Business Segments (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Service area, counties	24
Service area, square miles	6,000
Number of coal fired power plants	8
Approximate number of retail customers	500,000
Approximate Number Of Competitive Retail Customers	175,000
Number of MC Squared Retail Customers	$ 101,000
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	500,000