Dividend Reinvestment and Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended	28 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Dividend Reinvestment and Stock Purchase Plan
Authorized common shares to be issued	6,000,000
Number of common shares issued	44,549	41,513	159,752
Amount raised from shares issued	$ 2.0	$ 1.6	$ 6.2

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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