Guarantees and Commitments - Reserve For Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Reserve for losses	$ 1,510		$ 1,950
Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	743	$ 882	1,068	$ 1,103	$ 1,194	$ 2,097
Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	767	$ 795	882	$ 897	$ 917	$ 1,180
LTSPCs and Farmer Mac Guaranteed Securities | Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	743		1,068
LTSPCs | Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	$ 767		$ 882