Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ (51.7)	$ 31.8
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	0.2	0.2
Reclassification to earnings, net of income tax	(0.1)	(0.1)
Total change in fair value of available-for-sale securities	0.1	0.1
Derivative activity:
Change in derivative fair value, net of income tax	5.2	21.5
Reclassification of earnings, net of income tax	1.0	(8.2)
Total change in fair value of derivatives	6.2	13.3
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(0.3)	0.0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax	(1.2)	0.0
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.8	0.0
Total change in unfunded pension obligation	(0.7)	0.0
Other comprehensive income / (loss)	5.6	13.4
Net comprehensive income / (loss)	(46.1)	45.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income	(41.8)	33.7
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	0.2	0.2
Reclassification to earnings, net of income tax	(0.1)	(0.1)
Total change in fair value of available-for-sale securities	0.1	0.1
Derivative activity:
Change in derivative fair value, net of income tax	5.2	21.5
Reclassification of earnings, net of income tax	1.0	(8.4)
Total change in fair value of derivatives	6.2	13.1
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(1.1)	0.0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax	(0.5)	0.0
Pension and postretirement activity:
Reclassification to earnings, net of income tax	2.5	0.3
Total change in unfunded pension obligation	0.9	0.3
Other comprehensive income / (loss)	7.2	13.5
Net comprehensive income / (loss)	$ (34.6)	$ 47.2