Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Sales to related party	$ 1.2	$ 1.3
Charges for services provided	11.6	9.8
Net advance to / (payable to) to the Service Company			$ (0.5)
Net advance to / (payable to) to the Service Company	0.8
Short-term loan with DPL	5.0		35.0
Investment in trust	0.3		0.3
Income tax receivable	0.8
Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]
Related Party Transaction [Line Items]
Note payable to trust	15.6		15.6
Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Net advance to / (payable to) to the Service Company	78.9		50.5
Income tax receivable	78.9		50.5
Charges for health, welfare and benefit plans [Member] | AES affiliates [Member]
Related Party Transaction [Line Items]
Transactions with other AES affiliates	4.1	4.0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Related Party Transaction [Line Items]
Sales to related party	1.2	1.3
Premiums paid for insurance services provided by MVIC	(0.9)	(0.8)
Expense recoveries for services provided to DPLER	0.0	0.7
Charges for services provided	8.9	8.4
Net advance to / (payable to) to the Service Company			(0.5)
Net advance to / (payable to) to the Service Company	0.8
Income tax receivable	0.8
Gain on termination of contract	27.7
THE DAYTON POWER AND LIGHT COMPANY [Member] | Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Net advance to / (payable to) to the Service Company	13.2		1.5
Income tax receivable	13.2		$ 1.5
THE DAYTON POWER AND LIGHT COMPANY [Member] | Charges for health, welfare and benefit plans [Member] | AES affiliates [Member]
Related Party Transaction [Line Items]
Transactions with other AES affiliates	4.1	3.9
THE DAYTON POWER AND LIGHT COMPANY [Member] | Dpler [Member]
Related Party Transaction [Line Items]
Sales to related party	$ 0.0	$ 110.7