Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income/ (loss)	$ 50.4	$ (215.2)
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	69.3	69.2
Amortization of intangibles	0.0	0.6
Deferred income taxes	(17.5)	(2.3)
Goodwill impairment	0.0	135.8
Fixed-asset impairment	0.0	11.5
Changes in certain assets and liabilities:
Accounts receivable	25.0	6.6
Inventories	(4.5)	(12.7)
Prepaid taxes	(0.5)	1.0
Taxes applicable to subsequent years	38.6	33.5
Deferred regulatory costs, net	21.3	(4.3)
Accounts payable	3.3	18.3
Accrued taxes payable	(15.5)	35.8
Accrued interest payable	0.0	(0.4)
Pension, retiree and other benefits	3.8	(6.2)
Other	(2.2)	(18.5)
Net cash provided by operating activities	171.5	52.7
Cash flows from investing activities:
Capital expenditures	(64.8)	(55.2)
Proceeds from sale of business	1.3	0.0
Increase in restricted cash	(8.4)	(11.0)
Other investing activities, net	0.4	1.2
Net cash used by investing activities	(71.7)	(66.5)
Cash flows from financing activities:
Payments of deferred financing costs	(0.1)	(0.1)
Borrowings from revolving credit facilities	15.0	115.0
Repayment of borrowings from revolving credit facilities	(15.0)	(115.0)
Retirement of long-term debt	(0.1)	(0.1)
Net cash used by financing activities	(0.2)	(0.2)
Cash and cash equivalents:
Net change	99.6	(14.0)
Balance at beginning of period	17.0	53.2
Cash and cash equivalents at end of period	116.6	39.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	55.6	59.3
Income taxes paid / (refunded), net	0.5	0.2
Non-cash financing and investing activities:
Accruals for capital expenditures	10.0	7.9
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income/ (loss)	60.4	23.3
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	68.9	71.8
Deferred income taxes	(11.6)	2.7
Changes in certain assets and liabilities:
Accounts receivable	16.2	(0.3)
Inventories	(4.7)	(12.6)
Prepaid taxes	(0.2)	0.0
Taxes applicable to subsequent years	37.4	32.3
Deferred regulatory costs, net	21.3	(4.3)
Accounts payable	3.3	18.4
Accrued taxes payable	(8.0)	(31.6)
Accrued interest payable	0.0	0.1
Pension, retiree and other benefits	3.8	(6.2)
Other	(18.9)	(18.3)
Net cash provided by operating activities	167.9	75.3
Cash flows from investing activities:
Capital expenditures	(63.3)	(53.0)
Insurance proceeds	3.8	0.4
Increase in restricted cash	(8.4)	(11.4)
Other investing activities, net	0.4	1.3
Net cash used by investing activities	(67.7)	(64.2)
Cash flows from financing activities:
Payments of deferred financing costs	0.0	(0.2)
Dividends paid on common stock to parent	(20.0)	(15.0)
Borrowings from revolving credit facilities	15.0	0.0
Issuance of notes payable - related party	0.0	15.0
Repayment of notes payable - related party	0.0	(15.0)
Dividends paid on preferred stock	(0.4)	(0.4)
Repayment of borrowings from revolving credit facilities	(15.0)	0.0
Retirement of long-term debt	(0.1)	(0.1)
Net cash used by financing activities	(20.5)	(15.7)
Cash and cash equivalents:
Net change	79.7	(4.6)
Balance at beginning of period	5.4	22.9
Cash and cash equivalents at end of period	85.1	18.3
Supplemental cash flow information:
Interest paid, net of amounts capitalized	13.5	13.6
Income taxes paid / (refunded), net	0.5	0.2
Non-cash financing and investing activities:
Accruals for capital expenditures	10.0	7.9
Emission Allowances [Member]
Cash flows from investing activities:
Purchase of intangible assets	0.0	(0.1)
Emission Allowances [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Purchase of intangible assets	0.0	(0.1)
Renewable Energy Credits [Member]
Cash flows from investing activities:
Purchase of intangible assets	(0.2)	(1.4)
Renewable Energy Credits [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Purchase of intangible assets	$ (0.2)	$ (1.4)