Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 THE DAYTON POWER AND LIGHT COMPANY [Member]	Sep. 30, 2011 THE DAYTON POWER AND LIGHT COMPANY [Member]	Sep. 30, 2012 Successor [Member]	Sep. 30, 2011 Predecessor [Member]
Cash flows from operating activities:
Net income	$ 58.3	$ 147.4	$ (1,777.3)	$ 142.3
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	107.3	100.3	95.6	106.0
Amortization of intangibles			71.2
Amortization of debt market value adjustments			(14.2)
Deferred income taxes	(3.4)	56.1	(10.5)	70.5
Fixed asset impairment	80.8
Charge for early redemption of debt				15.3
Goodwill Impairment			1,850.0
Changes in certain assets and liabilities:
Accounts receivable	13.0	26.4	(10.2)	21.1
Inventories	28.1	(9.0)	29.5	(9.1)
Prepaid taxes	0.8	(11.5)	0.6	(27.0)
Taxes applicable to subsequent years	56.2	47.1	59.9	47.7
Deferred regulatory costs, net	2.4	7.9	2.7	7.9
Accounts payable	(16.3)	(14.9)	(16.7)	(13.4)
Accrued taxes payable	(35.2)	(58.5)	(49.4)	(58.2)
Accrued interest payable	7.4	7.4	25.2	(3.1)
Pension, retiree and other benefits	24.4	(31.7)	24.4	(31.7)
Unamortized investment tax credit	(1.9)	(2.1)	(0.2)	(2.1)
Insurance and claims costs			(1.3)	4.1
Recognition of deferred SECA revenue	(17.8)		(17.8)
Other	(4.3)	29.3	(11.8)	3.6
Net cash provided by operating activities	299.8	294.2	249.7	273.9
Cash flows from investing activities:
Capital expenditures	(161.7)	(139.9)	(163.1)	(141.3)
Purchase of MC Squared				(8.3)
Increase (Decrease) in Restricted Cash	(5.2)	(7.4)	(0.4)	(9.1)
Purchases of short-term investments and securities				(1.7)
Sales of short-term investments and securities				70.9
Other		1.4		1.5
Net cash used for investing activities	(166.9)	(145.9)	(163.5)	(88.0)
Cash flows from financing activities:
Dividends paid on common stock	(145.0)	(180.0)	(45.0)	(113.8)
Dividends paid on preferred stock	(0.6)	(0.6)
Payment to former warrant holders			(9.0)
Deferred Finance Costs			(0.3)
Early redemption of Capital Trust II debt				(122.0)
Premium paid for early redemption of debt				(12.2)
Payment of MC Squared debt				(13.5)
Payment of long-term debt	(0.1)		(0.1)	(297.4)
Issuance of long-term debt				300.0
Withdrawals from revolving credit facilities		50.0		50.0
Repayments of borrowings from revolving credit facilities		(50.0)		(50.0)
Contributions to additional paid-in capital from parent			0.3
Exercise of stock options				1.6
Exercise of warrants				14.7
Tax impact related to exercise of stock options				0.3
Net cash used for financing activities	(145.7)	(180.6)	(54.1)	(242.3)
Cash and cash equivalents:
Net change	(12.8)	(32.3)	32.1	(56.4)
Balance at beginning of period	32.2	54.0	173.5	124.0
Cash and cash equivalents at end of period	19.4	21.7	205.6	67.6
Supplemental cash flow information:
Interest paid, net of amounts capitalized	22.6	22.2	78.1	49.4
Income taxes paid, net	30.3	13.9	43.0	25.5
Non-cash financing and investing activities:
Accruals for capital expenditures	12.5	14.8	12.5	14.8
Long-term liability incurred for purchase of assets		$ 18.7		$ 18.7