Benefit Plans (Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Income)) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.02%	4.86%	4.04%
Expected rate of return on plan assets	6.50%	6.75%	6.75%
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	4.02%	4.86%	4.04%
Expected rate of return on plan assets	6.50%	6.75%	6.75%
Rate of compensation increases	3.94%	3.94%	3.94%
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.81%	4.51%	4.58%
Expected rate of return on plan assets	4.50%	6.00%	6.00%
Postretirement [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.81%	4.51%	4.58%
Expected rate of return on plan assets	4.50%	6.00%	6.00%