Off-Balance Sheet Guarantees and Long Term Standby Purchase Commitments - Future Minimum Lease Payments and Other Contractual Obligations (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating Leases, Rent Expense, Net	$ 1,300,000	$ 1,300,000	$ 1,300,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	1,375,000
Operating Leases, Future Minimum Payments, Due in Two Years	1,378,000
Operating Leases, Future Minimum Payments, Due in Three Years	1,400,000
Operating Leases, Future Minimum Payments, Due in Four Years	1,388,000
Operating Leases, Future Minimum Payments, Due in Five Years	1,389,000
Operating Leases, Future Minimum Payments, Due Thereafter	6,951,000
Operating Leases, Future Minimum Payments Due	13,881,000
Contractual Obligation, Fiscal Year Maturity [Abstract]
Contractual Obligation, Due in Next Twelve Months	773,000
Contractual Obligation, Due in Second Year	209,000
Contractual Obligation, Due in Third Year	88,000
Contractual Obligation, Due in Fourth Year	0
Contractual Obligation, Due in Fifth Year	0
Contractual Obligation, Due after Fifth Year	0
Contractual Obligation	1,070,000
Farm & Ranch Loans and USDA Guarantees [Member]
Long-term Purchase Commitment [Line Items]
Loans and Leases Receivable, Commitments to Purchase or Sell	29,700,000	54,800,000
Rural Utilities Loans [Member]
Long-term Purchase Commitment [Line Items]
Loans and Leases Receivable, Commitments to Purchase or Sell	$ 4,000,000	$ 26,300,000