Guarantees - Schedule of Underlying Off-Balance Sheet Guaranteed Securities (Details) - Farmer Mac Guaranteed Securities - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Guarantee and commitment obligation	$ 1,890	$ 2,230
Weighted-average remaining maturity	9 years 7 months 6 days	9 years 9 months 18 days
Institutional Credit
Guarantor Obligations [Line Items]
Weighted-average remaining maturity	4 years 6 months	5 years