Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended	19 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Dividend Reinvestment and Stock Purchase Plan
Authorized common shares to be issued	6,000,000
Number of common shares issued	55,598	38,643	115,203
Amount raised from shares issued	$ 2.2	$ 1.3	$ 4.2

Amount of cash inflow from capital contributions to an entity associated with a dividend reinvestment plan and stock purchase plan.

No definition available.

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