Business Segments (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013 sqmi
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	281,000
Number of MC Squared Retail Customers	131,000
DP&L [Member]
Approximate number of retail customers	513,000