Debt Covenant, Interest Coverage Ratio, Minimum

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- Definition

Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum

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No definition available.

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Debt Instrument, Debt Covenant, EBITDA to Interest Calculation, Number of Quarters

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Debt Instrument, Number of Financial Covenants

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Early prepayment rate - prepayments prior to July 3, 2018 must be at this rate

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- Definition

Interest Coverage Ratio

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- Definition

Letter Of Credit Sublimit

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Line of Credit Facility, Additional Borrowing Capacity

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- Definition

After separation required compliance with the financial covenant, shall be suspended from 1/1/17 to 12/31/17 if during such time DP&L's LT indebtedness (as determined by the PUCO) is less than or equal to $750.0 million.

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Standard Repayment Rate - Repayment rate after July 31, 2018

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- Definition

Total Debt to Total Capitalization Ratio

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- Definition

Unamortized Deferred Financing Costs

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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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Face (par) amount of debt instrument at time of issuance.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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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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- Definition

Gross amount of debt extinguished.

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No definition available.

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- Definition

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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- Definition

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

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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 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 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 (Narrative) (Details) $ in Millions		6 Months Ended		9 Months Ended		12 Months Ended
Debt (Narrative) (Details) $ in Millions	Jun. 06, 2019 USD ($)	Dec. 31, 2018 USD ($) fiscal_quarter	Jul. 03, 2018	Sep. 30, 2019 USD ($) fiscal_quarter debt_covenant	Sep. 30, 2018 USD ($) debt_covenant	Dec. 31, 2018 USD ($) fiscal_quarter	Sep. 30, 2018 USD ($) debt_covenant	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 03, 2018	Aug. 03, 2015 USD ($)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 175.0
Current portion - long-term debt		$ 4.6				$ 4.6
Letter of credit sublimit				75.0
Line of credit facility, additional borrowing capacity				100.0
Proceeds from Issuance of Long-term Debt				422.3	$ 0.0	0.0		$ 0.0	$ 442.8
Unamortized Deferred Financing Costs								(9.8)
Current portion - long-term debt		4.6		$ 139.6		$ 4.6		4.6
Debt Covenant, Interest Coverage Ratio, Minimum				2.50		2.50
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum						0.65
Long Term Indebtedness, Less than or Equal to						$ 750.0	$ 750.0	750.0
Long-term Debt, Excluding Current Maturities		581.5		$ 434.6		581.5		642.0
Long-term Debt, Maturities, Repayments of Principal in Year Two		144.7				144.7
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
Long-term Debt, Gross				$ 425.0
Extinguishment of debt, amount	$ 435.0
Debt instrument interest percentage				3.95%
Term Loan Maturing 2022 (DPL) [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 436.1				$ 436.1		440.6
Eurodollar rate Term Loan B [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage		3.25%				3.25%				2.00%
Base Rate Term Loan B [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage		2.25%				2.25%				1.00%
Revolving Credit Agreement and Standby Letters of Credit [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Number of financial covenants \| debt_covenant				2	2		2
Number of prior quarters included in debt to EBITDA ratio \| fiscal_quarter		4		4		4
Interest Coverage Ratio				9.36		8.09
U.S. Government note maturing in 2061 - 4.20% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.20%
U.S. Government note maturing in 2061 - 4.20% [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 17.7		$ 17.6		$ 17.7		17.8
Debt instrument interest percentage		4.20%				4.20%
Term Loan Maturing 2022 [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 436.1		$ 0.0		$ 436.1
Early prepayment rate			101.00%
Standard Repayment Rate		100.00%
First Mortgage Bonds [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum				0.65			0.75
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 140.0		$ 140.0		140.0
Extinguishment of debt, amount				60.0		60.0
Debt Instrument, Face Amount											$ 200.0
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		$ 140.0		140.0		200.0
Revolving Credit Facility [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Covenant, Total Debt to Total Capitalization Ratio, Maximum				0.67
Total Debt to Total Capitalization Ratio				0.58
Debt [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		$ 586.1				$ 586.1		$ 646.6
Minimum [Member] \| Term Loan Maturing 2022 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage		4.01%				4.01%
Debt Instrument, Interest Rate, Effective Percentage				4.50%
Minimum [Member] \| Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				2.97%
Minimum [Member] \| Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage		1.52%				1.52%
Maximum [Member] \| Term Loan Maturing 2022 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.53%
Debt Instrument, Interest Rate, Effective Percentage		4.60%				4.60%
Maximum [Member] \| Pollution control series maturing in November 2040 - variable rates: 0.04% - 0.26% and 0.06% - 0.32% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				3.07%
Maximum [Member] \| Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage		1.92%				1.92%