Business Segments (Narrative) (Details)	12 Months Ended
	Dec. 31, 2012 sqmi
Service area, counties	24
Service area, square miles	6,000
Number of coal fired power plants	8
Approximate number of retail customers	513,000
Approximate Number Of Competitive Retail Customers	198,000
Number of MC Squared Retail Customers	3,157
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	513,000