Loans and Allowance for Losses and Concentrations of Credit Risk Narrative (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan Losses Expensed	$ (529,000)		$ (1,220,000)	$ (99,000)		$ (800,000)
Financing Receivable, Allowance for Credit Losses	13,478,000		18,140,000	13,478,000		18,140,000	14,252,000	16,890,000	17,966,000	17,516,000
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	90 days
Provision for Other Credit Losses	(175,000)		1,394,000	571,000		1,424,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,490,000			2,490,000				6,659,000
Alternate minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	120 days
Eligible Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan Losses Expensed	(529,000)		(1,220,000)	(99,000)		(800,000)
Allowance for Loan and Lease Losses, Write-offs	70,000		0	3,884,000		0
Long-Term Standby Purchase Commitments and Farmer Mac Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Other Credit Losses	(175,000)		1,394,000	571,000		1,424,000
Long-Term Standby Purchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	0		2,530,000	37,000		2,530,000
Farm & Ranch Guaranteed Securities [Member] | Long-Term Standby Purchase Commitments and Farmer Mac Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities, Number Defaulted	6			8
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	5,935,000		3,128,000	6,075,000		3,857,000
Farm & Ranch Guaranteed Securities [Member] | Long-Term Standby Purchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities, Number Defaulted			4			5
Financing Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment, During the Period	700,000		100,000	900,000		1,100,000
Financing Receivable, Modifications, Post-Modification Recorded Investment, During the Period	700,000		100,000	1,000,000		1,300,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2			2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	400,000			400,000
Collateral Dependent Not Individually Analyzed [Member] | Financing Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan, Lease, and Other Losses	$ 100,000	[1]		$ 100,000	[1]

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $53.4 million (56 percent) of impaired loans as of June 30, 2013, which resulted in a specific reserve of $1.1 million.