Loans - Changes in the Allowance for Losses (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance			$ 14,041,000
Release of/(provision for) losses	$ (1,372,000)	$ (761,000)	(1,316,000)	$ 152,000
Ending balance	12,403,000		12,403,000
Agricultural Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	3,948,000	3,718,000	3,442,000	3,745,000
Release of/(provision for) losses	67,000	(626,000)	657,000	(653,000)
Charge-offs	0	0	(84,000)	0
Ending balance	4,015,000	3,092,000	4,015,000	3,092,000
Agricultural Finance | Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Release of/(provision for) losses			1,200,000	1,800,000
Rural Infrastructure Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	9,622,000	11,089,000	10,599,000	10,087,000
Release of/(provision for) losses	(1,234,000)	(181,000)	(2,211,000)	821,000
Charge-offs	0	0	0	0
Ending balance	$ 8,388,000	$ 10,908,000	8,388,000	10,908,000
Rural Infrastructure Finance | Collateral Pledged
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Release of/(provision for) losses			$ 0	$ 0