Consolidated Statements of Comprehensive Income/(Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net income	$ 19.9	$ 21.7
Available-for-sale securities activity:
Change in fair value of available-for-sale securities	0.2	0.4
Reclassification to earnings of available-for-sale securities, net of income tax expense/(benefit)	0.1
Total change in fair value of available-for-sale securities	0.3	0.4
Derivative activity:
Change in derivative fair value	1.2	7.6
Reclassification of earnings of Cash Flow Hedge	0.2	(0.9)
Total change in fair value of derivatives	1.4	6.7
Pension and postretirement activity:
Reclassification to earnings of Pension	0.3
Total change in unfunded pension obligation	0.3
Other comprehensive income / (loss)	2.0	7.1
Net comprehensive income / (loss)	21.9	28.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income	30.2	38.1
Available-for-sale securities activity:
Change in fair value of available-for-sale securities	0.2	0.4
Reclassification to earnings of available-for-sale securities, net of income tax expense/(benefit)	0.1
Total change in fair value of available-for-sale securities	0.3	0.4
Derivative activity:
Change in derivative fair value	(2.6)	(1.5)
Reclassification of earnings of Cash Flow Hedge	(0.2)	(1.7)
Total change in fair value of derivatives	(2.8)	(3.2)
Pension and postretirement activity:
Prior service cost for the period	0.9
Reclassification to earnings of Pension		1.1
Total change in unfunded pension obligation	0.9	1.1
Other comprehensive income / (loss)	(1.6)	(1.7)
Net comprehensive income / (loss)	$ 28.6	$ 36.4