Consolidated Statements of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 775.9
Cost of revenues:
Net fuel cost	17.5	$ 9.0	$ 17.4
Gross margin	453.4	443.9	497.7
Utilities Operating Expense, Maintenance and Operations	156.8	186.1	213.5
Depreciation and amortization	73.1	76.1	73.6
Taxes, Miscellaneous	73.5	77.1	68.4
Fixed-asset impairment (Note 14)	2.8	0.0	23.9
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.0	0.6	0.7
Gain (Loss) on Disposition of Business	(11.7)	0.0	0.0
Operating Expenses	317.9	338.7	378.7
Operating income	135.5	105.2	119.0
Other income / (expense), net
Interest expense	(98.0)	(110.0)	(107.4)
Charge for early redemption of debt	(6.5)	(3.3)	(3.1)
Other income	0.9	1.6	3.9
Other expense, net	(103.6)	(111.7)	(106.6)
Income / (loss) from continuing operations before income tax	31.9	(6.5)	12.4
Income tax expense / (benefit) from continuing operations	0.7	(5.0)	(2.4)
Net income / (loss) from continuing operations	31.2	(1.5)	14.8
Income / (loss) from discontinued operations before income tax	70.5	(127.4)	(806.4)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	(1.6)	14.0	49.2
Income tax expense / (benefit) from discontinued operations	30.0	(20.3)	(257.2)
Net income / (loss) from discontinued operations	38.9	(93.1)	(500.0)
Net loss	70.1	(94.6)	(485.2)
Electricity, Purchased [Member]
Cost of revenues:
Cost of Goods and Services Sold	305.0	291.0	319.1
Electricity [Member]
Revenues	775.9	743.9	834.2
Cost of revenues:
Cost of Goods and Services Sold	322.5	300.0	336.5
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	738.7
Cost of revenues:
Net fuel cost	2.4	0.5	5.3
Gross margin	435.0	429.7	486.0
Utilities Operating Expense, Maintenance and Operations	139.7	156.5	178.4
Depreciation and amortization	74.5	75.3	71.0
Taxes, Miscellaneous	73.1	76.3	68.0
Fixed-asset impairment (Note 14)	0.0	66.3	1,353.5
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(0.2)	0.5	0.4
Gain (Loss) on Disposition of Business	(12.4)	0.0	0.0
Operating Expenses	299.9	307.6	317.0
Operating income	135.1	122.1	169.0
Other income / (expense), net
Interest expense	(27.3)	(30.5)	(24.7)
Charge for early redemption of debt	(0.6)	(1.1)	(0.5)
Other income	(2.8)	(2.0)	(0.2)
Other expense, net	(30.7)	(33.6)	(25.4)
Income / (loss) from continuing operations before income tax	104.4	88.5	143.6
Income tax expense / (benefit) from continuing operations	17.7	31.1	46.0
Net income / (loss) from continuing operations	86.7	57.4	97.6
Income / (loss) from discontinued operations before income tax	0.0	(56.3)	(1,338.7)
Income tax expense / (benefit) from discontinued operations	0.0	(15.9)	(468.4)
Net income / (loss) from discontinued operations	0.0	(40.4)	(870.3)
Dividends on preferred stock	0.0	0.0	0.7
Income / (loss) attributable to common stock	86.7	17.0	(773.4)
Net loss	86.7	17.0	(772.7)
THE DAYTON POWER AND LIGHT COMPANY [Member] | Electricity, Purchased [Member]
Cost of revenues:
Cost of Goods and Services Sold	301.3	289.8	316.7
THE DAYTON POWER AND LIGHT COMPANY [Member] | Electricity [Member]
Revenues	738.7	720.0	808.0
Cost of revenues:
Cost of Goods and Services Sold	$ 303.7	$ 290.3	$ 322.0