Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Unrecognized tax benefits due to uncertainty in timing of deductibility	$ 0.9
Tax Refund		$ 19.9
Decrease in income tax expense		$ 1.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income Taxes [Line Items]
Unrecognized tax benefits due to uncertainty in timing of deductibility	0.9
Tax Refund	19.9
Decrease in income tax expense	$ 1.2