Business Segments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015 sqmi
Service area, square miles	6,000
Number of coal fired power plants	5
Approximate number of retail customers	516,000
Approximate Number Of Competitive Retail Customers	259,000
Number of MC Squared Retail Customers	116,000
DP&L [Member]
Service area, square miles	6,000
Approximate number of retail customers	516,000