Shareholder's Equity (Details) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jan. 01, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Preferred Stock, Redemption Amount	$ 23,500,000
Accounts Payable, Related Parties, Current	$ 1,400,000			$ 500,000
Common stock, shares authorized	1,500			1,500
Common stock, shares outstanding	1			1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Preferred Stock, Redemption Amount	$ 23,500,000
Accounts Payable, Related Parties, Current	$ 1,400,000			$ 500,000
Common stock, shares authorized	250,000,000
Par value common shares (in USD per share)	$ 0.01			$ 0.01
Common stock, shares outstanding	41,172,173
PUCO merger equity ratio approval (at least)	50.00%
PUCO Equity Ratio	50.00%
PUCO merger, maximum long-term debt allowed	$ 750,000,000.0
PUCO merger, maximum long-term debt as percent of rate base (percent)	75.00%
Subsidiary of Common Parent [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Equity Settlement of Related Party Payable	$ 7,500,000	$ 0
Accounts Payable, Related Parties, Current			$ 7,500,000