Business Segments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2013 sqmi
Service area, counties	24
Service area, square miles	6,000
Number of coal fired power plants	8
Approximate number of retail customers	514,000
Approximate Number Of Competitive Retail Customers	247,000
Number of MC Squared Retail Customers	137,000
DP&L [Member]
Service area, counties	24
Service area, square miles	6,000
Number of coal fired power plants	8
Approximate number of retail customers	514,000