Guarantees and Commitments - Changes in Reserve for Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 3,277
Provision for losses	(1,327)	$ 250	$ (3)
Ending balance	1,950	3,277
Agricultural Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	2,097	2,164	2,167
Provision for losses	(1,029)	81	(3)
Ending balance	1,068	2,097	2,164
Agricultural Finance | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		(148)
Ending balance			(148)
Agricultural Finance | Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		2,016
Ending balance			2,016
Rural Infrastructure Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	1,180	0	0
Provision for losses	(298)	169	0
Ending balance	$ 882	1,180	0
Rural Infrastructure Finance | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		1,011
Ending balance			1,011
Rural Infrastructure Finance | Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		$ 1,011
Ending balance			$ 1,011