FAIR VALUE DISCLOSURES - Schedule of Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Assets:
Fair  Value	$ 13,580,285	$ 11,467,560
Loans		6,160
Financial derivatives	44,875	27,789
Other Assets	4,897	5,382
Total Assets at fair value	13,630,057	11,506,891
Liabilities:
Financial derivatives	21,618	77,326
Total Liabilities at fair value	21,618	77,326
Investment securities
Assets:
Fair  Value	13,580,285	11,467,560
Auction-rate certificates backed by Government guaranteed student loans
Assets:
Fair  Value		19,476
Government/GSE guaranteed mortgage-backed securities
Assets:
Fair  Value	5,297,018	4,643,692
U.S. Treasuries
Assets:
Fair  Value	1,544,147	1,289,846
AgVantage
Assets:
Fair  Value	6,730,917	5,505,531
Interest-Only Farmer Mac Guaranteed Securities
Assets:
Fair  Value	8,203	9,015
Level 1
Assets:
Loans		0
Financial derivatives	154	47
Other Assets	0	0
Total Assets at fair value	1,544,301	1,289,893
Liabilities:
Financial derivatives	15	0
Total Liabilities at fair value	15	0
Level 1 | Investment securities
Assets:
Fair  Value	1,544,147	1,289,846
Level 1 | Auction-rate certificates backed by Government guaranteed student loans
Assets:
Fair  Value		0
Level 1 | Government/GSE guaranteed mortgage-backed securities
Assets:
Fair  Value	0	0
Level 1 | U.S. Treasuries
Assets:
Fair  Value	1,544,147	1,289,846
Level 1 | AgVantage
Assets:
Fair  Value	0	0
Level 1 | Interest-Only Farmer Mac Guaranteed Securities
Assets:
Fair  Value	0	0
Level 2
Assets:
Loans		6,160
Financial derivatives	44,721	27,742
Other Assets	0	0
Total Assets at fair value	5,341,739	4,677,594
Liabilities:
Financial derivatives	21,603	77,326
Total Liabilities at fair value	21,603	77,326
Level 2 | Investment securities
Assets:
Fair  Value	5,297,018	4,643,692
Level 2 | Auction-rate certificates backed by Government guaranteed student loans
Assets:
Fair  Value		0
Level 2 | Government/GSE guaranteed mortgage-backed securities
Assets:
Fair  Value	5,297,018	4,643,692
Level 2 | U.S. Treasuries
Assets:
Fair  Value	0	0
Level 2 | AgVantage
Assets:
Fair  Value	0	0
Level 2 | Interest-Only Farmer Mac Guaranteed Securities
Assets:
Fair  Value	0	0
Level 3
Assets:
Loans		0
Financial derivatives	0	0
Other Assets	4,897	5,382
Total Assets at fair value	6,744,017	5,539,404
Liabilities:
Financial derivatives	0	0
Total Liabilities at fair value	$ 0	$ 0
Percent of level three fair value assets and liabilities	19.00%	18.00%
Financial instruments level three percent	49.00%	48.00%
Level 3 | Investment securities
Assets:
Fair  Value	$ 6,739,120	$ 5,534,022
Level 3 | Auction-rate certificates backed by Government guaranteed student loans
Assets:
Fair  Value		19,476
Level 3 | Government/GSE guaranteed mortgage-backed securities
Assets:
Fair  Value	0	0
Level 3 | U.S. Treasuries
Assets:
Fair  Value	0	0
Level 3 | AgVantage
Assets:
Fair  Value	6,730,917	5,505,531
Level 3 | Interest-Only Farmer Mac Guaranteed Securities
Assets:
Fair  Value	$ 8,203	$ 9,015