FAIR VALUE DISCLOSURES - Schedule of Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Assets:
Financial derivatives	$ 32,667	$ 27,789
Liabilities:
Financial derivatives	29,161	77,326
Investment securities
Assets:
Available-for-sale, at fair value	6,655,946	5,953,014
Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	$ 5,854,098	$ 5,514,546
Level 3
Liabilities:
Percent of level three fair value assets and liabilities	18.00%	18.00%
Financial instruments level three percent	47.00%	48.00%
Recurring
Assets:
Loans		$ 6,160
Financial derivatives	$ 32,667	27,789
Guarantee Asset	5,049	5,382
Total Assets at fair value	12,548,216	11,507,709
Liabilities:
Financial derivatives	29,161	77,326
Total Liabilities at fair value	29,161	77,326
Recurring | USDA Securities
Assets:
Trading	456	818
Recurring | Investment securities
Assets:
Available-for-sale, at fair value	6,655,946	5,953,014
Recurring | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	5,854,098	5,514,546
Recurring | Level 1
Assets:
Loans		0
Financial derivatives	202	47
Guarantee Asset	0	0
Total Assets at fair value	1,476,695	1,289,893
Liabilities:
Financial derivatives	11	0
Total Liabilities at fair value	11	0
Recurring | Level 1 | USDA Securities
Assets:
Trading	0	0
Recurring | Level 1 | Investment securities
Assets:
Available-for-sale, at fair value	1,476,493	1,289,846
Recurring | Level 1 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
Recurring | Level 2
Assets:
Loans		6,160
Financial derivatives	32,465	27,742
Guarantee Asset	0	0
Total Assets at fair value	5,192,436	4,677,594
Liabilities:
Financial derivatives	29,150	77,326
Total Liabilities at fair value	29,150	77,326
Recurring | Level 2 | USDA Securities
Assets:
Trading	0	0
Recurring | Level 2 | Investment securities
Assets:
Available-for-sale, at fair value	5,159,971	4,643,692
Recurring | Level 2 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
Recurring | Level 3
Assets:
Loans		0
Financial derivatives	0	0
Guarantee Asset	5,049	5,382
Total Assets at fair value	5,879,085	5,540,222
Liabilities:
Financial derivatives	0	0
Total Liabilities at fair value	0	0
Recurring | Level 3 | USDA Securities
Assets:
Trading	456	818
Recurring | Level 3 | Investment securities
Assets:
Available-for-sale, at fair value	19,482	19,476
Recurring | Level 3 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	5,854,098	5,514,546
AgVantage | Recurring | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	5,845,642	5,505,531
AgVantage | Recurring | Level 1 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
AgVantage | Recurring | Level 2 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
AgVantage | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	5,845,642	5,505,531
Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	8,456	9,015
Farmer Mac Guaranteed USDA Securities | Recurring | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	8,456	9,015
Farmer Mac Guaranteed USDA Securities | Recurring | Level 1 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
Farmer Mac Guaranteed USDA Securities | Recurring | Level 2 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	0	0
Farmer Mac Guaranteed USDA Securities | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Assets:
Available-for-sale, at fair value	8,456	9,015
USDA Securities | Recurring | USDA Securities
Assets:
Trading	456	818
USDA Securities | Recurring | Level 1 | USDA Securities
Assets:
Trading	0	0
USDA Securities | Recurring | Level 2 | USDA Securities
Assets:
Trading	0	0
USDA Securities | Recurring | Level 3 | USDA Securities
Assets:
Trading	456	818
Floating interest rate | Floating rate auction-rate certificates backed by Government guaranteed student loans
Assets:
Available-for-sale, at fair value	19,482	19,476
Floating interest rate | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,313,850	2,305,725
Floating interest rate | Recurring | Floating rate auction-rate certificates backed by Government guaranteed student loans
Assets:
Available-for-sale, at fair value	19,482	19,476
Floating interest rate | Recurring | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,313,850	2,305,725
Floating interest rate | Recurring | Level 1 | Floating rate auction-rate certificates backed by Government guaranteed student loans
Assets:
Available-for-sale, at fair value	0	0
Floating interest rate | Recurring | Level 1 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	0	0
Floating interest rate | Recurring | Level 2 | Floating rate auction-rate certificates backed by Government guaranteed student loans
Assets:
Available-for-sale, at fair value	0	0
Floating interest rate | Recurring | Level 2 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,313,850	2,305,725
Floating interest rate | Recurring | Level 3 | Floating rate auction-rate certificates backed by Government guaranteed student loans
Assets:
Available-for-sale, at fair value	19,482	19,476
Floating interest rate | Recurring | Level 3 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	0	0
Fixed Interest Rate | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,846,121	2,337,967
Fixed Interest Rate | Fixed rate U.S. Treasuries
Assets:
Available-for-sale, at fair value	1,476,493	1,289,846
Fixed Interest Rate | Recurring | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,846,121	2,337,967
Fixed Interest Rate | Recurring | Fixed rate U.S. Treasuries
Assets:
Available-for-sale, at fair value	1,476,493	1,289,846
Fixed Interest Rate | Recurring | Level 1 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	0	0
Fixed Interest Rate | Recurring | Level 1 | Fixed rate U.S. Treasuries
Assets:
Available-for-sale, at fair value	1,476,493	1,289,846
Fixed Interest Rate | Recurring | Level 2 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	2,846,121	2,337,967
Fixed Interest Rate | Recurring | Level 2 | Fixed rate U.S. Treasuries
Assets:
Available-for-sale, at fair value	0	0
Fixed Interest Rate | Recurring | Level 3 | Guaranteed mortgage-backed securities
Assets:
Available-for-sale, at fair value	0	0
Fixed Interest Rate | Recurring | Level 3 | Fixed rate U.S. Treasuries
Assets:
Available-for-sale, at fair value	$ 0	$ 0