FAIR VALUE DISCLOSURES - Schedule of Fair Value, by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Financial Assets:
Financial derivatives	$ 42,411	$ 44,875
Guarantee and commitment fees receivable	58,476	57,214
Financial liabilities:
Financial derivatives	69,282	21,618
Guarantee and commitment obligation	55,555	54,770
Level 1
Financial Assets:
Financial derivatives	43	154
Financial liabilities:
Financial derivatives	22	15
Level 2
Financial Assets:
Financial derivatives	42,368	44,721
Financial liabilities:
Financial derivatives	69,260	21,603
Level 3
Financial Assets:
Financial derivatives	0	0
Financial liabilities:
Financial derivatives	0	0
Carrying Value
Financial Assets:
Cash and cash equivalents	1,038,091	931,067
Investment securities	19,425,162	17,550,379
Loans	18,180,844	16,321,276
Financial derivatives	42,411	44,875
Guarantee and commitment fees receivable	58,476	57,214
Financial liabilities:
Notes payable	34,693,922	30,822,570
Debt securities of consolidated trusts held by third parties	2,217,532	2,365,435
Financial derivatives	69,282	21,618
Guarantee and commitment obligation	55,555	54,770
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	1,038,091	931,067
Investment securities	19,238,583	17,390,108
Loans	18,226,446	16,342,149
Financial derivatives	42,411	44,875
Guarantee and commitment fees receivable	62,164	63,677
Financial liabilities:
Notes payable	34,237,982	30,489,417
Debt securities of consolidated trusts held by third parties	2,251,451	2,420,149
Financial derivatives	69,282	21,618
Guarantee and commitment obligation	59,245	61,234
Estimated Fair Value | Level 1
Financial Assets:
Cash and cash equivalents	1,038,091	931,067
Investment securities	1,498,059	1,544,147
Loans	0	0
Financial derivatives	43	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	22	15
Guarantee and commitment obligation	0	0
Estimated Fair Value | Level 2
Financial Assets:
Cash and cash equivalents	0	0
Investment securities	5,616,878	5,297,018
Loans	0	0
Financial derivatives	42,368	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	69,260	21,603
Guarantee and commitment obligation	0	0
Estimated Fair Value | Level 3
Financial Assets:
Cash and cash equivalents	0	0
Investment securities	12,123,646	10,548,943
Loans	18,226,446	16,342,149
Financial derivatives	0	0
Guarantee and commitment fees receivable	62,164	63,677
Financial liabilities:
Notes payable	34,237,982	30,489,417
Debt securities of consolidated trusts held by third parties	2,251,451	2,420,149
Financial derivatives	0	0
Guarantee and commitment obligation	$ 59,245	$ 61,234