.1 9.7 9.4 Total retail revenue from contracts with customers 159.6 170.5 443.1 503.8 Other retail revenue (b) 0.1 3.8 8.8 14.9 Wholesale revenue Wholesale revenue from contracts with customers 3.2 4.4 7.7 12.8 RTO ancillary revenue 11.5 11.0 32.3 32.8 Capacity revenue 0.9 1.1 3.2 5.0 Miscellaneous revenue 1.7 0.3 4.0 0.9 Total revenues $ 177.0 $ 191.1 $ 499.1 $ 570.2 (a) "Other" primarily includes Wright-Patterson Air Force Base revenues, billing service fees from CRES providers and other miscellaneous retail revenues from contracts with customers. (b) 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, 2020
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 date indicated: $ in millions December 31, 2019 Accounts receivable, net $ 18.0 Inventories 3.7 Taxes applicable to subsequent years 0.3 Prepayments and other current assets 0.3 Intangible assets, net of amortization 0.1 Other non-current assets 1.0 Total assets of the disposal group classified as assets of discontinued operations and held-for-sale businesses in the balance sheets $ 23.4 Accounts payable $ 5.6 Accrued taxes 0.3 Accrued and other current liabilities 3.1 Deferred income taxes (a) (6.5) Taxes payable 0.3 Asset retirement obligations 8.3 Other non-current liabilities 6.3 Total liabilities of the disposal group classified as liabilities of discontinued operations and held-for-sale businesses in the balance sheets $ 17.4 (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 2020 2019 2020 2019 Revenues $ 0.9 $ 16.2 $ 23.3 $ 56.7 Operating costs and other expenses 0.5 (17.2) (23.9) (26.6) Income from discontinued operations 1.4 (1.0) (0.6) 30.1 Gain from disposal of discontinued operations — — 4.5 0.1 Income tax expense from discontinued operations 0.3 (0.2) 0.8 6.3 Net income from discontinued operations $ 1.1 $ (0.8) $ 3.1 $ 23.9

Risk & Uncertainties (Tables)

Risk & Uncertainties (Tables)	9 Months Ended
	Sep. 30, 2020
Risks and Uncertainties [Abstract]
Unusual Risks and Uncertainties	As the economic impact of the COVID-19 pandemic started to materialize in Ohio in the second half of March and continued in the second and third quarters of 2020, the COVID-19 pandemic primarily impacted our retail sales demand as shown by the changes in weather-normalized volumes of kWh sold: Customer class For the three months ended September 30, 2020 compared to the same period in 2019 For the six months ended September 30, 2020 compared to the same period in 2019 (a) For the nine months ended September 30, 2020 compared to the same period in 2019 Commercial (4.8)% (9.4)% (7.0)% Industrial 0.9% (9.3)% (6.8)% Residential 11.0% 9.8% 6.0% (a) This period most closely approximates the duration of the economic impact on our sales demand as a result of the COVID-19 pandemic.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)employee	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)mi²employeecustomersegment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments | segment			1
Cash and Cash Equivalents, at Carrying Value	$ 43.5		$ 43.5		$ 36.5
Entity number of employees | employee	631		631
Employees under a collective bargaining agreement which expires in October-2011			59.00%
Excise taxes collected	$ 13.4	$ 13	$ 36.7	$ 37.3
Restricted Cash and Cash Equivalents, Current	0.1		0.1		10.5
Restricted Cash and Cash Equivalents	43.6	54.4	$ 43.6	54.4	47	$ 111.7
Subsidiaries [Member]
Significant Accounting Policies [Line Items]
Number of reportable segments | segment			1
Cash and Cash Equivalents, at Carrying Value	$ 26.1		$ 26.1		10.8
Approximate number of retail customers | customer			530,000
Service area, square miles | mi²			6,000
Number of Operating Segments | segment			1
Entity number of employees | employee	630		630
Employees under a collective bargaining agreement which expires in October-2011			59.00%
Excise taxes collected	$ 13.4	13	$ 36.7	37.3
Restricted Cash and Cash Equivalents, Current	0.1		0.1		10.5
Restricted Cash and Cash Equivalents	$ 26.2	$ 32	$ 26.2	$ 32	$ 21.3	$ 66.2

Supplemental Financial Inform_3

Supplemental Financial Information (Supplemental Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						$ 0
Accounts Receivable, Allowance for Credit Loss, Current	$ 3.2					3.2		$ 0.4
Customer receivables	52.2					52.2		45.7
Unbilled Revenue	15.1					15.1		19.4
Amounts due from partners in jointly owned stations	0.2					0.2		0.3
Due from PJM transmission settlement	1.8					1.8		1.8
Other	2.1					2.1		1.1
Provision for uncollectible accounts	(3.2)					(3.2)		(0.4)
Total accounts receivable, net	68.2					68.2		67.9
Total inventories, at average cost	8.2					8.2		10.4
Other Operating Income (Expense), Net	(0.1)		$ 0			(0.1)	$ 0
Accounts Receivable, Credit Loss Expense (Reversal)						2.7
Accounts Receivable, Allowance for Credit Loss, Writeoff						(3.5)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0
Other Comprehensive Income (Loss), Net of Tax	0.1	$ (0.3)	(1)		$ (0.4)	0	(2.2)
Accounts Receivable, Allowance for Credit Loss, Recovery						3.6
Subsidiaries [Member]
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0.1
Accounts Receivable, Allowance for Credit Loss, Current	3.2					3.2		0.4
Customer receivables	51.2					51.2		45
Unbilled Revenue	15.1					15.1		19.4
Amounts due from partners in jointly owned stations	2					2		3.9
Due from PJM transmission settlement	1.8					1.8		1.8
Other	2.3					2.3		1.2
Provision for uncollectible accounts	(3.2)					(3.2)		(0.4)
Total accounts receivable, net	69.2					69.2		70.9
Total inventories, at average cost	8.2					8.2		$ 10.4
Accounts Receivable, Credit Loss Expense (Reversal)						2.7
Accounts Receivable, Allowance for Credit Loss, Writeoff						3.5
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(2.1)
Other Comprehensive Income (Loss), Net of Tax	$ 0.9		$ 1.6	$ (0.9)	$ 0.4	2.2	$ 1.1
Amortization of defined benefit pension items [Member]
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(0.8)
Other Comprehensive Income (Loss), Net of Tax						0.8
Amortization of defined benefit pension items [Member] | Subsidiaries [Member]
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(2.4)
Other Comprehensive Income (Loss), Net of Tax						2.4
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0.8
Other Comprehensive Income (Loss), Net of Tax						(0.8)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Subsidiaries [Member]
Supplemental Financial Information [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0.1
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0.3
Other Comprehensive Income (Loss), Net of Tax						$ (0.2)

Supplemental Financial Inform_4

Supplemental Financial Information (Reclassification out of ACOI) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	$ (17.1)		$ (18.3)		$ (55.4)	$ (63.7)
Tax expense	10.4		9.1		7.7	11.8
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	1.4		(1)		(0.6)	30.1
Discontinued Operation, Tax Effect of Discontinued Operation	(0.3)		0.2		(0.8)	(6.3)
Nonoperating Income (Expense)	(47.8)		(17.9)		(86.2)	(105.4)
Net income / (loss)	(8.2)	$ 1.9	35.4	$ 42.1	(2.8)	61.4
Subsidiaries [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	(5.9)		(6.1)		(18.5)	(19.9)
Tax expense	(3.5)		7.2		(2.4)	(5.1)
Nonoperating Income (Expense)	(5.7)		(6.6)		(19.9)	(19.8)
Net income / (loss)	17.8		44.9		47.3	103.7
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income / (loss)	0		(0.8)		0	(1.2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Subsidiaries [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income / (loss)	0.7		1.7		2.1	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		(0.1)		0.1	0
Net income / (loss)	(0.3)		(0.4)		(0.8)	(0.9)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Subsidiaries [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense	0		0		(0.2)	(0.1)
Tax expense	(0.1)		0		(0.1)	0
Net income / (loss)	(0.1)		0		(0.3)	(0.1)
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		(0.1)		(0.1)	(0.1)
Nonoperating Income (Expense)	0.3		0.1		0.9	0.2
Net income / (loss)	0.3		0		0.8	0.1
Amortization of defined benefit pension items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Subsidiaries [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax expense	(0.2)		0.9		(0.6)	(0.5)
Nonoperating Income (Expense)	1		0.8		3	2.6
Net income / (loss)	$ 0.8		$ 1.7		$ 2.4	$ 2.1

Supplemental Financial Inform_5

Supplemental Financial Information (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period		$ (3.6)				$ (3.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0
Other comprehensive income / (loss)	$ 0.1	(0.3)	$ (1)		$ (0.4)	0	$ (2.2)
Balance, end of period	(3.6)					(3.6)
Interest and Debt Expense	(17.1)		(18.3)			(55.4)	(63.7)
Income Tax Expense (Benefit)	10.4		9.1			7.7	11.8
Net income	(8.2)	1.9	35.4		42.1	(2.8)	61.4
Income tax expense / (benefit) from discontinued operations	0.3		(0.2)			0.8	6.3
Nonoperating Income (Expense)	(47.8)		(17.9)			(86.2)	(105.4)
Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period		(36.9)				(36.9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0.1
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(2.1)
Other comprehensive income / (loss)	0.9		1.6	$ (0.9)	$ 0.4	2.2	1.1
Balance, end of period	(34.7)					(34.7)
Interest and Debt Expense	(5.9)		(6.1)			(18.5)	(19.9)
Income Tax Expense (Benefit)	(3.5)		7.2			(2.4)	(5.1)
Net income	17.8		44.9			47.3	103.7
Nonoperating Income (Expense)	(5.7)		(6.6)			(19.9)	(19.8)
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		14.5				14.5
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0.8
Other comprehensive income / (loss)						(0.8)
Balance, end of period	13.7					13.7
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period		(0.4)				(0.4)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0.1
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						0.3
Other comprehensive income / (loss)						(0.2)
Balance, end of period	(0.6)					(0.6)
Change in unfunded pension obligation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period		(18.1)				(18.1)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(0.8)
Other comprehensive income / (loss)						0.8
Balance, end of period	(17.3)					(17.3)
Change in unfunded pension obligation [Member] | Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period		$ (36.5)				(36.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent						(2.4)
Other comprehensive income / (loss)						2.4
Balance, end of period	(34.1)					(34.1)
Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net income	0		(0.8)			0	(1.2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net income	0.7		1.7			2.1	2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Interest and Debt Expense	(0.3)		(0.3)			(0.9)	(0.9)
Income Tax Expense (Benefit)	0		(0.1)			0.1	0
Net income	(0.3)		(0.4)			(0.8)	(0.9)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Interest and Debt Expense	0		0			(0.2)	(0.1)
Income Tax Expense (Benefit)	(0.1)		0			(0.1)	0
Net income	(0.1)		0			(0.3)	(0.1)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Change in unfunded pension obligation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Income Tax Expense (Benefit)	0		(0.1)			(0.1)	(0.1)
Net income	0.3		0			0.8	0.1
Nonoperating Income (Expense)	0.3		0.1			0.9	0.2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Change in unfunded pension obligation [Member] | Subsidiaries [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Income Tax Expense (Benefit)	(0.2)		0.9			(0.6)	(0.5)
Net income	0.8		1.7			2.4	2.1
Nonoperating Income (Expense)	1		0.8			3	2.6
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Income tax expense / (benefit) from discontinued operations	$ 0		$ (0.4)			$ 0	$ (0.4)

Regulatory Matters (Details)

Regulatory Matters (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets, Noncurrent	$ 177		$ 173.8
Unbilled Revenue	15.1		19.4
Due from PJM transmission settlement	1.8		1.8
Recovery of Smart Grid Plan Phase 1 capital investments	249
Aggregate cap of recoverable Smart Grid Plan investments and expenses	267.6
DP&L shareholder funding under Smart Grid Plan	$ 30
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters ESP v. MRO and SEET Proceedings Ohio law requires utilities to file either an ESP or MRO plan to establish SSO rates. From November 1, 2017 through December 18, 2019, DP&L operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (ESP 3). On November 21, 2019, the PUCO issued a supplemental order modifying ESP 3, and as a result DP&L filed a Notice of Withdrawal of its ESP 3 Application and requested to revert to the ESP rates that were in effect prior to ESP 3. The Notice of Withdrawal was approved by the PUCO on December 18, 2019. The PUCO order required, among other things, DP&L to conduct both an ESP v. MRO Test to validate that the ESP is expected to be more favorable in the aggregate than what would be experienced under an MRO, and a prospective SEET, which were filed with the PUCO on April 1, 2020. DP&L is also subject to an annual retrospective SEET. On October 23, 2020, DP&L entered into a Stipulation and Recommendation (settlement) with the staff of the PUCO and various customers, and organizations representing customers of DP&L and certain other parties with respect to, among other matters, DP&L’s applications pending at the PUCO for (i) approval of DP&L’s plan to modernize its distribution grid (the Smart Grid Plan), (ii) findings that DP&L passed the SEET for 2018 and 2019, and (iii) findings that DP&L’s current ESP 1 satisfies the SEET and the more favorable in the aggregate (MFA) regulatory test. The settlement is subject to, and conditioned upon, approval by the PUCO. A hearing has been set for January 11, 2021 for consideration of this settlement. The settlement would provide, among other items, for the following: • Approval of the Smart Grid Plan outlined in the Smart Grid Plan application filed by DP&L with the PUCO, as modified by the terms of the settlement, including, subject to offsetting operational benefits and certain other conditions, a return on and recovery of up to $249.0 million of Smart Grid Plan Phase 1 capital investments and recovery of operational and maintenance expenses through DP&L’s existing Infrastructure Investment Rider for a term of four years, under an aggregate cap of $267.6 million on the amount of such investments and expenses that is recoverable, and an acknowledgement that DP&L may file a subsequent application with the PUCO within three years seeking approvals for Phase 2 of the Smart Grid Plan; • A commitment by DP&L to invest in a customer information system and supporting technologies during Phase 1 of the Smart Grid Plan, with DP&L recovering a return on and of prudently incurred capital investments and operational and maintenance expenses, including deferred operational and maintenance expense amounts, in a future rate case; • A determination that DP&L’s ESP 1 satisfies the prospective SEET and the MFA regulatory test; • A recommendation by parties to the settlement that the PUCO also finds that DP&L satisfies the retrospective SEET for 2018 and 2019; • A commitment by DP&L to file an application with the PUCO no later than October 1, 2023 for a new electric security plan that does not seek to implement certain non-bypassable charges, including those related to provider of last resort risks, stability, or financial integrity; and • DP&L shareholder funding, in an aggregate amount of approximately $30.0 million over four years, for certain economic development discounts, incentives, and grants to certain commercial and industrial customers, including hospitals and manufacturers, assistance for low-income customers as well as the residents and businesses of the City of Dayton, and promotion of solar and resiliency development within DP&L’s service territory. Certain parties which intervened in the ESP proceedings have filed petitions for rehearing of the recent PUCO ESP orders; some of which seek to eliminate DP&L’s RSC from the ESP 1 rates that are currently in place and others seek to re-implement the 2017 ESP, but without the DMR. We are unable to predict the outcomes of these petitions, but if these result in terms that are more adverse than DP&L's current ESP rate plan, it could have a material adverse effect on our results of operations, financial condition and cash flows. The parties signing the above-referenced settlement have agreed to withdraw their respective petitions if the settlement is approved by the PUCO without material modification. Decoupling On January 23, 2020 DP&L filed with the PUCO requesting approval to defer its decoupling costs consistent with the methodology approved in its Distribution Rate Case. If approved, deferral would be effective December 18, 2019 and going forward would reduce impacts of weather, energy efficiency programs and economic changes in customer demand. COVID-19 In response to the PUCO’s COVID-19 emergency orders, DP&L filed an Application on March 23, 2020, requesting waivers of certain rule and tariff requirements and deferral of certain costs and revenues including those related to deposits and reconnection fees, late payment fees, credit card fees; and waived or uncollected amounts associated with putting customers on payment plans. On May 20, 2020, the PUCO approved the application and required DP&L to file a plan outlining the timing and steps it plans to take in an effort to return to normal operations. The authorized deferral of those certain costs and revenues must be offset by COVID-19 related savings. DP&L filed its plan on July 15, 2020 and was approved by the PUCO on August 12, 2020. As a result, DP&L has recorded a $0.8 million regulatory asset as of September 30, 2020. Recovery of these deferrals will be addressed in a future rate proceeding. FERC Proceedings On November 15, 2018 the FERC issued a Notice of Proposed Rulemaking (NOPR) to address amortization of excess accumulated deferred income taxes resulting from the TCJA and their impact on transmission rates. Such notice requires all public utility transmission providers with stated transmission rates under an Open Access Transmission Tariff (OATT) to determine the amount of excess deferred income taxes caused by the TCJA. On March 3, 2020, DP&L filed an application before the FERC to change its transmission rate from a stated rate to a formula rate, which was accepted by the FERC and made effective as of May 3, 2020, subject to further proceeding and potential refunds. The formula rate includes adjustments to flow back over time the excess deferred income taxes caused by the TCJA. The NOPR, therefore, no longer applies to DP&L . The rate changes will increase revenues by approximately $4.1 million through the end of 2020 as of the effective date, subject to refund based on final approved rates.
Subsidiaries [Member]
Regulatory Assets, Noncurrent	$ 177		173.8
Unbilled Revenue	15.1		19.4
Due from PJM transmission settlement	1.8		$ 1.8
Recovery of Smart Grid Plan Phase 1 capital investments	249
Aggregate cap of recoverable Smart Grid Plan investments and expenses	267.6
DP&L shareholder funding under Smart Grid Plan	$ 30
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters ESP v. MRO and SEET Proceedings Ohio law requires utilities to file either an ESP or MRO plan to establish SSO rates. From November 1, 2017 through December 18, 2019, DP&L operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (ESP 3). On November 21, 2019, the PUCO issued a supplemental order modifying ESP 3, and as a result DP&L filed a Notice of Withdrawal of its ESP 3 Application and requested to revert to the ESP rates that were in effect prior to ESP 3. The Notice of Withdrawal was approved by the PUCO on December 18, 2019. The PUCO order required, among other things, DP&L to conduct both an ESP v. MRO Test to validate that the ESP is expected to be more favorable in the aggregate than what would be experienced under an MRO, and a prospective SEET, which were filed with the PUCO on April 1, 2020. DP&L is also subject to an annual retrospective SEET. On October 23, 2020, DP&L entered into a Stipulation and Recommendation (settlement) with the staff of the PUCO and various customers, and organizations representing customers of DP&L and certain other parties with respect to, among other matters, DP&L’s applications pending at the PUCO for (i) approval of DP&L’s plan to modernize its distribution grid (the Smart Grid Plan), (ii) findings that DP&L passed the SEET for 2018 and 2019, and (iii) findings that DP&L’s current ESP 1 satisfies the SEET and the more favorable in the aggregate (MFA) regulatory test. The settlement is subject to, and conditioned upon, approval by the PUCO. A hearing has been set for January 11, 2021 for consideration of this settlement. The settlement would provide, among other items, for the following: • Approval of the Smart Grid Plan outlined in the Smart Grid Plan application filed by DP&L with the PUCO, as modified by the terms of the settlement, including, subject to offsetting operational benefits and certain other conditions, a return on and recovery of up to $249.0 million of Smart Grid Plan Phase 1 capital investments and recovery of operational and maintenance expenses through DP&L’s existing Infrastructure Investment Rider for a term of four years, under an aggregate cap of $267.6 million on the amount of such investments and expenses that is recoverable, and an acknowledgement that DP&L may file a subsequent application with the PUCO within three years seeking approvals for Phase 2 of the Smart Grid Plan; • A commitment by DP&L to invest in a customer information system and supporting technologies during Phase 1 of the Smart Grid Plan, with DP&L recovering a return on and of prudently incurred capital investments and operational and maintenance expenses, including deferred operational and maintenance expense amounts, in a future rate case; • A determination that DP&L’s ESP 1 satisfies the prospective SEET and the MFA regulatory test; • A recommendation by parties to the settlement that the PUCO also finds that DP&L satisfies the retrospective SEET for 2018 and 2019; • A commitment by DP&L to file an application with the PUCO no later than October 1, 2023 for a new electric security plan that does not seek to implement certain non-bypassable charges, including those related to provider of last resort risks, stability, or financial integrity; and • DP&L shareholder funding, in an aggregate amount of approximately $30.0 million over four years, for certain economic development discounts, incentives, and grants to certain commercial and industrial customers, including hospitals and manufacturers, assistance for low-income customers as well as the residents and businesses of the City of Dayton, and promotion of solar and resiliency development within DP&L’s service territory. Certain parties which intervened in the ESP proceedings have filed petitions for rehearing of the recent PUCO ESP orders; some of which seek to eliminate DP&L’s RSC from the ESP 1 rates that are currently in place and others seek to re-implement the 2017 ESP, but without the DMR. We are unable to predict the outcomes of these petitions, but if these result in terms that are more adverse than DP&L's current ESP rate plan, it could have a material adverse effect on our results of operations, financial condition and cash flows. The parties signing the above-referenced settlement have agreed to withdraw their respective petitions if the settlement is approved by the PUCO without material modification. Decoupling On January 23, 2020 DP&L filed with the PUCO requesting approval to defer its decoupling costs consistent with the methodology approved in its Distribution Rate Case. If approved, deferral would be effective December 18, 2019 and going forward would reduce impacts of weather, energy efficiency programs and economic changes in customer demand. COVID-19 In response to the PUCO’s COVID-19 emergency orders, DP&L filed an Application on March 23, 2020, requesting waivers of certain rule and tariff requirements and deferral of certain costs and revenues including those related to deposits and reconnection fees, late payment fees, credit card fees; and waived or uncollected amounts associated with putting customers on payment plans. On May 20, 2020, the PUCO approved the application and required DP&L to file a plan outlining the timing and steps it plans to take in an effort to return to normal operations. The authorized deferral of those certain costs and revenues must be offset by COVID-19 related savings. DP&L filed its plan on July 15, 2020 and was approved by the PUCO on August 12, 2020. As a result, DP&L has recorded a $0.8 million regulatory asset as of September 30, 2020. Recovery of these deferrals will be addressed in a future rate proceeding. FERC Proceedings On November 15, 2018 the FERC issued a Notice of Proposed Rulemaking (NOPR) to address amortization of excess accumulated deferred income taxes resulting from the TCJA and their impact on transmission rates. Such notice requires all public utility transmission providers with stated transmission rates under an Open Access Transmission Tariff (OATT) to determine the amount of excess deferred income taxes caused by the TCJA. On March 3, 2020, DP&L filed an application before the FERC to change its transmission rate from a stated rate to a formula rate, which was accepted by the FERC and made effective as of May 3, 2020, subject to further proceeding and potential refunds. The formula rate includes adjustments to flow back over time the excess deferred income taxes caused by the TCJA. The NOPR, therefore, no longer applies to DP&L . The rate changes will increase revenues by approximately $4.1 million through the end of 2020 as of the effective date, subject to refund based on final approved rates.
COVID-19 Deferral [Member]
Regulatory Assets, Noncurrent	$ 0.8
COVID-19 Deferral [Member] | Subsidiaries [Member]
Regulatory Assets, Noncurrent	$ 0.8
Forecast [Member]
Increase in revenues from proposed transmission rate change to a formula rate		$ 4.1
Forecast [Member] | Subsidiaries [Member]
Increase in revenues from proposed transmission rate change to a formula rate		$ 4.1

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Unrealized Gain (Loss) on Investments	$ 0.3	$ (0.1)	$ 0	$ 0.6
Subsidiaries [Member]
Unrealized Gain (Loss) on Investments	$ 0.3	$ (0.1)	$ 0	$ 0.6

Fair Value (Fair Value and Cost

Fair Value (Fair Value and Cost of Non-Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Long-term Debt	$ 1,393.1	$ 1,363.1
Subsidiaries [Member]
Long-term Debt	574.1	574.4
Cost [Member]
Total Assets	6.3	6.8
Cost [Member] | Subsidiaries [Member]
Total Assets	6.3	6.8
Fair Value [Member]
Total Master Trust Assets, Fair Value	8.2	8.8
Total Assets	8.2	8.8
Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	8.2	8.8
Total Assets	8.2	8.8
Money Market Funds [Member] | Cost [Member]
Total Master Trust Assets, Cost	0.2	0.3
Money Market Funds [Member] | Cost [Member] | Subsidiaries [Member]
Total Master Trust Assets, Cost	0.2	0.3
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Money Market Funds [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Equity Securities [Member] | Cost [Member]
Total Master Trust Assets, Cost	2.1	2.3
Equity Securities [Member] | Cost [Member] | Subsidiaries [Member]
Total Master Trust Assets, Cost	2.1	2.3
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Equity Securities [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Debt Securities [Member] | Cost [Member]
Total Master Trust Assets, Cost	4	4
Debt Securities [Member] | Cost [Member] | Subsidiaries [Member]
Total Master Trust Assets, Cost	4	4
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Debt Securities [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Hedge Funds [Member] | Cost [Member]
Total Master Trust Assets, Cost	0	0.1
Hedge Funds [Member] | Cost [Member] | Subsidiaries [Member]
Total Master Trust Assets, Cost	0	0.1
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0	0.1
Hedge Funds [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Cost [Member]
Total Master Trust Assets, Cost	0	0.1
Tangible Assets [Member] | Cost [Member] | Subsidiaries [Member]
Total Master Trust Assets, Cost	0	0.1
Tangible Assets [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Debt [Member] | Cost [Member]
Long-term Debt	1,393.1	1,363.1
Debt [Member] | Cost [Member] | Subsidiaries [Member]
Long-term Debt	574.1	574.4
Debt [Member] | Fair Value [Member]
Debt, Fair Value	1,499.4	1,404
Debt [Member] | Fair Value [Member] | Subsidiaries [Member]
Debt, Fair Value	$ 615.2	$ 600.5

Fair Value (Fair Value of Asset

Fair Value (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Level 1 [Member]
Total Master Trust Assets, Fair Value	$ 0.2	$ 0.3
Total Derivative Assets	0	0
Total Assets	0.2	0.3
Total Liabilities	0	0
Level 1 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Total Derivative Assets	0	0
Total Assets	0.2	0.3
Total Liabilities	0	0
Level 1 [Member] | Subsidiaries [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 2 [Member]
Total Master Trust Assets, Fair Value	8	8.5
Total Derivative Assets	0	0.1
Total Assets	8	8.6
Total Liabilities	1,482	1,386.5
Level 2 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0.1
Level 2 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	8	8.5
Total Derivative Assets	0	0.1
Total Assets	8	8.6
Total Liabilities	597.8	583
Level 2 [Member] | Subsidiaries [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0.1
Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Total Derivative Assets	0	0
Total Assets	0	0
Total Liabilities	17.4	17.5
Level 3 [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Level 3 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Total Derivative Assets	0	0
Total Assets	0	0
Total Liabilities	17.4	17.5
Level 3 [Member] | Subsidiaries [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0
Fair Value [Member]
Total Master Trust Assets, Fair Value	8.2	8.8
Total Derivative Assets	0	0.1
Total Assets	8.2	8.9
Total Liabilities	1,499.4	1,404
Fair Value [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0.1
Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	8.2	8.8
Total Derivative Assets	0	0.1
Total Assets	8.2	8.9
Total Liabilities	615.2	600.5
Fair Value [Member] | Subsidiaries [Member] | Interest Rate Contract [Member]
Total Derivative Assets	0	0.1
Money Market Funds [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Money Market Funds [Member] | Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Money Market Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Level 2 [Member] | Subsidiaries [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] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Money Market Funds [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0.2	0.3
Equity Securities [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Equity Securities [Member] | Level 2 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Equity Securities [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Level 3 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Equity Securities [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	3.9	4.2
Debt Securities [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Debt Securities [Member] | Level 2 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Debt Securities [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Level 3 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Debt Securities [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	4.1	4.1
Hedge Funds [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0	0.1
Hedge Funds [Member] | Level 2 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Hedge Funds [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Level 3 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0	0.1
Hedge Funds [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 1 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Level 2 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Level 3 [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Level 3 [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0
Tangible Assets [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0	0.1
Tangible Assets [Member] | Fair Value [Member] | Subsidiaries [Member]
Total Master Trust Assets, Fair Value	0	0.1
Debt [Member] | Level 1 [Member]
Debt	0	0
Debt [Member] | Level 1 [Member] | Subsidiaries [Member]
Debt	0	0
Debt [Member] | Level 2 [Member]
Debt	1,482	1,386.5
Debt [Member] | Level 2 [Member] | Subsidiaries [Member]
Debt	597.8	583
Debt [Member] | Level 3 [Member]
Debt	17.4	17.5
Debt [Member] | Level 3 [Member] | Subsidiaries [Member]
Debt	17.4	17.5
Debt [Member] | Fair Value [Member]
Debt	1,499.4	1,404
Debt [Member] | Fair Value [Member] | Subsidiaries [Member]
Debt	$ 615.2	$ 600.5

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Millions	Sep. 30, 2020USD ($)Number_of_interest_rate_swaps
Subsidiaries [Member]
Debt Instrument, Number of Financial Covenants | Number_of_interest_rate_swaps	2
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] | Subsidiaries [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] | Subsidiaries [Member]
Derivative, Notional Amount, Purchase (Sales), Net	$ 140

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities (Outstanding Derivative Instruments) (Details) - Designated as Hedging Instrument [Member] - Interest Rate Swap [Member] $ in Millions	Sep. 30, 2020USD ($)
Derivative, Notional Amount, Purchase (Sales), Net	$ 140
Subsidiaries [Member]
Derivative, Notional Amount, Purchase (Sales), Net	$ 140

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	$ 13.9	$ 15.3	$ 14.5	$ 16.6
Net gains / (losses) associated with current period hedging transactions	0.1	(0.2)	0	(1)
Ending accumulated derivative gain / (loss) in AOCI	13.7	14.7	13.7	14.7
Portion expected to be reclassified to earnings in the next twelve months	(0.1)		$ (0.1)
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			0 months
Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI		0.4		0.4
Net gains / (losses) associated with current period hedging transactions		0		0
Ending accumulated derivative gain / (loss) in AOCI		0		0
Subsidiaries [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	(0.7)	(0.3)	$ (0.4)	0.6
Net gains / (losses) associated with current period hedging transactions	0.2	(0.1)	0.1	(0.9)
Ending accumulated derivative gain / (loss) in AOCI	(0.6)	(0.4)	(0.6)	(0.4)
Portion expected to be reclassified to earnings in the next twelve months	0.6		$ 0.6
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			0 months
Interest Expense [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.3)	(0.4)	$ (0.8)	(0.9)
Interest Expense [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings		0		0
Interest Expense [Member] | Subsidiaries [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.1)	0	(0.3)	(0.1)
Discontinued Operations, Held-for-sale or Disposed of by Sale | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	$ 0	0	$ 0	0
Discontinued Operations, Held-for-sale or Disposed of by Sale | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings		$ (0.4)		$ (0.4)

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities (Fair Value and Balance Sheet Location (Details) - Designated as Hedging Instrument [Member] - Interest Rate Swap [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative, Notional Amount, Purchase (Sales), Net	$ 140
Subsidiaries [Member]
Derivative, Notional Amount, Purchase (Sales), Net	140
Other Current Assets [Member]
Derivative Asset, Fair Value	0	$ 0.1
Other Current Assets [Member] | Subsidiaries [Member]
Derivative Asset, Fair Value	$ 0	$ 0.1

Debt (Narrative) (Details)

Debt (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)fiscal_quarterdebt_covenant	Sep. 30, 2019USD ($)	Dec. 31, 2022USD ($)	Sep. 30, 2022USD ($)	Aug. 03, 2020USD ($)	Jun. 01, 2020USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 110
Long-term Line of Credit	90						$ 104
Retirement of long-term debt	$ 550.8	$ 978
Debt Covenant, Leverage Ratio, Maximum	0.67
Debt Covenant, Interest Coverage Ratio, Minimum	1.70					2.25
Interest Coverage Ratio	2.72
Line of Credit Facility, Current Borrowing Capacity						$ 125
Proceeds from Issuance of Long-term Debt	$ 555	821.7
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum	$ 125
Debt Instrument, Debt Covenant, Total Debt to EBITDA Ratio	7
Line of Credit Facility, quarterly borrowing limit reduction	$ 5
Phase 1 [Member]
Debt Instrument [Line Items]
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum	130
Phase 2 [Member]
Debt Instrument [Line Items]
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum	150
Forecast [Member]
Debt Instrument [Line Items]
Debt Covenant, Interest Coverage Ratio, Minimum			2	1.75
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum			$ 150	$ 130
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	0						40
Retirement of long-term debt	140	436.1
Proceeds from Issuance of Long-term Debt	140	$ 422.3
3.95% Senior Notes due 2049 [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 425						$ 425
Debt Instrument, Interest Rate, Effective Percentage	3.95%
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage							2.47%
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140				$ 140		$ 140
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
Debt Covenant, Interest Coverage Ratio, Minimum	2.50
Ten Year Senior Unsecured Notes At725 Maturing At October152021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross							$ 380
Debt instrument interest percentage	7.25%
Make Whole Premium	$ 30.8
Revolving Credit Facility [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum	0.67
Total Debt to Total Capitalization Ratio	0.48
4.125% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.125%
Proceeds from Issuance of Long-term Debt	$ 415
3.25% First Mortgage Bonds due 2040 [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	140
Proceeds from Issuance of Long-term Debt	$ 140
Debt Instrument, Interest Rate, Effective Percentage	3.20%
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	2.93%						2.47%
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140

Debt (Long-term Debt) (Details)

Debt (Long-term Debt) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2022USD ($)	Sep. 30, 2022USD ($)	Aug. 03, 2020USD ($)	Jun. 01, 2020	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Unamortized deferred finance costs	$ (10.6)						$ (5.9)
Unamortized debt discounts and premiums, net	(1)						(1)
Total long-term debt	1,393.1						1,363.1
Less: current portion	(0.2)						(139.8)
Long-term debt	1,392.9						1,223.3
Long-term Line of Credit	$ 90						104
Debt Covenant, Interest Coverage Ratio, Minimum	1.70					2.25
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum	$ 125
Proceeds from Issuance of Long-term Debt	$ 555	$ 821.7
Long-term Debt	Long-term Debt The following table summarizes DPL's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95% 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20% 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20% 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt at DP&L 574.1 574.4 Senior unsecured bonds 7.25% 2021 — 380.0 Senior unsecured bonds 4.125% 2025 415.0 — Senior unsecured bonds 4.35% 2029 400.0 400.0 Note to DPL Capital Trust II (c) 8.125% 2031 15.6 15.6 Unamortized deferred financing costs (10.6) (5.9) Unamortized debt discounts and premiums, net (1.0) (1.0) Total long-term debt 1,393.1 1,363.1 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 1,392.9 $ 1,223.3 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. (c) Note payable to related party. Lines of credit At September 30, 2020 and December 31, 2019, DPL had outstanding borrowings on its line of credit of $90.0 million and $104.0 million, respectively. At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Consolidated Balance Sheet. On June 19, 2020 DPL closed a $415.0 million issuance of senior unsecured notes. These notes carry an interest rate of 4.125% and mature on July 1, 2025. Proceeds from the issuance and cash on hand were used to redeem in-full the remaining balance of $380.0 million of DPL's 7.25% senior unsecured notes. These bonds were redeemed at par plus accrued interest and a make-whole premium of $30.8 million on July 20, 2020. On June 1, 2020 DPL amended its secured revolving credit facility. As a result of the amendment, the borrowing limit was reduced from $125.0 million to $110.0 million, the Total Debt to EBITDA covenant was eliminated, the EBITDA to Interest Expense covenant was reduced from 2.25 to 1.00 to 1.70 to 1.00, increasing to 1.75 to 1.00 as of September 30, 2022 and 2.00 to 1.00 as of December 31, 2022, and a trailing-twelve months minimum EBITDA covenant of $125.0 million was added, increasing to $130.0 million as of September 30, 2022 and $150.0 million as of December 31, 2022. Starting with the quarter ended September 30, 2021, the borrowing limit will be reduced by $5.0 million per quarter should DPL’s Total Debt to EBITDA ratio calculated for the period of four consecutive quarters exceed 7.00 to 1.00. Long-term debt covenants and restrictions DPL’s revolving credit agreement has two financial covenants. The first financial covenant, a minimum EBITDA, calculated at the end of each fiscal quarter for the four prior fiscal quarters, of $125.0 million is required, stepping up to $130.0 million on September 30, 2022 and $150.0 million on December 31, 2022. As of September 30, 2020, this financial covenant was in compliance. 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 1.70 to 1.00, and steps up to 1.75 to 1.00 on September 30, 2022 and 2.00 to 1.00 as of December 31, 2022. As of September 30, 2020, this financial covenant was met with a ratio of 2.72 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. As a result, as of September 30, 2020, DPL was prohibited from making a distribution to its shareholder or making a loan to any of its affiliates (other than its subsidiaries). DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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.
Forecast [Member]
Debt Instrument [Line Items]
Debt Covenant, Interest Coverage Ratio, Minimum			2	1.75
Debt Instrument, Debt Covenant, EBITDA to Interest Expense, EBITDA Minimum			$ 150	$ 130
Subsidiaries [Member]
Debt Instrument [Line Items]
Unamortized deferred finance costs	$ (5.7)						(5.4)
Unamortized debt discounts and premiums, net	(2.6)						(2.7)
Total long-term debt at subsidiary	574.1						574.4
Total long-term debt	574.1						574.4
Less: current portion	(0.2)						(139.8)
Long-term debt	573.9						434.6
Long-term Line of Credit	0						40
Proceeds from Issuance of Long-term Debt	$ 140	$ 422.3
Long-term Debt	Long-term Debt The following table summarizes DP&L's long-term debt. Interest September 30, December 31, $ in millions Rate Maturity 2020 2019 First Mortgage Bonds 3.95 % 2049 $ 425.0 $ 425.0 First Mortgage Bonds 3.20 % 2040 140.0 — Tax-exempt First Mortgage Bonds - rates from 2.40% - 2.93% (a) and 1.15% - 2.47% (b) 2020 — 140.0 U.S. Government note 4.20 % 2061 17.4 17.5 Unamortized deferred financing costs (5.7) (5.4) Unamortized debt discounts and premiums, net (2.6) (2.7) Total long-term debt 574.1 574.4 Less: current portion (0.2) (139.8) Long-term debt, net of current portion $ 573.9 $ 434.6 (a) Range of interest rates for the nine months ended September 30, 2020. (b) Range of interest rates for the year ended December 31, 2019. Line of credit At September 30, 2020 and December 31, 2019, DP&L had outstanding borrowings on its line of credit of $0.0 million and $40.0 million, respectively. Significant transactions On July 31, 2020, DP&L issued $140.0 million of taxable First Mortgage Bonds and on August 3, 2020 used the proceeds to purchase at par value the $140.0 million of outstanding tax-exempt Ohio Air Quality Development Authority (OAQDA) Collateralized Pollution Control Revenue Refunding Bonds that had been issued in 2015. The new taxable First Mortgage Bonds carry an interest rate of 3.20% and mature on July 31, 2040. The OAQDA Revenue bonds have not been legally cancelled and can be re-issued at the discretion of DP&L at any time. These bonds will be held in trust while we continue to evaluate market conditions and explore suitable long-term financing alternatives. Accordingly, at September 30, 2020, the $140.0 million variable rate OAQDA Revenue bonds are not treated as being outstanding in the Condensed Balance Sheet for DP&L. Long-term debt covenants and restrictions DP&L's unsecured revolving credit facility and Bond Purchase Agreement (financing document entered into in connection with the issuance of DP&L's First Mortgage Bonds, on July 31, 2020) 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 0.48 to 1.00 as of September 30, 2020. As of September 30, 2020, 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.
3.95% Senior Notes due 2049 [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.95%
Long-term Debt, Gross	$ 425						425
DPL Revolving Credit Agreement and Term Loan Maturing July 2020 [Member]
Debt Instrument [Line Items]
Debt Covenant, Interest Coverage Ratio, Minimum	2.50
Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140				$ 140		140
U.S. Government note maturing in February 2061 - 4.20% [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.20%
Long-term Debt, Gross	$ 17.4						17.5
Senior unsecured due in October 2021 - 7.25% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	7.25%
Extinguishment of Debt, Amount	$ 380
Long-term Debt, Gross							380
4.35% Senior Notes due 2029 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.35%
Long-term Debt, Gross	$ 400						400
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
4.13% Senior Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest percentage	4.125%
Long-term Debt, Gross	$ 415
4.125% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.125%
Proceeds from Issuance of Long-term Debt	$ 415
3.25% First Mortgage Bonds due 2040 [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.20%
Proceeds from Issuance of Long-term Debt	$ 140
Long-term Debt, Gross	140
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	140
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 140
Maximum [Member] | Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage							2.47%
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	2.93%
Maximum [Member] | One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	2.93%						2.47%
Minimum [Member] | Pollution Control Series Maturing in August 2020 - 1.13% - 1.14% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage							1.15%
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	2.40%
Minimum [Member] | One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	2.40%						1.15%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Entity Information [Line Items]
Effective Income Tax Rate Reconciliation, at Combined Federal and State Statutory Income Tax Rate, Percent						22.30%
Estimated annual effective income tax rate							(10.10%)
Effective Income Tax Rate Reconciliation, Including Discontinued Operations, Percent	55.20%		(35.60%)			71.10%	(9.80%)
Non-cash capital contribution	$ 0.1	$ 98	$ 2.7	$ (1.5)	$ 1.5	$ 0	$ 2.7
Payment against tax receivable balance from Parent						$ (52)
Subsidiaries [Member]
Entity Information [Line Items]
Effective income tax rates			(19.10%)				4.70%
Effective Income Tax Rate Reconciliation, at Combined Federal and State Statutory Income Tax Rate, Percent						22.30%
Effective Income Tax Rate Reconciliation, Including Discontinued Operations, Percent	16.40%					4.80%	4.50%

Benefit Plans (Net Periodic Ben

Benefit Plans (Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Contributions by employer			$ 7.5	$ 7.5
Pension [Member]
Service cost	$ 0.9	$ 0.9	2.8	2.7
Interest cost	2.9	3.7	8.8	11.2
Expected return on assets	(4.6)	(5)	(14)	(15)
Prior service cost	0.3	0.3	0.8	0.9
Actuarial loss / (gain)	1.5	1.1	4.6	3.2
Net periodic benefit cost	1	1	3	3
Postretirement [Member]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	9.1		9.1		$ 9.6
Subsidiaries [Member] | Pension [Member]
Contributions by employer			7.5	7.5
Service cost	0.9	0.9	2.8	2.7
Interest cost	2.9	3.7	8.8	11.2
Expected return on assets	(4.6)	(5)	(14)	(15)
Prior service cost	0.3	0.4	1	1.3
Actuarial loss / (gain)	2.2	1.8	6.5	5.3
Net periodic benefit cost	1.7	$ 1.8	5.1	$ 5.5
Subsidiaries [Member] | Postretirement [Member]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 9.1		$ 9.1		$ 9.6

Shareholder's Equity (Details)

Shareholder's Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Stockholders' Equity Note Disclosure									Shareholder's Deficit Capital Contributions from AES In DP&L's six-year 2017 ESP, the PUCO imposed restrictions on DPL making dividend payments to its parent company, AES, during the term of the ESP, as well as on making tax-sharing payments to AES during the term of the DMR. The PUCO also required 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 . With the November 21, 2019 order from the PUCO that removed the DMR and the subsequent approval of DP&L's ESP 1 rate plan, these requirements were eliminated. See Note 3 – Regulatory Matters in Item 8. — Financial Statements and Supplementary Data of our Form 10-K for additional information on changes to DP&L's ESP and the removal of the DMR. For the nine months ended September 30, 2019, AES made a capital contribution of $2.7 million by converting the amount owed to it by DPL related to tax-sharing payments for current tax liabilities. During the nine months ended September 30, 2020, DPL received $150.0 million in a cash contribution from AES, which DPL then used to make a $150.0 million capital contribution to DP&L . The contribution at DPL represented an equity capital contribution of $98.0 million and a payment of $52.0 million against its tax receivable. The proceeds from the capital contribution at DP&L will primarily be used for funding needs to support DP&L's capital expenditure program, mainly new investments in and upgrades to DP&L’s transmission and distribution system.
Non-cash capital contribution	$ 0.1	$ 98	$ 2.7		$ (1.5)		$ 1.5		$ 0	$ 2.7
Common Stock, Shares Authorized	1,500		1,500						1,500	1,500	1,500
Par value common shares (in USD per share)	$ 0.01								$ 0.01
Proceeds from Contributions from Parent									$ 98	$ 0
Cash Contribution from Parent Company									150
Income Taxes Paid, Net									$ (51.9)	$ 1.3
Other Additional Capital [Member]
Class of Stock [Line Items]
Non-cash capital contribution	$ 0.1		$ 2.7	[1]	(1.5)	[1]	$ 1.5	[1]
Proceeds from Contributions from Parent		98
Subsidiaries [Member]
Class of Stock [Line Items]
Stockholders' Equity Note Disclosure									Shareholder's Equity Capital Contribution and Returns of Capital During the nine months ended September 30, 2020, DPL made a capital contribution of $150.0 million to DP&L. The proceeds will primarily be used for funding needs to support DP&L 's capital expenditure program, mainly new investments in and upgrades to DP&L’s transmission and distribution system. Additionally, DP&L declared return of capital payments of $42.7 million to DPL, of which $27.7 million was paid during the period. During the nine months ended September 30, 2019, DP&L made returns of capital payments of $90.0 million to DPL .
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
Common Stock, Shares, Outstanding	41,172,173								41,172,173		41,172,173
Proceeds from Contributions from Parent		150							$ 150	$ 0
Dividends, Common Stock, Cash	$ (28.5)	(14.2)	$ (20)		(70)
Subsidiaries [Member] | Other Additional Capital [Member]
Class of Stock [Line Items]
Dividends, Common Stock, Cash	$ (28.5)	$ (14.2)	$ (20)		$ (70)				(27.7)	$ (90)
Dividends, Common Stock									$ (42.7)
[1]	Represents the conversion of a tax sharing payable to AES to contributed capital, as DP&L's

Contractual Obligations, Comm_2

Contractual Obligations, Commercial Commitments and Contingencies (Narrative) (Details) $ in Millions	Sep. 30, 2020USD ($)
AES Ohio Generation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	$ 1.9
Debt Obligation on 4.9% Equity Ownership [Member] | Subsidiaries [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Equity ownership interest	4.90%
Equity ownership interest aggregate cost	$ 63.4
Electric Generation Company [Member] | Subsidiaries [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Debt obligation	$ 1,294.3

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)mi²customersegment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Total assets	$ 1,907.5		$ 1,907.5		$ 1,935.8
Gain (Loss) on Extinguishment of Debt	(31.7)	$ 0	(31.7)	$ (44.9)
Subsidiaries [Member]
Segment Reporting Information [Line Items]
Total assets	1,890.5		$ 1,890.5		1,883.2
Number of Operating Segments | segment			1
Approximate number of retail customers | customer			530,000
Service area, square miles | mi²			6,000
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
Total assets	1,890.5		$ 1,890.5		1,883.2
Gain (Loss) on Extinguishment of Debt	0		0	0
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total assets	17		17		$ 52.6
Gain (Loss) on Extinguishment of Debt	$ (31.7)		$ (31.7)	$ (44.9)

Business Segments (Segment Fina

Business Segments (Segment Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
External customer revenues	$ 178.8		$ 192.9		$ 505.1	$ 576.5
Intersegment revenues	0		0		0	0
Total revenues	178.8		192.9		505.1	576.5
Depreciation and amortization	18.6		17.7		54.8	54
Fuel Costs	0.4		0.6		1.3	2
Depreciation and amortization					55.1	34.2
Interest expense	17.1		18.3		55.4	63.7
Gain (Loss) on Extinguishment of Debt	31.7		0		31.7	44.9
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(19.7)		27.1		(13.6)	25.7
Net income / (loss) from continuing operations	(9.3)		36.2		(5.9)	37.5
Discontinued operations, net of tax	1.1		(0.8)		3.1	23.9
Net income/ (loss)	(8.2)	$ 1.9	35.4	$ 42.1	(2.8)	61.4
Capital expenditures	44.7		59		128.7	122.4
Total assets	1,907.5				1,907.5		$ 1,935.8
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
External customer revenues	176.8		190.9		498.4	569.4
Intersegment revenues	0.2		0.2		0.7	0.8
Total revenues	177		191.1		499.1	570.2
Depreciation and amortization	18.2		17.4		53.7	52.9
Interest expense	5.9		6.1		18.5	19.9
Gain (Loss) on Extinguishment of Debt	0				0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	21.3		37.7		49.7	108.8
Capital expenditures	44.6		58.9		125.1	121.1
Total assets	1,890.5				1,890.5		1,883.2
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
External customer revenues	2		2		6.7	7.1
Intersegment revenues	1		0.8		2.7	2.4
Total revenues	3		2.8		9.4	9.5
Depreciation and amortization	0.4		0.3		1.1	1.1
Interest expense	11.2		12.2		36.9	43.8
Gain (Loss) on Extinguishment of Debt	31.7				31.7	44.9
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(41)		(10.6)		(63.3)	(83.1)
Capital expenditures	0.1		0.1		3.6	1.3
Total assets	17				17		52.6
Adjustments and Eliminations [Member]
Segment Reporting Information [Line Items]
External customer revenues	0		0		0	0
Intersegment revenues	(1.2)		(1)		(3.4)	(3.2)
Total revenues	(1.2)		(1)		(3.4)	(3.2)
Depreciation and amortization	0		0		0	0
Interest expense	0		0		0	0
Gain (Loss) on Extinguishment of Debt	0				0	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]
Depreciation and amortization	18.2		17.4		53.7	52.9
Fuel Costs	0.4		0.6		1.3	2
Depreciation and amortization					53.7	52.9
Interest expense	5.9		6.1		18.5	19.9
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	21.3		37.7		49.7	108.8
Net income/ (loss)	17.8		$ 44.9		47.3	$ 103.7
Total assets	$ 1,890.5				$ 1,890.5		$ 1,883.2

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer, Excluding Assessed Tax	$ 177	$ 188.9	$ 492.3	$ 560.8
RTO Revenue	11.4	11.1	32.3	32.9
RTO Capacity Revenue	0.9	1.1	3.2	5
Revenues	178.8	192.9	505.1	576.5
Contract with Customer, Asset, before Allowance for Credit Loss	67.3		67.3		$ 65.1
Corporate, Non-Segment [Member]
RTO Revenue	(0.1)	0.1	0	0.1
RTO Capacity Revenue	0	0	0	0
Revenues	3	2.8	9.4	9.5
Adjustments and Eliminations [Member]
RTO Revenue	0	0	0	0
RTO Capacity Revenue	0	0	0	0
Revenues	(1.2)	(1)	(3.4)	(3.2)
Utility [Member]
RTO Revenue	11.5	11	32.3	32.8
RTO Capacity Revenue	0.9	1.1	3.2	5
Revenues	177	191.1	499.1	570.2
Subsidiaries [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	175.2	187	486.3	554.4
RTO Revenue	11.5	11	32.3	32.8
RTO Capacity Revenue	0.9	1.1	3.2	5
Revenues	177	191.1	499.1	570.2
Contract with Customer, Asset, before Allowance for Credit Loss	66.3		66.3		$ 64.4
Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2.1	2	6.7	7.1
Other non-606 revenue	1.7	0.2	4	0.8
Other Revenues [Member] | Corporate, Non-Segment [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2.1	2	6.7	7.1
Other non-606 revenue	1	0.7	2.7	2.3
Other Revenues [Member] | Adjustments and Eliminations [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Other non-606 revenue	(1)	(0.8)	(2.7)	(2.4)
Other Revenues [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Other non-606 revenue	1.7	0.3	4	0.9
Other Revenues [Member] | Subsidiaries [Member]
Other non-606 revenue	1.7	0.3	4	0.9
Wholesale Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3	4.2	7	12
Wholesale Revenue [Member] | Corporate, Non-Segment [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Wholesale Revenue [Member] | Adjustments and Eliminations [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.2)	(0.2)	(0.7)	(0.8)
Wholesale Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.2	4.4	7.7	12.8
Wholesale Revenue [Member] | Subsidiaries [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.2	4.4	7.7	12.8
Retail Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	159.6	170.5	443.1	503.8
Other non-606 revenue	0.1	3.8	8.8	14.9
Retail Revenue [Member] | Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	99.3	107.5	279.9	313.9
Retail Revenue [Member] | Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	32.2	34.8	87.6	103.7
Retail Revenue [Member] | Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	14.5	13.7	38.2	43.5
Retail Revenue [Member] | Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	9.9	11.4	27.7	33.3
Retail Revenue [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.7	3.1	9.7	9.4
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] | Corporate, Non-Segment [Member] | Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Corporate, Non-Segment [Member] | Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Corporate, Non-Segment [Member] | Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Corporate, Non-Segment [Member] | Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Corporate, Non-Segment [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [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] | Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [Member] | Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [Member] | Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [Member] | Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Adjustments and Eliminations [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	159.6	170.5	443.1	503.8
Other non-606 revenue	0.1	3.8	8.8	14.9
Retail Revenue [Member] | Utility [Member] | Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	99.3	107.5	279.9	313.9
Retail Revenue [Member] | Utility [Member] | Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	32.2	34.8	87.6	103.7
Retail Revenue [Member] | Utility [Member] | Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	14.5	13.7	38.2	43.5
Retail Revenue [Member] | Utility [Member] | Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	9.9	11.4	27.7	33.3
Retail Revenue [Member] | Utility [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 3.7	$ 3.1	$ 9.7	$ 9.4

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
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	$ 4.5	$ 0.1
Disposal Group, Including Discontinued Operation, Revenue	0.9	16.2	23.3	56.7
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net					$ 18
Disposal Group, Including Discontinued Operation, Other Assets, Current					0.3
Disposal Group, Including Discontinued Operation, Assets					23.4
Disposal Group, Including Discontinued Operation, Accounts Payable					5.6
Disposal Group, Including Discontinued Operation, Other Liabilities, Current					3.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent					6.3
Disposal Group, Including Discontinued Operation, Liabilities					17.4
Disposal Group, Including Discontinued Operation, Operating and Other Expenses	0.5	(17.2)	(23.9)	(26.6)
Disposal Group, Including Discontinued Operation, Asset Retirement Obligation, Revision of Estimate				22.5
Cash Provided by (Used in) Operating Activities, Discontinued Operations	1.5	(1.7)	5.1	9.9
Disposal Group, Including Discontinued Operation, Inventory					3.7
Disposal Group, Including Discontinued Operation, Intangible Assets					0.1
Disposal Group, Including Discontinued Operation, Deferred Tax Assets					6.5
Disposal Group, Including Discontinued Operation, Accrued Income Tax Payable					0.3
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent					1
Disposal Group, Including Discontinued Operations, Asset Retirement Obligation					8.3
Disposal Group, Including Discontinued Operation, Accrued Property Taxes					0.3
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(19.7)	27.1	(13.6)	25.7
Property, Plant and Equipment, Additions	44.7	59	128.7	122.4
Payments for Removal Costs			1	0
Disposal GroupDisposal Group, Including Discontinued Operations, Taxes Applicable to Subsequent Years					$ 0.3
Loss from discontinued operations before income taxes	1.4	(1)	(0.6)	30.1
Income tax expense / (benefit) from discontinued operations	0.3	(0.2)	0.8	6.3
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1.1	(0.8)	3.1	23.9
Cash Provided by (Used in) Operating Activities, Discontinued Operations	1.5	(1.7)	5.1	9.9
Cash flows from investing activities for discontinued operations	(0.4)		4
Subsidiaries [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	$ 21.3	$ 37.7	49.7	$ 108.8
Conesville [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			4.5
Payments for Removal Costs			1
Conesville [Member] | Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for Removal Costs			$ 4

Risk & Uncertainties (Details)

Risk & Uncertainties (Details)	3 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2020
Unusual Risk or Uncertainty [Line Items]
Unusual Risks and Uncertainties			As the economic impact of the COVID-19 pandemic started to materialize in Ohio in the second half of March and continued in the second and third quarters of 2020, the COVID-19 pandemic primarily impacted our retail sales demand as shown by the changes in weather-normalized volumes of kWh sold: Customer class For the three months ended September 30, 2020 compared to the same period in 2019 For the six months ended September 30, 2020 compared to the same period in 2019 (a) For the nine months ended September 30, 2020 compared to the same period in 2019 Commercial (4.8)% (9.4)% (7.0)% Industrial 0.9% (9.3)% (6.8)% Residential 11.0% 9.8% 6.0% (a) This period most closely approximates the duration of the economic impact on our sales demand as a result of the COVID-19 pandemic.
Residential [Member]
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	11.00%	9.80%	6.00%
Commercial
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	(4.80%)	(9.40%)	(7.00%)
Industrial
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	0.90%	(9.30%)	(6.80%)
Subsidiaries [Member]
Unusual Risk or Uncertainty [Line Items]
Unusual Risks and Uncertainties			COVID-19 Pandemic The COVID-19 pandemic has severely impacted global economic activity, including electricity and energy consumption, and caused significant volatility and negative pressure in financial markets. The global impact of the outbreak has been rapidly evolving and many countries, including the United States, have reacted by instituting quarantines, mandating business and school closures and social distancing measures as well as restricting travel. The State of Ohio has implemented, among other things, stay-at-home and other social distancing measures to slow the spread of the virus, which has impacted energy demand within our service territory, though the stay-at-home restrictions have now been lifted in our service territory. On March 12, 2020, the PUCO also issued an emergency order prohibiting electric utilities, including us, from discontinuing electric utility service to customers. This prohibition ended for DP&L on September 1, 2020. We are taking a variety of measures in response to the spread of COVID-19 to ensure our ability to transmit, distribute and sell electric energy, ensure the health and safety of our employees, contractors, customers and communities and provide essential services to the communities in which we operate. In addition to the impacts to demand within our service territory, we also have incurred and expect to continue to incur expenses relating to COVID-19, and such expenses may include those that relate to events outside of our control. As the economic impact of the COVID-19 pandemic started to materialize in Ohio in the second half of March and continued in the second and third quarters of 2020, the COVID-19 pandemic primarily impacted our retail sales demand as shown by the changes in weather-normalized volumes of kWh sold: Customer class For the three months ended September 30, 2020 compared to the same period in 2019 For the six months ended September 30, 2020 compared to the same period in 2019 (a) For the nine months ended September 30, 2020 compared to the same period in 2019 Commercial (4.8)% (9.4)% (7.0)% Industrial 0.9% (9.3)% (6.8)% Residential 11.0% 9.8% 6.0% (a) This period most closely approximates the duration of the economic impact on our sales demand as a result of the COVID-19 pandemic.
Subsidiaries [Member] | Residential [Member]
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	11.00%	9.80%	6.00%
Subsidiaries [Member] | Commercial
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	(4.80%)	(9.40%)	(7.00%)
Subsidiaries [Member] | Industrial
Unusual Risk or Uncertainty [Line Items]
Percentage Increase/Decrease in weather-normalized volumes of kWh sold	0.90%	(9.30%)	(6.80%)