Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended		22 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012
Dividend Reinvestment and Stock Purchase Plan
Authorized common shares to be issued	6,000,000
Number of common shares issued	55,598	59,605	115,203
Amount raised from shares issued	$ 2.2	$ 2.0	$ 4.2