Loans and Allowance for Losses and Concentrations of Credit Risk - Certain Loans Acquired Delinquencies and Net Credit Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	[2]	$ 32,136	[1]	$ 18,917	[3]
Net credit losses (recoveries)		3,853		(6)		$ 2,975
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities, Subject To Be Purchased	[2]	0		1,800
On-balance sheet [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	[2]	26,935	[1]	18,427	[3]
Net credit losses (recoveries)		3,853		(6)		2,975
Off-balance sheet [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	[2]	5,201	[1]	490	[3]
Net credit losses (recoveries)		$ 0		$ 0		$ 0

[1] Amounts represent unpaid principal balance of risk-rated loans, which is the basis Farmer Mac uses to analyze its portfolio, and recorded investment of past due loans.

[2] Includes loans and loans underlying off-balance sheet Farm & Ranch Guaranteed Securities and LTSPCs that are 90 days or more past due, in foreclosure, or in bankruptcy, excluding loans performing under either their original loan terms or a court-approved bankruptcy plan.

[3] Amounts represent unpaid principal balance of risk-rated loans, which is the basis Farmer Mac uses to analyze its portfolio, and recorded investment of past due loans.