Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 21.9	$ 15.1	$ (29.3)	$ (89.9)
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	0.1	0.1	0.4	0.2
Reclassification to earnings, net of income tax	0.0	0.0	(0.1)	0.0
Total change in fair value of available-for-sale securities	0.1	0.1	0.3	0.2
Derivative activity:
Change in derivative fair value, net of income tax	1.4	9.5	12.1	22.4
Reclassification of earnings, net of income tax	(2.4)	(5.5)	(6.0)	(24.4)
Total change in fair value of derivatives	(1.0)	4.0	6.1	(2.0)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0.0	0.0	(0.3)	0.0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	0.0	0.0	(1.2)	0.0
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.0	0.0	0.9	0.1
Total change in unfunded pension obligation	0.0	0.0	(0.6)	0.1
Other comprehensive income / (loss)	(0.9)	4.1	5.8	(1.7)
Net comprehensive income / (loss)	21.0	19.2	(23.5)	(91.6)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income	29.3	30.1	3.6	(467.8)
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	0.1	0.1	0.4	0.2
Reclassification to earnings, net of income tax	0.0	0.0	(0.1)	0.0
Total change in fair value of available-for-sale securities	0.1	0.1	0.3	0.2
Derivative activity:
Change in derivative fair value, net of income tax	1.4	9.5	12.1	22.5
Reclassification of earnings, net of income tax	(2.4)	(5.6)	(6.0)	(24.8)
Total change in fair value of derivatives	(1.0)	3.9	6.1	(2.3)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0.0	0.0	(1.1)	0.0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	0.0	0.0	(0.5)	0.0
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.7	0.7	3.8	1.7
Total change in unfunded pension obligation	0.7	0.7	2.2	1.7
Other comprehensive income / (loss)	(0.2)	4.7	8.6	(0.4)
Net comprehensive income / (loss)	$ 29.1	$ 34.8	$ 12.2	$ (468.2)