Dispositions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 24.1	$ 31.9	$ (6.5)
Payments for Removal Costs	51.0	14.5	0.0
Beckjord [Member]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(11.7)
Payments for Removal Costs		14.5
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	124.3	104.4	88.5
Payments for Removal Costs	$ 0.0	14.5	$ 0.0
THE DAYTON POWER AND LIGHT COMPANY [Member] | Beckjord [Member]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(12.4)
Payments for Removal Costs		$ (14.5)