Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	9 Months Ended		42 Months Ended
	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014
Dividend Reinvestment and Stock Purchase Plan
Authorized common shares to be issued		6,000,000
Number of common shares issued	1,135,897	1,290,872	89,975	2,855,214
Amount raised from shares issued	$ 50.0	$ 56.6	$ 3.9	$ 116.7