Loans and Allowance for Losses and Concentrations of Credit Risk Certain Loans Acquired in Transfer (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$ 41,737	$ 35,773	$ 34,473
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Other-than-Temporary Impairment Charges, During the Period	4,774	3,845	1,736
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	997	714	3,005
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	33,798	29,461	30,365
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	8,091	14,192	2,626
Long-Term Standby Purchase Commitments [Member] \| Farmer Mac I Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities, Number Defaulted		20	22
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period		21,663	6,082
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition, During the Period	17,432	21,715	6,200
Long-Term Standby Purchase Commitments and Farmer Mac Guaranteed Securities [Member] \| Farmer Mac I Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities, Number Defaulted	15
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Balance During Period	17,024
Farmer Mac Guaranteed Securities [Member] \| Farmer Mac I 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	$ 8,933	$ 7,471	$ 3,456

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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