Consolidated Statements of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues	$ 1,236.9	$ 1,427.3	$ 1,612.8
Cost of revenues:
Net fuel cost	210.3	268.8	259.8
Net purchased power cost	339.2	417.4	562.6
Total cost of revenues	549.5	686.2	822.4
Gross margin	687.4	741.1	790.4
Operating expenses:
Operation and maintenance	327.6	348.1	361.3
Depreciation and amortization	106.9	132.3	134.6
General taxes	89.7	85.7	87.0
Goodwill impairment (Note 7)	0.0	0.0	317.0
Fixed-asset impairment (Note 15)	175.8	859.0	0.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(6.6)	(0.1)	0.4
Total operating expenses	693.4	1,425.0	900.3
Operating loss	(6.0)	(683.9)	(109.9)
Other income / (expense), net
Investment income	0.3	0.4	0.2
Interest expense	(110.1)	(107.7)	(119.8)
Charge for early redemption of debt	(3.3)	(3.1)	(2.1)
Other income / (expense)	(0.8)	1.0	0.2
Other expense, net	(113.9)	(109.4)	(121.5)
Loss from continuing operations before income tax	(119.9)	(793.3)	(231.4)
Income tax expense / (benefit) from continuing operations	(25.3)	(278.8)	20.0
Net loss from continuing operations	(94.6)	(514.5)	(251.4)
Income / (loss) from discontinued operations	0.0	(0.7)	11.4
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0.0	49.2	0.0
Income tax expense / (benefit) from discontinued operations	0.0	19.2	(1.0)
Net income from discontinued operations	0.0	29.3	12.4
Net loss	(94.6)	(485.2)	(239.0)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	720.0	808.0	857.0
Cost of revenues:
Net fuel cost	0.5	5.3	(9.0)
Net purchased power cost	289.8	316.7	317.4
Total cost of revenues	290.3	322.0	308.4
Gross margin	429.7	486.0	548.6
Operating expenses:
Operation and maintenance	158.0	179.3	184.0
Depreciation and amortization	75.3	71.0	71.5
General taxes	76.3	68.0	70.8
Fixed-asset impairment (Note 15)	66.3	1,353.5	0.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(0.5)	(0.4)	0.1
Total operating expenses	309.1	317.9	326.4
Operating loss	120.6	168.1	222.2
Other income / (expense), net
Investment income	0.3	0.4	0.3
Interest expense	(30.5)	(24.7)	(28.9)
Charge for early redemption of debt	(1.1)	(0.5)	(4.8)
Other income / (expense)	(0.8)	0.3	0.2
Other expense, net	(32.1)	(24.5)	(33.2)
Loss from continuing operations before income tax	88.5	143.6	189.0
Income tax expense / (benefit) from continuing operations	31.1	46.0	59.0
Net loss from continuing operations	57.4	97.6	130.0
Income / (loss) from discontinued operations	(56.3)	(1,338.7)	(47.5)
Income tax expense / (benefit) from discontinued operations	(15.9)	(468.4)	(23.9)
Net income from discontinued operations	(40.4)	(870.3)	(23.6)
Dividends on preferred stock	0.0	0.7	0.9
Income / (loss) attributable to common stock	17.0	(773.4)	105.5
Net loss	$ 17.0	$ (772.7)	$ 106.4