Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 28,700,000	$ (249,000,000)
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	35,000,000	35,300,000
Amortization of intangibles		300,000
Deferred income taxes	(1,000,000)	(3,200,000)
Fixed asset impairment		11,500,000
Goodwill Impairment		135,800,000
Changes in certain assets and liabilities:
Accounts receivable	3,800,000	(13,700,000)
Inventories	5,200,000	(8,000,000)
Prepaid taxes	600,000	1,400,000
Taxes applicable to subsequent years	19,100,000	14,000,000
Deferred regulatory costs, net	11,400,000	(7,700,000)
Accounts payable	(20,400,000)	36,900,000
Accrued taxes payable	(24,700,000)	75,600,000
Accrued interest payable	6,800,000	14,500,000
Pension, retiree and other benefits	2,000,000	800,000
Other	(600,000)	(31,600,000)
Net cash provided by operating activities	65,900,000	12,900,000
Cash flows from investing activities:
Capital expenditures	(33,700,000)	(28,400,000)
Decrease (increase) in Restricted Cash	(800,000)	(15,600,000)
Other investing activities, net	300,000
Net cash used for investing activities	(34,400,000)	(45,300,000)
Cash flows from financing activities:
Withdrawals from revolving credit facilities	15,000,000	65,000,000
Repayments of borrowings from revolving credit facilities	(15,000,000)	(65,000,000)
Cash and cash equivalents:
Net change	31,500,000	(32,400,000)
Balance at beginning of period	17,000,000	53,200,000
Cash and cash equivalents at end of period	48,500,000	20,800,000
Supplemental cash flow information:
Interest paid, net of amounts capitalized	20,800,000	15,000,000
Income taxes refunded, net		(300,000)
Non-cash financing and investing activities:
Accruals for capital expenditures	11,200,000	9,400,000
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income	36,500,000	9,400,000
Adjustments to reconcile Net income to Net cash provided by operating activities:
Depreciation and amortization	34,700,000	36,500,000
Deferred income taxes	(700,000)	1,400,000
Changes in certain assets and liabilities:
Accounts receivable	(1,300,000)	(14,800,000)
Inventories	5,200,000	(10,300,000)
Prepaid taxes	500,000	300,000
Taxes applicable to subsequent years	18,300,000	13,500,000
Deferred regulatory costs, net	11,400,000	(7,700,000)
Accounts payable	(20,200,000)	34,000,000
Accrued taxes payable	(20,600,000)	(21,500,000)
Accrued interest payable	(5,900,000)	(5,800,000)
Pension, retiree and other benefits	2,000,000	800,000
Other	(16,300,000)	(25,600,000)
Net cash provided by operating activities	43,600,000	10,200,000
Cash flows from investing activities:
Capital expenditures	(33,100,000)	(27,400,000)
Insurance proceeds	1,500,000
Decrease (increase) in Restricted Cash	(800,000)	(16,000,000)
Other investing activities, net	300,000
Net cash used for investing activities	(32,300,000)	(44,700,000)
Cash flows from financing activities:
Dividends paid on common stock	(10,000,000)
Dividends paid on preferred stock	(200,000)	(200,000)
Borrowings from related party		15,000,000
Withdrawals from revolving credit facilities	15,000,000
Repayments of borrowings from revolving credit facilities	(15,000,000)
Net cash used for financing activities	(10,200,000)	14,800,000
Cash and cash equivalents:
Net change	1,100,000	(19,700,000)
Balance at beginning of period	5,400,000	22,900,000
Cash and cash equivalents at end of period	6,500,000	3,200,000
Supplemental cash flow information:
Interest paid, net of amounts capitalized	12,500,000	12,800,000
Income taxes refunded, net		(300,000)
Non-cash financing and investing activities:
Accruals for capital expenditures	11,200,000	9,400,000
Emission Allowances [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets		(100,000)
Emission Allowances [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets		(100,000)
Renewable Energy Certificates [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets	(200,000)	(1,200,000)
Renewable Energy Certificates [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Payments to Acquire Intangible Assets	$ (200,000)	$ (1,200,000)