Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2011 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2010 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2009 THE DAYTON POWER AND LIGHT COMPANY [Member]	Dec. 31, 2011 Successor [Member]	Nov. 27, 2011 Predecessor [Member]	Dec. 31, 2010 Predecessor [Member]	Dec. 31, 2009 Predecessor [Member]
Cash flows from operating activities:
Net income	$ 193.2	$ 277.7	$ 258.9	$ (6.2)	$ 150.5	$ 290.3	$ 229.1
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	134.9	130.7	135.5	11.6	129.4	139.4	145.5
Amortization of other assets				11.6		0	0
Deferred income taxes	50.7	54.3	200.1	0.1	65.5	59.9	201.6
Gain on liquidation of DPL stock, held in trust	(14.6)	0	0
Charge for early redemption of debt					15.3
Changes in certain assets and liabilities:
Accounts receivable	5.3	15.2	25.7	(12.3)	14.6	(1.5)	39.3
Inventories	(15.5)	10.1	(20.5)	(2.5)	(11.5)	10.4	(20.6)
Prepaid taxes	8.1	(8.9)	0	0.6	7.1	(9.0)	0
Taxes applicable to subsequent years	(9.0)	(3.6)	(1.3)	(71.2)	58.4	(4.1)	(1.5)
Deferred regulatory costs, net	(12.6)	21.8	(23.6)	0.1	(14.4)	21.8	(23.6)
Accounts payable	7.1	16.9	(65.9)	6.6	(0.6)	17.8	(65.0)
Accrued taxes payable	15.2	1.7	(0.9)	78.5	(58.6)	1.2	(2.4)
Accrued interest payable	0.2	(5.4)	0.2	6.4	(8.1)	(5.1)	(1.5)
Pension, retiree and other benefits	(24.0)	(58.2)	15.2	10.2	(34.2)	(58.2)	15.2
Unamortized investment tax credit	(2.5)	(2.8)	(2.8)	(0.2)	(2.3)	(2.8)	(2.8)
Insurance and claims costs				(0.1)	4.3	(6.1)	(1.4)
Other deferred debits, DPL stock held in trust				(26.9)		0	0
Other	19.3	(3.1)	(6.9)	(7.2)	10.1	10.2	12.8
Net cash provided by operating activities	355.8	446.4	513.7	(0.9)	325.5	464.2	524.7
Cash flows from investing activities:
Capital expenditures	(204.5)	(150.0)	(167.4)	(30.5)	(174.2)	(152.7)	(172.3)
Proceeds from sale of property - other				0		0	1.2
Purchase of MC Squared					(8.3)
Purchases of short-term investments and securities				0	(1.7)	(86.4)	(20.7)
Sales of short-term investments and securities				0	70.9	17.1	25.7
Proceeds from liquidation of DPL stock, held in trust	26.9	0	0
Other	1.0	1.4	1.4	(0.4)	1.5	1.4	1.4
Net cash used for investing activities	(176.6)	(148.6)	(166.0)	(30.9)	(111.8)	(220.6)	(164.7)
Cash flows from financing activities:
Dividends paid on common stock	(220.0)	(300.0)	(325.0)	(63.0)	(113.0)	(139.7)	(128.8)
Dividends paid on preferred stock	(0.9)	(0.9)	(0.9)
Proceeds from liquidation of DPL stock, held in trust				26.9		0	0
Early redemption of Capital Trust II debt					(122.0)		(52.4)
Premium paid for early redemption of debt					(12.2)		(3.7)
Payment of MC Squared debt					(13.5)
Payment of long-term debt	(0.1)	0	0	0	(297.5)	0	(175.0)
Issuance of long-term debt				125.0	300.0	0	0
Withdrawals from revolving credit facilities	50.0		260.0		50.0		260.0
Repayments of borrowings from revolving credit facilities	(50.0)		(260.0)		(50.0)		(260.0)
Cash contribution from parent	20.0	0	0
Withdrawal of restricted funds held in trust, net	0	0	14.5	0		0	14.5
Repurchase of DPL common stock				0		(56.4)	(64.4)
Repurchase of warrants				0		0	(25.2)
Exercise of stock options				0	1.6	1.4	9.0
Exercise of warrants				0	14.7	0	77.7
Tax impact related to exercise of stock options				0	1.4	0.2	0.7
Net cash used for financing activities	(201.0)	(300.9)	(311.4)	88.9	(240.5)	(194.5)	(347.6)
Cash and cash equivalents:
Net change	(21.8)	(3.1)	36.3	57.1	(26.8)	49.1	12.4
Assumption of cash aquisition				19.2		0	0
Balance at beginning of period	54.0	57.1	20.8		124.0	74.9	62.5
Cash and cash equivalents at end of period	32.2	54.0	57.1	173.5	97.2	124.0	74.9
Supplemental cash flow information:
Interest paid, net of amounts capitalized	39.2	45.1	39.5	6.0	62.0	77.1	84.3
Income taxes paid, net	13.9	87.0	(94.7)	0	25.6	87.1	(94.6)
Assumption of debit with acquisition				1,250.0		0	0
Non-cash financing and investing activities:
Accruals for capital expenditures	26.5	23.2	20.8	7.6	18.9	23.2	20.8
Long-term liability incurred for purchase of assets	$ 18.7				$ 18.7