Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 70.1	$ (94.6)	$ (485.2)
Adjustments to reconcile Net income / (loss) to Net cash from operating activities
Depreciation and amortization	50.2	106.9	132.3
Amortization of deferred financing costs	5.5	3.6	5.6
Unrealized loss (gain) on derivatives	(0.2)	(1.7)	(4.3)
Deferred income taxes	(9.1)	(22.2)	(306.2)
Charge for early redemption of debt	6.5	3.3	3.1
Impairment of Long-Lived Assets Held-for-use	2.8	0.0	23.9
Impairment of Long-Lived Assets Held-for-use, Including Discontinued Operation	2.8	175.8	859.0
Gain (Loss) on Disposition of Business	13.3	(14.0)	(49.2)
Gain (Loss) on Disposition of Business	(11.7)	0.0	0.0
Loss / (Gain) on asset disposal, net	(2.0)	16.1	(0.1)
Changes in certain assets and liabilities:
Accounts receivable	45.7	18.1	25.6
Inventories	14.8	7.7	32.0
Taxes applicable to subsequent years	0.1	2.3	0.2
Deferred regulatory costs, net	(9.2)	(23.7)	4.1
Accounts payable	(16.3)	(36.3)	15.1
Accrued taxes payable	37.4	(3.7)	45.1
Accrued interest payable	(2.1)	(1.3)	(3.7)
Pension, retiree and other benefits	(3.4)	4.7	3.0
Insurance and claims costs	1.1	(2.4)	(0.5)
Other	0.7	(6.9)	(8.8)
Net cash provided by operating activities	205.9	131.7	267.1
Cash flows from investing activities:
Capital expenditures	(103.6)	(121.5)	(148.5)
Proceeds from disposal and sale of business	234.9	70.1	0.0
Payments for Removal Costs	(14.5)	0.0	0.0
Proceeds from Sale of Property, Plant, and Equipment	10.6	0.1	0.2
Insurance proceeds	3.0	12.3	6.3
Other investing activities, net	(0.5)	(0.3)	0.5
Net cash provided by / (used in) investing activities	129.9	(39.3)	(141.5)
Cash flows from financing activities:
Deferred financing costs	0.0	0.0	(8.6)
Preferred Stock, Redemption Amount	0.0	0.0	(23.5)
Retirement of debt	(240.5)	(159.5)	(577.8)
Premium paid for early redemption of debt	0.0	(0.1)	0.0
Issuance of long-term debt	0.0	0.0	442.8
Borrowings from revolving credit facilities	30.0	102.5	15.0
Repayment of borrowings from revolving credit facilities	(40.0)	(92.5)	(15.0)
Net cash from financing activities	(250.5)	(149.6)	(167.1)
Net Cash Provided by (Used in) Discontinued Operations	1.5	27.5	15.8
Cash and cash equivalents:
Net increase / (decrease) in cash	86.8	(29.7)	(25.7)
Restricted Cash and Cash Equivalents	111.7	24.9	54.6
Supplemental cash flow information:
Interest paid, net of amounts capitalized	93.7	105.2	103.8
Income taxes paid / (refunded), net	(1.4)	0.0	0.3
Non-cash financing and investing activities:
Accruals for capital expenditures	10.4	12.9	16.2
Non-cash Proceeds from Sale of Business	4.1	0.0	0.0
Non-cash capital contribution	40.0	97.1	0.0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income (loss)	86.7	17.0	(772.7)
Adjustments to reconcile Net income / (loss) to Net cash from operating activities
Depreciation and amortization	74.5	87.2	120.3
Amortization of deferred financing costs	3.1	1.1	2.9
Unrealized loss (gain) on derivatives	0.0	(1.0)	(4.2)
Deferred income taxes	16.3	8.1	(477.5)
Charge for early redemption of debt	0.6	1.1	0.5
Impairment of Long-Lived Assets Held-for-use	0.0	66.3	1,353.5
Gain (Loss) on Disposition of Business	(12.4)	0.0	0.0
Loss / (Gain) on asset disposal, net	0.2	15.7	(0.1)
Changes in certain assets and liabilities:
Accounts receivable	13.5	14.6	(8.3)
Inventories	(0.3)	10.3	32.2
Prepaid taxes	0.0	0.0	2.7
Taxes applicable to subsequent years	(1.3)	6.4	0.0
Deferred regulatory costs, net	(9.2)	(23.7)	4.1
Accounts payable	3.8	(48.7)	14.6
Accrued taxes payable	(12.7)	(17.5)	(10.5)
Accrued interest payable	(0.4)	(1.3)	(2.0)
Pension, retiree and other benefits	(2.4)	4.8	3.0
Other	11.0	(5.0)	(21.3)
Net cash provided by operating activities	195.8	135.4	237.2
Cash flows from investing activities:
Capital expenditures	(93.1)	(101.7)	(128.3)
Payments for Removal Costs	(14.5)	0.0	0.0
Proceeds from Sale of Property, Plant, and Equipment	10.6	0.0	0.2
Insurance proceeds	0.4	12.5	6.1
Other investing activities, net	(0.3)	(0.3)	0.4
Net cash provided by / (used in) investing activities	(96.9)	(89.5)	(121.6)
Cash flows from financing activities:
Dividends paid on preferred stock	0.0	0.0	(0.7)
Deferred financing costs	0.0	0.0	(8.5)
Preferred Stock, Redemption Amount	0.0	0.0	(23.5)
Retirement of debt	(64.5)	(104.5)	(445.3)
Proceeds from Contributions from Parent	80.0	70.0	0.0
Premium paid for early redemption of debt	0.0	(0.4)	0.0
Issuance of long-term debt	0.0	0.0	442.8
Borrowings from revolving credit facilities	30.0	40.0	0.0
Repayment of borrowings from revolving credit facilities	(40.0)	(30.0)	0.0
Dividends paid on common stock to parent	(43.8)	(39.0)	(70.0)
Borrowings from related party	0.0	30.0	10.0
Repayment of borrowings from related party	0.0	(35.0)	(40.0)
Net cash from financing activities	(38.3)	(68.9)	(135.2)
Net Cash Provided by (Used in) Discontinued Operations	0.0	27.0	15.8
Cash and cash equivalents:
Net increase / (decrease) in cash	60.6	4.0	(3.8)
Restricted Cash and Cash Equivalents	66.2	5.6	1.6
Supplemental cash flow information:
Interest paid, net of amounts capitalized	22.9	28.4	21.4
Income taxes paid / (refunded), net	13.1	28.1	0.3
Non-cash financing and investing activities:
Accruals for capital expenditures	10.8	19.7	14.8
Subsidiary of Common Parent [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Non-cash financing and investing activities:
Equity Settlement of Related Party Payable	0.0	$ 0.0	7.5
Generation [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Non-cash financing and investing activities:
Disposal Group, Including Discontinued Operation, Net Assets	$ (10.0)		$ 0.0