Guarantees and Commitments - Reserve For Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Reserve for losses	$ 1,840	$ 1,950
Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	993	1,068	$ 1,366	$ 2,097
Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	847	882	$ 967	$ 1,180
LTSPCs and Farmer Mac Guaranteed Securities | Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	993	1,068
LTSPCs | Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	$ 847	$ 882