Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum

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Disposal Group, Including Discontinued Operations, Long-Term Debt

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Letter Of Credit Sublimit

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Line of Credit Facility, Additional Borrowing Capacity

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Long Term Debt Maturities Repayments Of Principal, Total

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Make Whole Premium

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Total Debt to Total Capitalization Ratio

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Total Maturities Before Unamortized Adjustments

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Unamortized Deferred Financing Costs

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Unamortized Deferred Financing Costs, Consolidated

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Unamortized Deferred Financing Costs (Subsidiary)

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount.

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Gross amount of debt extinguished.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of long-term debt and capital lease obligations including current maturities.

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No definition available.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Debt (Long-term Debt Maturities) (Details) $ in Millions		12 Months Ended
Debt (Long-term Debt Maturities) (Details) $ in Millions	Jun. 06, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	May 07, 2019 USD ($)	Apr. 30, 2018 USD ($)	Mar. 30, 2018 USD ($)	Oct. 01, 2017 USD ($)
Debt Instrument [Line Items]
Total Debt to Total Capitalization Ratio		0.57
Long-term Line of Credit		$ 104.0	$ 0.0
Line of Credit Facility, Maximum Borrowing Capacity		125.0
Proceeds from Issuance of Long-term Debt		$ 821.7	0.0	$ 0.0
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum		0.65
Unamortized Deferred Financing Costs, Consolidated		$ (11.3)
Current portion - long-term debt		140.2
Long-term Debt, Maturities, Repayments of Principal in Year Two		380.2
2018		0.2
2019		0.2
2020		0.2
Thereafter		857.1
Total Maturities		1,378.1
Total long-term debt		1,363.1
Unamortized Deferred Financing Costs		(5.9)	(4.3)
Current portion - long-term debt		139.8	103.6
Long-term Debt, Excluding Current Maturities		1,223.3	1,372.3
Letter Of Credit Sublimit		75.0
Line of Credit Facility, Additional Borrowing Capacity		50.0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		40.0	0.0
Line of Credit Facility, Maximum Borrowing Capacity		175.0
Proceeds from Issuance of Long-term Debt		$ 422.3	0.0	$ 0.0
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum		0.65
Unamortized Deferred Financing Costs, Consolidated		$ (5.4)
Current portion - long-term debt		140.2
Long-term Debt, Maturities, Repayments of Principal in Year Two		0.2
2018		0.2
2019		0.2
2020		0.2
Thereafter		441.5
Total Maturities		582.5
Debt Instrument, Unamortized Discount		(2.7)	(1.4)
Total long-term debt		574.4
Unamortized Deferred Financing Costs			(6.3)
Current portion - long-term debt		139.8	4.6
Long-term Debt, Excluding Current Maturities		434.6	581.5
Unamortized Deferred Financing Costs (Subsidiary)		(5.4)	(6.3)
Letter Of Credit Sublimit		75.0
Line of Credit Facility, Additional Borrowing Capacity		100.0
3.95% Senior Notes due 2049 [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	$ 425.0	$ 425.0
Debt Instrument, Interest Rate, Stated Percentage		3.95%
Extinguishment of Debt, Amount	$ 435.0	$ 435.0
Long-term Debt, Gross		425.0
Ten Year Senior Unsecured Bonds At 435 Maturing At April 15 2029 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt		$ 400.0
Debt Instrument, Interest Rate, Stated Percentage		4.35%
Senior Unsecured Bonds at 7.25% maturing in 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.25%
Extinguishment of Debt, Amount		$ 400.0
Make Whole Premium		41.4
Long-term Debt, Gross		$ 380.0	$ 780.0		$ 780.0
Revolving Credit Agreement and Standby Letters of Credit [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum		0.67
First Mortgage Bonds [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Total Debt to Total Capitalization Ratio		0.57
Senior Unsecured Notes At 6.80 Maturing On October 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.75%	6.75%
Extinguishment of Debt, Amount		$ 99.0	$ 101.0
Make Whole Premium		1.5				$ 5.1
Long-term Debt, Gross							$ 200.0
Term Loan Maturing 2022 (DPL) [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		0.0	436.1
Term Loan Maturing 2022 (DPL) [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		0.0	436.1
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		140.0
One Point One Three To One Point One Seven Bonds Maturing In August Two Thousand Twenty [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 140.0
Four Point Two Zero Percentage Of U S Government Note Maturing In February Two Thousand Sixty One [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.20%
Long-term Debt, Gross		$ 17.5	17.7
Four Point Two Zero Percentage Of U S Government Note Maturing In February Two Thousand Sixty One [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.20%
Long-term Debt, Gross		$ 17.5	17.7
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount			60.0
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount			60.0
Revolving Credit Facility [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Total Debt to Total Capitalization Ratio		0.57
Generation [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Disposal Group, Including Discontinued Operations, Long-Term Debt								$ 0.3
Debt [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		$ 1,363.1	1,475.9
Debt [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		$ 574.4	$ 586.1