Loans and Allowance for Losses and Concentrations of Credit Risk Loan (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 2,711,796	[1]	$ 2,864,132	[1]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	35,272		40,185
Lower of Cost or Fair Value Adjustment on Loans Held for Sale	(5,943)		0
Loans Held for Investment and Loans in Consolidated Trusts, at Amortized Cost	2,067,134		2,362,870
Loans held for sale, at lower of cost or fair value	673,991		541,447
Loans and Leases Receivable, Net of Deferred Income	2,741,125		2,904,317
Allowance for Loan and Lease Losses, Real Estate	(11,351)		(10,161)
Total loans, net of allowance	2,729,774		2,894,156
Farmer Mac I [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,679,851		1,948,105
Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,031,945		916,027
Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	529,284	[1]	1,083,535	[1]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	34,291		38,024
Lower of Cost or Fair Value Adjustment on Loans Held for Sale	0		0
Loans Held for Investment and Loans in Consolidated Trusts, at Amortized Cost	563,575		1,121,559
Loans held for sale, at lower of cost or fair value	0		0
Loans and Leases Receivable, Net of Deferred Income	563,575		1,121,559
Allowance for Loan and Lease Losses, Real Estate	(365)		(740)
Total loans, net of allowance	563,210		1,120,819
Variable Interest Entity, Primary Beneficiary [Member] | Farmer Mac I [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	160,436		696,735
Variable Interest Entity, Primary Beneficiary [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	368,848		386,800
Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	2,182,512	[1]	1,780,597	[1]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	981		2,161
Lower of Cost or Fair Value Adjustment on Loans Held for Sale	(5,943)		0
Loans Held for Investment and Loans in Consolidated Trusts, at Amortized Cost	1,503,559		1,241,311
Loans held for sale, at lower of cost or fair value	673,991		541,447
Loans and Leases Receivable, Net of Deferred Income	2,177,550		1,782,758
Allowance for Loan and Lease Losses, Real Estate	(10,986)		(9,421)
Total loans, net of allowance	2,166,564		1,773,337
Unsecuritized [Member] | Farmer Mac I [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,519,415		1,251,370
Unsecuritized [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 663,097		$ 529,227

[1] Unpaid principal balance is the basis of presentation in disclosures of outstanding balances for Farmer Mac's lines of business.