Loans - Changes in the Allowance for Losses (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance			$ 14,041,000
Provision for/(release of) losses	$ 617,000	$ 366,000	(699,000)	$ 518,000
Ending balance	13,002,000		13,002,000
Agricultural Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	4,015,000	3,092,000	3,442,000	3,745,000
Provision for/(release of) losses	181,000	414,000	838,000	(239,000)
Charge-offs	0	0	(84,000)	0
Ending balance	4,196,000	3,506,000	4,196,000	3,506,000
Agricultural Finance | Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Provision for/(release of) losses			1,700,000	1,800,000
Rural Infrastructure Finance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	8,388,000	10,908,000	10,599,000	10,087,000
Provision for/(release of) losses	418,000	(120,000)	(1,793,000)	701,000
Charge-offs	0	0	0	0
Ending balance	$ 8,806,000	$ 10,788,000	8,806,000	10,788,000
Rural Infrastructure Finance | Collateral Pledged
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Provision for/(release of) losses			$ 0	$ 0