Commitments and Contingencies, Guarantees and Indemnifications (Details) (Payment or Performance Guarantee [Member], Customer Loans for Farm Rewiring Program [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Payment or Performance Guarantee [Member] | Customer Loans for Farm Rewiring Program [Member]
Guarantees [Abstract]
Guarantee issued and outstanding	$ 1.0	$ 1.0
Current exposure under the guarantee	$ 0.3	$ 0.4