Guarantees and Commitments - Reserve For Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Reserve for losses	$ 1,950	$ 3,277
Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	1,068	2,097	$ 2,164	$ 2,167
Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	882	1,180	$ 0	$ 0
LTSPCs and Farmer Mac Guaranteed Securities | Agricultural Finance
Guarantor Obligations [Line Items]
Reserve for losses	1,068	2,097
LTSPCs | Rural Infrastructure Finance
Guarantor Obligations [Line Items]
Reserve for losses	$ 882	$ 1,180