Loans - Unpaid Principal Balances by Delinquency Status (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	$ 8,915,656	$ 9,008,979
Nonaccrual loans	95,281	78,965
Total loans	10,657,047	10,549,845
Nonaccrual loans with no associated allowance	16,100	22,000
Interest received on nonaccrual loans	500	5,600
Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	6,306,079	6,362,326
Nonaccrual loans	82,026	63,402
Total loans	6,306,079	6,362,326
Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	1,172,864	1,166,253
Nonaccrual loans	13,255	15,563
Total loans	1,172,864	1,166,253
Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans	95,281	78,965
Total loans	7,478,943	7,528,579
Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	3,178,104	3,021,266
Nonaccrual loans	0	0
Total loans	3,178,104	3,021,266
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	10,548,452	10,459,282
Current | Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	6,210,739	6,287,326
Current | Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	1,159,609	1,150,690
Current | Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	7,370,348	7,438,016
Current | Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	3,178,104	3,021,266
Total Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	13,314	11,598
Total Past Due | Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	13,314	11,598
Total Past Due | Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
Total Past Due | Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	13,314	11,598
Total Past Due | Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
30-59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	4,403	10,066
30-59 Days | Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	4,403	10,066
30-59 Days | Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
30-59 Days | Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	4,403	10,066
30-59 Days | Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
60-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	1,989	392
60-89 Days | Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	1,989	392
60-89 Days | Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
60-89 Days | Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	1,989	392
60-89 Days | Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
90 Days and Greater
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	6,922	1,140
90 Days and Greater | Farm & Ranch
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	6,922	1,140
90 Days and Greater | Corporate AgFinance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	0	0
90 Days and Greater | Agricultural Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	6,922	1,140
90 Days and Greater | Rural Infrastructure Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment, at amortized cost	$ 0	$ 0