Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 42.8	$ 33.6
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	65.1	62.5
Amortization of intangibles	3.5	47.0
Amortization of debt market value adjustments	(9.5)	(9.5)
Deferred income taxes	24.3	(2.4)
Changes in certain assets and liabilities:
Accounts receivable	33.3	9.6
Inventories	9.2	(1.2)
Prepaid taxes	0.5	0.3
Taxes applicable to subsequent years	34.9	40.7
Deferred regulatory costs, net	7.7	0.1
Accounts payable	(10.7)	7.9
Accrued taxes payable	(43.0)	(51.3)
Accrued interest payable	0.8	1.5
Pension, retiree and other benefits	6.4	4.6
Unamortized investment tax credit	(0.3)	(0.1)
Other	(6.9)	8.8
Net cash provided by operating activities	158.1	152.1
Cash flows from investing activities:
Capital expenditures	(67.2)	(110.5)
Increase (Decrease) in Restricted Cash	1.8	(5.6)
Other	(1.1)
Net cash used for investing activities	(68.3)	(119.5)
Cash flows from financing activities:
Dividends paid on common stock		(45.0)
Payment to former warrant holders		(9.0)
Deferred Finance Costs	(7.3)
Payment of long-term debt	(425.1)	(0.1)
Issuance of long-term debt	200.0
Withdrawals from revolving credit facilities	50.0
Contributions to additional paid-in capital from parent		0.3
Net cash used for financing activities	(182.4)	(53.8)
Cash and cash equivalents:
Net change	(92.6)	(21.2)
Balance at beginning of period	192.1	173.5
Cash and cash equivalents at end of period	99.5	152.3
Supplemental cash flow information:
Interest paid, net of amounts capitalized	68.9	66.7
Income taxes paid/(refund), net	(19.7)	21.6
Non-cash financing and investing activities:
Accruals for capital expenditures	9.4	25.3
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income	60.5	69.4
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	68.7	70.8
Deferred income taxes	23.7	3.3
Changes in certain assets and liabilities:
Accounts receivable	30.8	20.1
Inventories	9.1	(2.5)
Prepaid taxes	0.7	0.4
Taxes applicable to subsequent years	33.3	38.4
Deferred regulatory costs, net	8.0	(0.1)
Accounts payable	(10.6)	6.5
Accrued taxes payable	(29.8)	(46.8)
Accrued interest payable	0.5	5.2
Pension, retiree and other benefits	6.4	4.6
Unamortized investment tax credit	(1.3)	(1.3)
Other	(4.6)	14.5
Net cash provided by operating activities	195.4	182.5
Cash flows from investing activities:
Capital expenditures	(66.8)	(109.5)
Increase (Decrease) in Restricted Cash	1.8	(5.6)
Other	(1.2)
Net cash used for investing activities	(68.0)	(118.5)
Cash flows from financing activities:
Dividends paid on common stock	(130.0)	(70.0)
Dividends paid on preferred stock	(0.4)	(0.4)
Payment of long-term debt	(0.1)	(0.1)
Net cash used for financing activities	(130.5)	(70.5)
Cash and cash equivalents:
Net change	(3.1)	(6.5)
Balance at beginning of period	28.5	32.2
Cash and cash equivalents at end of period	25.4	25.7
Supplemental cash flow information:
Interest paid, net of amounts capitalized	20.3	14.4
Income taxes paid/(refund), net	(19.8)	16.6
Non-cash financing and investing activities:
Accruals for capital expenditures	9.4	25.3
Renewable Energy Certificates [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets	(1.8)	(3.4)
Renewable Energy Certificates [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets	$ (1.8)	$ (3.4)