Common Equity Automatic Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Equity [Abstract]
Stock Issued During Period, Shares, Dividend Reinvestment Plan and Stock Purchase Plan	69,986	215,832
Proceeds From Issuance of Shares Under Dividend Reinvestment Plan And Stock Purchase Plan	$ 3.4	$ 10.6
Shares Held in Reserve Related to Dividend Reinvestment Plan and Stock Purchase Plan	2,430,456	2,430,456