Business Segments (Narrative) (Details)	12 Months Ended
	Dec. 31, 2014 sqmi	Dec. 31, 2013 sqmi
Service area, square miles	6,000	6,000
Number of coal fired power plants	5	5
Approximate number of retail customers	516,000	516,000
Approximate Number Of Competitive Retail Customers	260,000
DP&L [Member]
Service area, square miles	6,000
Number of coal fired power plants	5
Approximate number of retail customers	516,000