Realized gains and losses from sale of available for sale securities, net of tax.

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- Definition

ARO obligation for Gypsum landfill

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No definition available.

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- Definition

Adjustment to ARO due to costs evaluation from purchase accounting assessments.

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- Definition

Last Date Debts begin to be repaid

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No definition available.

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Debt maturities minimum period

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- Definition

Partial Reduction to Asset Retirement Obligation Liability

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No definition available.

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- Definition

Percentage Of Inputs To The Fair Value Of Derivative Instruments From Quoted Market Prices

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No definition available.

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- Definition

The estimated net amount of unrealized gains or losses on available for sale securities expected to be reclassified to earnings, net of tax

+ References

No definition available.

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- Definition

Unrealized Gains and Immaterial Unrealized Losses in AOCI, Net of Tax

+ References

No definition available.

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- Definition

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

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-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 21

-Subparagraph a

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- Definition

Amount of asset retirement obligations (ARO) costs incurred (whether capitalized or charged to expense) during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(1)

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-Paragraph 59P

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 22

-Subparagraph c

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- Definition

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 8, 9

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- Definition

Before tax and reclassification adjustments amount of unrealized holding gain (loss) and transfers on available-for-sale securities.

+ References

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(3)

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-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Number 115

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-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

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-Topic 220

-SubTopic 10

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-Paragraph 10A

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- Definition

The estimated net amount of unrealized gains or losses on price risk cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

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Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2011	Nov. 27, 2011	Dec. 31, 2012	Dec. 31, 2011
Debt Maturities Maximum Period			2061
Debt Maturities Minimum Period			2013
Unrealized gains / (losses) on financial instruments, Amount before tax			$ 0.7	$ 0.9
Unrealized gains and immaterial unrealized losses in AOCI, after tax			0.5	0.6
Unrealized gains or losses are expected to be transferred to earnings in the next twelve months.			0.1
Unrealized gains or losses expected to be realized over next twelve months, net of tax			0.1
Costs incurred asset retirement obligation incurred gypsum disposal			0.1
Costs incurred asset retirement obligation incurred purchase accounting adjustment	4.8
Percent of inputs to the fair value of derivative instruments from quoted market prices			98.00%
Gross additions to our existing landfill and asbestos AROs	0.1	0.9
Partial reduction to the ARO liability			0.1
Money market funds	125.0		130.0	125.0
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds			0.1
AvailableForSaleSecuritiesGross Realized Gains Losses Sale Proceeds Net of Tax			0.1
DP&L [Member]
Debt Maturities Maximum Period			2061
Debt Maturities Minimum Period			2013
Unrealized gains / (losses) on financial instruments, Amount before tax			1.6	1.0
Unrealized gains and immaterial unrealized losses in AOCI, after tax			1.0	0.7
Unrealized gains or losses are expected to be transferred to earnings in the next twelve months.			0.1
Unrealized gains or losses expected to be realized over next twelve months, net of tax			0.1
Costs incurred asset retirement obligation incurred gypsum disposal			0.1
Percent of inputs to the fair value of derivative instruments from quoted market prices			98.00%
Gross additions to our existing landfill and asbestos AROs			1.0
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds			0.1
AvailableForSaleSecuritiesGross Realized Gains Losses Sale Proceeds Net of Tax			$ 0.1