Consolidated Statements of Comprehensive Income/(Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 33.2	$ (1,810.9)	$ 76.0	$ (1,777.3)
Available-for-sale securities activity:
Change in fair value of available-for-sale securities	0.2	0.2	(1.3)	0.5
Reclassification to earnings of available-for-sale securities, net of income tax expense/(benefit)	0.4		1.4
Total change in fair value of available-for-sale securities	0.6	0.2	0.1	0.5
Derivative activity:
Change in derivative fair value	6.2	0.3	18.7	(5.5)
Reclassification of earnings of Cash Flow Hedge	1.3		3.0	(0.8)
Total change in fair value of derivatives	7.5	0.3	21.7	(6.3)
Pension and postretirement activity:
Reclassification to earnings of Pension			0.3	(0.1)
Total change in unfunded pension obligation			0.3	(0.1)
Other comprehensive income / (loss)	8.1	0.5	22.1	(5.9)
Net comprehensive income / (loss)	41.3	(1,810.4)	98.1	(1,783.2)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income	40.9	(11.2)	101.4	58.3
Available-for-sale securities activity:
Change in fair value of available-for-sale securities	(0.2)	0.2	(1.8)	0.5
Reclassification to earnings of available-for-sale securities, net of income tax expense/(benefit)	0.4		1.4
Total change in fair value of available-for-sale securities	0.2	0.2	(0.4)	0.5
Derivative activity:
Change in derivative fair value	(0.3)	(2.5)		(4.0)
Reclassification of earnings of Cash Flow Hedge	1.0	(0.7)	2.3	(3.1)
Total change in fair value of derivatives	0.7	(3.2)	2.3	(7.1)
Pension and postretirement activity:
Reclassification to earnings of Pension	0.9	1.0	2.7	3.0
Total change in unfunded pension obligation	0.9	1.0	2.7	3.0
Other comprehensive income / (loss)	1.8	(2.0)	4.6	(3.6)
Net comprehensive income / (loss)	$ 42.7	$ (13.2)	$ 106.0	$ 54.7