Common Equity Automatic Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Equity [Abstract]
Stock Issued During Period, Shares, Dividend Reinvestment Plan and Stock Purchase Plan	277,245
Proceeds From Issuance of Shares Under Dividend Reinvestment Plan And Stock Purchase Plan	$ 13.8
Shares Held in Reserve Related to Dividend Reinvestment Plan and Stock Purchase Plan	2,369,043