Guarantees and Commitments - Reserve For Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Reserve for losses	$ 1,677		$ 1,950
Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	882	$ 993	1,068	$ 1,194	$ 1,366	$ 2,097
Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	795	$ 847	882	$ 917	$ 967	$ 1,180
LTSPCs and Farmer Mac Guaranteed Securities | Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	882		1,068
LTSPCs | Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	$ 795		$ 882