Business Segments (Narrative) (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Service area, counties		24
Service area, square miles		6,000
Number of coal fired power plants	8	8
Approximate number of retail customers		500,000
Competitive Retail [Member]
Approximate number of retail customers	3,000	25,000