Guarantees - Schedule of Underlying Off-Balance Sheet Guaranteed Securities (Details) - Farmer Mac Guaranteed Securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Guarantee and commitment obligation	$ 2,230	$ 2,804
Weighted-average remaining maturity	9 years 9 months 18 days	10 years 3 months 18 days
Institutional Credit
Guarantor Obligations [Line Items]
Weighted-average remaining maturity	5 years	5 years