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Long Term Debt Maturities Repayments Of Principal, Total

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Long Term Debt Range Adjusted To Fair Value At Merger End

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Long Term Debt Range Adjusted To Fair Value at Merger Start

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Total Long-term Debt At Subsidiary With Purchase Accounting Adjustments

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Total Maturities Before Unamortized Adjustments

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Unamortized adjustments to market value from purchase accounting

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Unamortized Deferred Financing Costs

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Unamortized Deferred Financing Costs (Subsidiary)

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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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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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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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt discount (premium).

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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 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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Debt (Long-term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Debt (Long-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Oct. 01, 2017	Dec. 31, 2016	Jan. 06, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 4.7
Capital Lease Obligations	0.2		$ 0.4
Unamortized Deferred Financing Costs	(6.8)		(8.8)
Debt Instrument, Unamortized Discount (Premium), Net	(0.5)		(0.6)
Total long-term debt at subsidary	646.8		747.2
Less: current portion	(4.7)		(29.7)
Long-term debt, net of current portion	$ 1,700.4		1,828.7
Debt maturity date, earliest	2019
Debt maturity date, latest	2061
Long-term Debt, Maturities, Repayments of Principal in Year Two	$ 224.5
Long-term Debt, Maturities, Repayments of Principal in Year Three	254.6
Long-term Debt, Maturities, Repayments of Principal in Year Four	784.6
Long-term Debt, Maturities, Repayments of Principal in Year Five	422.9
Long-term Debt, Maturities, Repayments of Principal after Year Five	32.7
Total Maturities Before Unamortized Adjustments	1,724.0
Unamortized adjustments to market value from purchase accounting	2.5
Long Term Debt Maturities Repayments Of Principal, Total	1,721.5
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	4.6
Capital Lease Obligations	0.0		0.4
Unamortized Deferred Financing Costs	(9.8)		(11.7)
Unamortized Deferred Financing Costs (Subsidiary)	(9.8)		(10.7)
Debt Instrument, Unamortized Discount	(2.0)		(2.2)
Debt Instrument, Unamortized Discount (Premium), Net	(2.0)		(5.5)
Less: current portion	(4.6)		(4.6)
Long-term debt, net of current portion	642.0		731.5
Long-term Debt, Maturities, Repayments of Principal in Year Two	4.6
Long-term Debt, Maturities, Repayments of Principal in Year Three	204.6
Long-term Debt, Maturities, Repayments of Principal in Year Four	4.6
Long-term Debt, Maturities, Repayments of Principal in Year Five	422.9
Long-term Debt, Maturities, Repayments of Principal after Year Five	17.1
Total Maturities Before Unamortized Adjustments	658.4
Long Term Debt Maturities Repayments Of Principal, Total	656.4
Term Loan Maturing 2022 (DPL) [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 440.6		445.0
Debt instrument maturity year	Aug. 24, 2022
Term Loan Maturing 2022 (DPL) [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 440.6		$ 445.0
Debt instrument maturity year	Aug. 24, 2022
First Mortgage Bonds Maturing in 2016 - 1.875%
Debt Instrument [Line Items]
Debt instrument interest percentage			1.875%
First Mortgage Bonds Maturing in 2016 - 1.875% \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage			1.875%
Pollution Control Series Maturing in 2036 - 4.80% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 0.0		$ 100.0
Debt instrument maturity year	Sep. 01, 2036
Debt instrument interest percentage	4.80%
Pollution Control Series Maturing in 2036 - 4.80% [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 0.0		100.0
Debt instrument maturity year	Sep. 01, 2036
Debt instrument interest percentage	4.80%
Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b)
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 200.0		200.0
Debt instrument maturity year	Aug. 01, 2020
Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b) \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 200.0		200.0
Debt instrument maturity year	Aug. 01, 2020
U.S. Government note maturing in 2061 - 4.20% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 17.8		18.0
Debt instrument maturity year	Feb. 01, 2061
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	$ 17.8		18.0
Debt instrument maturity year	Feb. 01, 2061
Debt instrument interest percentage	4.20%
Bank Term Loan Maturing July 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 70.0		125.0
Bank Term Loan maturing in May 2018 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	Jul. 31, 2020
Senior Unsecured Bonds at 6.50% maturing in 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross				$ 130.0
Debt instrument interest percentage				6.50%
Five Year Senior Unsecured Notes At6.75 Maturing October152019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 200.0		200.0
Debt instrument maturity year	Oct. 01, 2019
Debt instrument interest percentage	6.75%
Senior Unsecured Bonds at 7.25% maturing in 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 780.0		780.0
Debt instrument maturity year	Oct. 01, 2021
Debt instrument interest percentage	7.25%
Note to DPL Capital Trust II Maturing in 2031 - 8.125% [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 15.6		$ 15.6
Debt instrument maturity year	Sep. 01, 2031
Debt instrument interest percentage	8.125%
Minimum [Member] \| Term Loan Maturing 2022 (DPL) [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum (Deprecated 2016-01-31)	4.00%		4.00%
Minimum [Member] \| Term Loan Maturing 2022 (DPL) [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum (Deprecated 2016-01-31)	4.00%		4.00%
Minimum [Member] \| Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b)
Debt Instrument [Line Items]
Debt instrument interest percentage	1.52%		1.29%
Minimum [Member] \| Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b) \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	1.52%
Minimum [Member] \| Bank Term Loan maturing in May 2018 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	3.02%		2.67%
Maximum [Member] \| Term Loan Maturing 2022 (DPL) [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum (Deprecated 2016-01-31)	4.60%		4.00%
Maximum [Member] \| Term Loan Maturing 2022 (DPL) [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum (Deprecated 2016-01-31)	4.60%		4.00%
Maximum [Member] \| Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b)
Debt Instrument [Line Items]
Debt instrument interest percentage	1.92%		1.42%
Maximum [Member] \| Tax-exempt First Mortgage Bonds - rates from: 1.52% - 1.92% (a) and 1.29% - 1.42% (b) \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	1.92%
Maximum [Member] \| Bank Term Loan maturing in May 2018 [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage	4.10%		3.02%
Debt [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities	$ 1,705.1		$ 1,858.4
Debt [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities	$ 646.6		736.1
Generation [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Disposal Group, Including Discontinued Operations, Long-Term Debt		$ (0.3)	$ (13.4)