Loans and Allowance for Losses and Concentrations of Credit Risk - Loan (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	$ 3,250,204	[1]	$ 3,187,718	[1]
Unamortized premiums, discounts and other cost basis adjustments	974		12,396
Total loans	3,251,178		3,200,114
Allowance for Loan Losses	(7,410)		(6,866)
Total loans, net of allowance	3,243,768		3,193,248
Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	605,098	[1]	613,750	[1]
Unamortized premiums, discounts and other cost basis adjustments	4,366		16,239
Total loans	609,464		629,989
Allowance for Loan Losses	(451)		(279)
Total loans, net of allowance	609,013		629,710
Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	2,645,106	[1]	2,573,968	[1]
Unamortized premiums, discounts and other cost basis adjustments	(3,392)		(3,843)
Total loans	2,641,714		2,570,125
Allowance for Loan Losses	(6,959)		(6,587)
Total loans, net of allowance	2,634,755		2,563,538
Eligible Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Loan Losses	(7,410)		(6,866)		(7,967)	(11,351)
Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	2,222,958		2,135,467
Farm & Ranch [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	312,569		259,509
Farm & Ranch [Member] | Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	1,910,389		1,875,958
Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	1,027,246		1,052,251
Rural Utilities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	292,529		354,241
Rural Utilities [Member] | Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, Gross	$ 734,717		$ 698,010

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