LOANS - Schedule of Composition of Loan Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	$ 12,652,618		$ 11,360,197
Allowance for losses	(19,951)		(16,031)
Total loans, net of allowance	12,367,333		11,039,349
Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	12,652,618		11,360,197
Unamortized premiums, discounts, fair value hedge basis adjustment, and other cost basis adjustments	(265,334)		(304,817)
Total loans	12,387,284		11,055,380
Allowance for losses	(19,951)		(16,031)
Total loans, net of allowance	12,367,333		11,039,349
Agricultural Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	8,269,263		7,825,434
Allowance for losses	(10,601)	$ (8,690)	(6,884)	$ (7,588)	$ (11,302)	$ (6,775)
Agricultural Finance | Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	8,269,263		7,825,434
Allowance for losses	(10,601)		(6,884)
Farm & Ranch
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	6,971,700		6,565,711
Allowance for losses	(4,832)	(4,676)	(3,936)	(3,910)	(3,935)	(4,044)
Farm & Ranch | Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	6,971,700		6,565,711
Allowance for losses	(4,832)		(3,936)
Corporate AgFinance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,297,563		1,259,723
Allowance for losses	(5,769)	(4,014)	(2,948)	(3,678)	(7,367)	(2,731)
Corporate AgFinance | Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,297,563		1,259,723
Allowance for losses	(5,769)		(2,948)
Rural Infrastructure Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	4,383,355		3,534,763
Allowance for losses	(9,350)	$ (7,810)	(9,147)	$ (9,026)	$ (5,446)	$ (8,314)
Rural Infrastructure Finance | Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	4,383,355		3,534,763
Allowance for losses	(9,350)		(9,147)
Unsecuritized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	10,934,178		9,927,936
Unamortized premiums, discounts, fair value hedge basis adjustment, and other cost basis adjustments	(265,334)		(304,817)
Total loans	10,668,844		9,623,119
Allowance for losses	(19,314)		(15,588)
Total loans, net of allowance	10,649,530		9,607,531
Unsecuritized | Agricultural Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	6,550,823		6,393,173
Unsecuritized | Farm & Ranch
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	5,253,260		5,133,450
Unsecuritized | Corporate AgFinance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,297,563		1,259,723
Unsecuritized | Rural Infrastructure Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	4,383,355		3,534,763
In Consolidated Trusts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,718,440		1,432,261
Unamortized premiums, discounts, fair value hedge basis adjustment, and other cost basis adjustments	0		0
Total loans	1,718,440		1,432,261
Allowance for losses	(637)		(443)
Total loans, net of allowance	1,717,803		1,431,818
In Consolidated Trusts | Agricultural Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,718,440		1,432,261
In Consolidated Trusts | Farm & Ranch
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	1,718,440		1,432,261
In Consolidated Trusts | Corporate AgFinance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	0		0
In Consolidated Trusts | Rural Infrastructure Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	$ 0		$ 0