Debt Instrument, Debt Covenant, Debt to EBITDA Ratio, Number of Quarters

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Debt Instrument, Number of Financial Covenants

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Letter Of Credit Sublimit

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Letter of Credit, Outstanding, Number of Instruments Held

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Line of Credit Facility, Additional Borrowing Capacity

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

Name:	us-gaap_ExtinguishmentOfDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt, after unamortized discount or premium, scheduled 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.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Debt Obligations (Narrative) (Details)			6 Months Ended
Debt Obligations (Narrative) (Details)	Aug. 03, 2015 USD ($)	Jul. 01, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2015 USD ($) letter_of_credit debt_covenant fiscal_quarter	Jul. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Current portion - long-term debt				$ 444,900,000		$ 20,100,000
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				444,900,000		100,000
Revolving Credit Agreeement with Bank Group Expiring 2018 [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement			$ 300,000,000.0
Unsecured revolving credit agreement, term			5 years
Letter of credit sublimit			$ 100,000,000.0
Line of credit facility, additional borrowing capacity			100,000,000.0
Line of credit outstanding				$ 10,000,000
Number of letters of credit outstanding \| letter_of_credit				2
Letters of credit outstanding				$ 1,400,000
Line of credit facility, remaining borrowing capacity				$ 163,600,000
Revolving Credit Agreement and Standby Letters of Credit [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Number of financial covenants \| debt_covenant				2
Number of prior quarters included in EBITDA to interest calculation \| fiscal_quarter				4
Pollution Control Series Maturing in January 2028 - 4.70% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.70%
Term loan outstanding						35,300,000
Pollution Control Series Maturing in January 2028 - 4.70% [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed		$ 35,300,000
Debt instrument interest percentage		4.70%
Term loan outstanding				$ 0		35,300,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.80%
Term loan outstanding						179,100,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed	$ 137,800,000	$ 41,300,000
Debt instrument interest percentage	4.80%	4.80%
Repayments of debt	$ 37,800,000
Term loan outstanding				$ 0		179,100,000
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Variable rate notes issued	200,000,000.0
Term loan outstanding				200,000,000
Pollution control series maturing in November 2040 [Member]
Debt Instrument [Line Items]
Term loan outstanding						100,000,000
Pollution control series maturing in November 2040 [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed	$ 100,000,000
Term loan outstanding				0		100,000,000
Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				0		20,000,000
Term loan outstanding					$ 160,000,000	$ 140,000,000
Bank Term Loan Maturing July 2020 [Member]
Debt Instrument [Line Items]
Term loan outstanding				$ 125,000,000	125,000,000
Revolving Credit Agreement with Bank Group Expiring 2020 [Member] \| THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement					175,000,000.0
Letter of credit sublimit					50,000,000.0
Line of credit facility, additional borrowing capacity					100,000,000.0
DPL Revolving Credit Facility [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement			$ 100,000,000.0		205,000,000.0
Unsecured revolving credit agreement, term			5 years
Letter of credit sublimit			$ 100,000,000.0		200,000,000.0
Line of credit facility, additional borrowing capacity			$ 50,000,000.0		$ 95,000,000.0
Number of letters of credit outstanding \| letter_of_credit				1
Letters of credit outstanding				$ 2,300,000
Line of credit facility, remaining borrowing capacity				$ 202,700,000
Revolving Credit Agreement and Term Loan [Member]
Debt Instrument [Line Items]
Number of financial covenants \| debt_covenant				2
Number of prior quarters included in EBITDA to interest calculation \| fiscal_quarter				4
Number of prior quarters included in debt to EBITDA ratio \| fiscal_quarter				4