FAIR VALUE DISCLOSURES - Schedule of Fair Value, by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Financial Assets:
Financial derivatives	$ 19,912	$ 44,875
Guarantee and commitment fees receivable	56,272	57,214
Financial liabilities:
Financial derivatives	219,897	21,618
Guarantee and commitment obligation	54,439	54,770
Level 1
Financial Assets:
Financial derivatives	0	154
Financial liabilities:
Financial derivatives	44	15
Level 2
Financial Assets:
Financial derivatives	19,912	44,721
Financial liabilities:
Financial derivatives	219,853	21,603
Level 3
Financial Assets:
Financial derivatives	0	0
Financial liabilities:
Financial derivatives	0	0
Carrying Value
Financial Assets:
Cash and cash equivalents	991,445	931,067
Investment securities	19,380,891	17,550,379
Loans	18,867,511	16,321,276
Financial derivatives	19,912	44,875
Guarantee and commitment fees receivable	56,272	57,214
Financial liabilities:
Notes payable	35,416,101	30,822,570
Debt securities of consolidated trusts held by third parties	2,115,699	2,365,435
Financial derivatives	219,897	21,618
Guarantee and commitment obligation	54,439	54,770
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	991,445	931,067
Investment securities	19,076,622	17,390,108
Loans	18,473,346	16,342,149
Financial derivatives	19,912	44,875
Guarantee and commitment fees receivable	59,431	63,677
Financial liabilities:
Notes payable	34,728,336	30,489,417
Debt securities of consolidated trusts held by third parties	2,053,297	2,420,149
Financial derivatives	219,897	21,618
Guarantee and commitment obligation	57,598	61,234
Estimated Fair Value | Level 1
Financial Assets:
Cash and cash equivalents	991,445	931,067
Investment securities	1,561,091	1,544,147
Loans	0	0
Financial derivatives	0	154
Guarantee and commitment fees receivable	0	0
Financial liabilities:
Notes payable	0	0
Debt securities of consolidated trusts held by third parties	0	0
Financial derivatives	44	15
Guarantee and commitment obligation	0	0
Estimated Fair Value | Level 2
Financial Assets:
Cash and cash equivalents	0	0
Investment securities	5,762,016	5,297,018
Loans	0	0
Financial derivatives	19,912	44,721
Guarantee and commitment fees receivable	0	0
Financial liabilities:
Notes payable	0	0
Debt securities of consolidated trusts held by third parties	0	0
Financial derivatives	219,853	21,603
Guarantee and commitment obligation	0	0
Estimated Fair Value | Level 3
Financial Assets:
Cash and cash equivalents	0	0
Investment securities	11,753,515	10,548,943
Loans	18,473,346	16,342,149
Financial derivatives	0	0
Guarantee and commitment fees receivable	59,431	63,677
Financial liabilities:
Notes payable	34,728,336	30,489,417
Debt securities of consolidated trusts held by third parties	2,053,297	2,420,149
Financial derivatives	0	0
Guarantee and commitment obligation	$ 57,598	$ 61,234