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Debt Issuance Costs and Unamortized Debt Discount

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The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt and excluding interest and repayment of debt principal, reflected as a % of the principal paid.

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Amount of the total principal payments made during the annual reporting period.

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Interest rate stated in the contractual debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

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

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Increase for additional borrowings on the credit facility during the period.

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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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Carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt, including legal costs and prepayment penalties, and excluding interest and repayment of debt principal.

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The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

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

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Carrying value as of the balance sheet date of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer), excluding the current portion, if any. Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Debt Obligations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	0 Months Ended	9 Months Ended			1 Months Ended		1 Months Ended	3 Months Ended			1 Months Ended	9 Months Ended			1 Months Ended
	Feb. 28, 2011	Feb. 23, 2011	Sep. 30, 2011	Sep. 30, 2010	Mar. 01, 2011	Mar. 01, 2011 DP&L [Member] U.S. Government note maturing in February 2061 - 4.20% [Member]	Sep. 30, 2011 DP&L [Member] U.S. Government note maturing in February 2061 - 4.20% [Member]	Aug. 31, 2011 DP&L [Member] Revolving Credit Agreement with Bank Group [Member]	Apr. 20, 2010 DP&L [Member] Revolving Credit Agreement with Bank Group [Member]	Sep. 30, 2011 DP&L [Member] Revolving Credit Agreement with Bank Group [Member]	Apr. 21, 2009 DP&L [Member] Revolving Credit Agreement with Bank Group [Member]	Aug. 31, 2011 Revolving Credit Agreement with Bank Group [Member]	Sep. 30, 2011 Five Year Senior Unsecured Notes at 6.50% maturing on October 15, 2016 [Member]	Sep. 30, 2011 Ten Year Senior Unsecured Notes at 7.25% maturing at October 15, 2021 [Member]	Sep. 30, 2011 Unsecured Term Loan Agreement [Member]	Sep. 30, 2011 Senior Notes Maturing in September 2011 - 6.875% [Member]	Jun. 30, 2011 DP&L [Member]	Dec. 04, 2008 DP&L [Member]	Nov. 21, 2006 DP&L [Member]
Additional principal amount of senior notes to be raised			$ 1,250										$ 450	$ 800
Debt Instrument, Maturity Date								Aug. 24, 2015				Aug. 24, 2014	Oct. 15, 2016	Oct. 15, 2021
Unsecured revolving credit agreement								200	200		100	125			425				220
Increase additional facility								50	50
Letter of credit sublimit									50	50
Letters of credit outstanding			0							0							0
Collateralized debt																		100
Loans Payable, Noncurrent															300
Purchase of principal amount		122.0
Interest expenses		12.2
Premium percentage		10.00%
Debt issuance costs and unamortized debt discount		3.1
Repayments of Debt	13.5															297.4
Payments to Acquire Productive Assets			$ 141.3	$ 113.7		$ 18.7
Debt Instrument, Interest Rate, Stated Percentage					4.20%		4.20%						6.50%	7.25%		6.875%