Benefit Plans (Weighted Average Assumptions Used to Determine Benefit Obligations) (Details)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.49%	4.02%	4.86%
Rate of compensation increases	3.94%	3.94%	3.94%
Pension [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.49%	4.02%	4.86%
Rate of compensation increases	3.94%	3.94%	3.94%
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.10%	3.71%	4.58%
Postretirement [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for obligations	4.10%	3.71%	4.58%