LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Parenthetical) (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	$ 30,885,000	$ 10,199,000
Loans Past Due 90 days or more and Still Accruing	28,891,000	42,390,000
Nonaccrual	96,261,000	87,467,000
Loans held for investment	13,048,684,000	12,746,556,000
PCD Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	5,000,000.0	6,200,000
Florida region [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL		0
Nonaccrual	22,700,000	8,600,000
Loans held for investment	2,499,469,000	2,294,950,000
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	94,395,000	93,171,000
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,889,081,000	2,828,431,000
Residential Portfolio Segment [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,860,215,000	2,796,482,000
Residential Portfolio Segment [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	10,300,000	8,500,000
Loans held for investment	522,063,000	505,226,000
Residential Portfolio Segment [Member] \| Florida region [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	511,814,000	496,686,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	121,000	0
Loans Past Due 90 days or more and Still Accruing	6,096,000	7,404,000
Nonaccrual	28,866,000	31,949,000
Loans held for investment	2,800,832,000	2,736,179,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,771,966,000	2,704,230,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| PCD Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	4,100,000	5,300,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	520,969,000	504,098,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| Florida region [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	510,720,000	495,558,000
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	0
Residential Portfolio Segment [Member] \| Conventional Residential Mortgage Loans [Member] \| 30-59 Days Past Due [Member] \| Less Than Two Payments In Arrears [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	63,000,000.0	65,600,000
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	13,186,000	18,816,000
Nonaccrual	0	0
Loans held for investment	88,249,000	92,252,000
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	88,249,000	92,252,000
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,094,000	1,128,000
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member] \| Florida region [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,094,000	1,128,000
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	0
Residential Portfolio Segment [Member] \| FHA/VA Government-Guaranteed Loans [Member] \| 30-59 Days Past Due [Member] \| Less Than Two Payments In Arrears [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	8,600,000	8,800,000
Residential Portfolio Segment [Member] \| GNMA [Member] \| Repurchase Option Program [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	3,800,000	5,700,000
Residential Portfolio Segment [Member] \| Federal Housing Administration Loan [Member] \| Past Due, 15 Months Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	5,000,000.0	8,000,000.0
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	956,000	968,000
Loans Past Due 90 days or more and Still Accruing	0	0
Nonaccrual	5,591,000	1,365,000
Loans held for investment	259,863,000	228,396,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	24,550,000	43,969,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	0
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| 30-59 Days Past Due [Member] \| Less Than Two Payments In Arrears [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	100,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	15,513,000	1,189,000
Loans Past Due 90 days or more and Still Accruing	2,970,000	6,895,000
Nonaccrual	19,650,000	20,514,000
Loans held for investment	3,614,241,000	3,366,038,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	200,000
Loans held for investment	1,162,825,000	1,040,163,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	9,019,000	1,589,000
Commercial Portfolio Segment [Member] \| Commercial Mortgage Loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	13,288,000	6,732,000
Loans Past Due 90 days or more and Still Accruing	875,000	907,000
Nonaccrual	21,437,000	10,851,000
Loans held for investment	2,549,375,000	2,565,984,000
Commercial Portfolio Segment [Member] \| Commercial Mortgage Loans [Member] \| PCD Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	900,000	900,000
Commercial Portfolio Segment [Member] \| Commercial Mortgage Loans [Member] \| Florida region [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	12,200,000
Nonaccrual	12,200,000
Loans held for investment	784,194,000	698,090,000
Commercial Portfolio Segment [Member] \| Commercial Mortgage Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	0
Commercial Portfolio Segment [Member] \| Commercial Mortgage Loans [Member] \| 30-59 Days Past Due [Member] \| Less Than Two Payments In Arrears [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 1,900,000	$ 1,000,000.0

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