Guarantees and Commitments - Off-Balance Sheet Guaranteed Securities (Details) - Unconsolidated VIE - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Total off-balance sheet Farmer Mac Guaranteed Securities	$ 581,113	$ 383,022
Agricultural Finance
Guarantor Obligations [Line Items]
Total off-balance sheet Farmer Mac Guaranteed Securities	578,358	378,610
Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Total off-balance sheet Farmer Mac Guaranteed Securities	$ 2,755	$ 4,412