Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	$ 0.0	$ (0.3)	$ (0.1)	$ 0.0
Income tax (expense) benefit on reclassification to earnings	0.0	(0.2)	0.0	0.0
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	4.7	(1.0)	(7.1)	(1.0)
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	5.9	0.9	10.7	0.5
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	0.0	(0.5)	(0.2)	(0.4)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	0.0	0.2	(0.1)	0.0
Income tax (expense) benefit on reclassification to earnings	0.0	(0.2)	0.0	0.0
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	4.7	(1.0)	(7.0)	(1.0)
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	5.9	1.0	10.5	0.7
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	$ (0.4)	$ (0.5)	$ (1.2)	$ (1.0)