LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Parenthetical) (Detail) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 12,185,483,000	$ 11,552,825,000
Nonaccrual Loans with No ACL	6,953,000	25,026,000
Loans Past Due 90 days or more and Still Accruing	59,452,000	80,283,000
Nonaccrual	83,707,000	89,935,000
PCD loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	8,300,000	12,000,000.0
Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,022,261,000	2,088,351,000	$ 1,948,716,000
Nonaccrual Loans with No ACL	0
Nonaccrual	8,000,000	8,300,000
Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	11,891,511,000	11,277,708,000
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	89,185,000	58,718,000
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	61,628,000	46,181,000
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,821,726,000	2,847,290,000
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,789,487,000	2,804,518,000
Residential Portfolio Segment [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	465,720,000	429,390,000
Residential Portfolio Segment [Member] | Florida region [Member} | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	458,493,000	422,089,000
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,721,490,000	2,729,132,000
Nonaccrual Loans with No ACL	1,742,000	2,292,000
Loans Past Due 90 days or more and Still Accruing	11,029,000	16,821,000
Nonaccrual	32,239,000	42,772,000
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,689,251,000	2,686,360,000
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	7,400,000	11,000,000.0
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	464,777,000	428,648,000
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	457,550,000	421,347,000
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,644,344,000	2,643,909,000
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	69,900,000	65,200,000
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	33,878,000	25,630,000
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	100,236,000	118,158,000
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	29,312,000	48,456,000
Nonaccrual	0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	100,236,000	118,158,000
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	943,000	742,000
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	943,000	742,000
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	68,332,000	67,116,000
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	8,200,000	6,100,000
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,592,000	2,586,000
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	7,900,000	10,300,000
Residential Portfolio Segment [Member] | GNMA [Member] | Past Due [Member] | Repurchase Option Program [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	7,900,000	10,400,000
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	15,400,000	28,200,000
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,174,232,000	2,886,263,000
Nonaccrual Loans with No ACL	1,687,000	3,300,000
Loans Past Due 90 days or more and Still Accruing	8,455,000	6,332,000
Nonaccrual	15,250,000	7,830,000
Commercial Portfolio Segment [Member] | Florida region [Member} | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	924,824,000	1,026,154,000
Nonaccrual Loans with No ACL		300,000
Commercial Portfolio Segment [Member] | Current [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,148,254,000	2,868,989,000
Commercial Portfolio Segment [Member] | 30-59 Days Past Due [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,130,000	1,984,000
Commercial Portfolio Segment [Member] | 60-89 Days Past Due [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,143,000	1,128,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,317,083,000	2,358,851,000
Nonaccrual Loans with No ACL	2,536,000	15,991,000
Loans Past Due 90 days or more and Still Accruing	1,108,000	3,771,000
Nonaccrual	12,205,000	22,319,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | PCD loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	900,000	1,000,000.0
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	526,446,000	524,647,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,303,753,000	2,330,094,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	17,000	300,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 30-59 Days Past Due [Member] | Less Than Two Payments In Arrears [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,100,000	1,600,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	2,367,000
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	214,777,000	132,953,000
Nonaccrual Loans with No ACL	972,000	977,000
Loans Past Due 90 days or more and Still Accruing	2,297,000	128,000
Nonaccrual	1,569,000	2,208,000
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	99,376,000	98,181,000
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	210,911,000	130,617,000
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] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 0	$ 0