Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 16.9	$ (51.7)
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	20.1	28.0
Charge for early retirement of debt	0.7	0.0
Deferred income taxes	(41.7)	(4.7)
Impairment of Long-Lived Assets Held-for-use	0.0	66.4
Gain (Loss) on Disposition of Business	(13.6)	0.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0.6	19.4
Changes in certain assets and liabilities:
Accounts receivable	5.9	38.1
Inventories	3.2	0.1
Taxes applicable to subsequent years	19.7	20.2
Deferred regulatory costs, net	(2.1)	(23.8)
Accounts payable	(0.9)	(30.9)
Accrued taxes payable	8.7	(66.0)
Accrued interest payable	17.6	15.9
Security deposits	0.6	17.6
Increase (Decrease) in Self Insurance Reserve	0.0	1.2
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(5.9)	1.3
Other	(6.4)	(4.6)
Net cash provided by operating activities	50.6	26.5
Cash flows from investing activities:
Capital expenditures	(27.3)	(41.4)
Proceeds from sale of business	234.9	0.0
Payments for Removal Costs	(14.5)	0.0
Insurance proceeds	2.8	1.2
Other investing activities, net	(0.5)	0.2
Net cash provided by investing activities	195.4	(40.0)
Cash flows from financing activities:
Repayments of Lines of Credit	(15.0)	0.0
Proceeds from Lines of Credit	25.0	0.0
Retirement of long-term debt	(131.1)	(7.4)
Net cash provided by financing activities	(121.1)	(7.4)
Cash and cash equivalents:
Net change	124.9	(20.9)
Supplemental cash flow information:
Interest paid, net of amounts capitalized	7.0	10.4
Non-cash financing and investing activities:
Accruals for capital expenditures	8.9	10.7
Restricted Cash and Cash Equivalents	151.3	62.7
Non-cash Proceeds from Sale of Business	4.1	0.0
Non-cash capital contribution	45.1	0.0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income	15.7	(41.8)
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	18.6	23.5
Charge for early retirement of debt	0.5	0.0
Deferred income taxes	3.6	0.4
Impairment of Long-Lived Assets Held-for-use	0.0	66.3
Gain (Loss) on Disposition of Business	(12.4)	0.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0.0	19.4
Changes in certain assets and liabilities:
Accounts receivable	(2.3)	28.4
Inventories	(0.2)	0.1
Taxes applicable to subsequent years	17.8	19.8
Deferred regulatory costs, net	(2.1)	(23.8)
Accounts payable	7.7	(24.6)
Accrued taxes payable	(36.3)	(52.7)
Accrued interest payable	0.3	(1.3)
Security deposits	0.6	17.6
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(5.5)	1.3
Other	(0.2)	(0.8)
Net cash provided by operating activities	30.6	31.8
Cash flows from investing activities:
Capital expenditures	(24.6)	(34.1)
Payments for Removal Costs	(14.5)	0.0
Other investing activities, net	(0.3)	0.1
Net cash provided by investing activities	(39.4)	(34.0)
Cash flows from financing activities:
Repayments of Lines of Credit	(15.0)	0.0
Proceeds from Lines of Credit	25.0	0.0
Retirement of long-term debt	(61.1)	(1.1)
Payments of Ordinary Dividends, Common Stock	(23.8)	(9.0)
Issuance of short-term debt - related party	0.0	30.0
Repayments of Related Party Debt	0.0	(35.0)
Proceeds from Contributions from Parent	80.0	0.0
Net cash provided by financing activities	5.1	(15.1)
Cash and cash equivalents:
Net change	(3.7)	(17.3)
Supplemental cash flow information:
Interest paid, net of amounts capitalized	5.5	7.9
Non-cash financing and investing activities:
Accruals for capital expenditures	4.6	8.7
Restricted Cash and Cash Equivalents	$ 1.9	$ 13.3