Loans and Allowance for Losses and Concentrations of Credit Risk - Certain Loans Acquired in Transfer (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, impaired, loans past due period, minimum			90 days
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Provision for Loan Losses	$ 17	$ 61	$ 69	$ 447
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	5	839	7	889
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	30,463		30,463		32,838
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	28,429		28,429		29,613
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			1
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	0	0	440	37
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition, During the Period	0	6,086	440	6,229
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	0	6		8
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	0	5,935	440	6,075
Farmer Mac Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	$ 0	$ 5,935	$ 0	$ 6,038