LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	$ 20,479	$ 25,026
Loans Past Due 90 days or more and Still Accruing	63,211	80,283
Nonaccrual	82,021	89,935
Loans held for investment	11,719,315	11,552,825
PCD loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	9,500	12,000
Florida region [Member}
Financing Receivable, Past Due [Line Items]
Nonaccrual	9,800	8,300
Loans held for investment	1,998,269	2,088,351
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	70,168	58,718
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,793,790	2,847,290
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,760,538	2,804,518
Residential Portfolio Segment [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	441,480	429,390
Residential Portfolio Segment [Member] | Florida region [Member} | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	434,042	422,089
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	1,861	2,292
Loans Past Due 90 days or more and Still Accruing	12,915	16,821
Nonaccrual	33,252	42,772
Loans held for investment	2,688,905	2,729,132
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,655,653	2,686,360
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	8,500	11,000
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	440,752	428,648
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	433,314	421,347
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	62,900	65,200
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	34,038	48,456
Nonaccrual	0	0
Loans held for investment	104,885	118,158
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	104,885	118,158
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	728	742
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	728	742
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	6,600	6,100
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Past Due, 15 Months Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	19,900	28,200
Residential Portfolio Segment [Member] | GNMA [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	6,500	10,400
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	6,500	10,300
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	1,816	3,300
Loans Past Due 90 days or more and Still Accruing	5,037	6,332
Nonaccrual	9,194	7,830
Loans held for investment	2,946,201	2,886,263
Commercial Portfolio Segment [Member] | Florida region [Member} | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	300	300
Loans held for investment	934,427	1,026,154
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	1,827	1,984
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	11,834	15,991
Loans Past Due 90 days or more and Still Accruing	5,553	3,771
Nonaccrual	21,536	22,319
Loans held for investment	2,320,069	2,358,851
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	1,000	1,000
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	519,780	524,647
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	4,551	300
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	1,900	1,600
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual Loans with No ACL	973	977
Loans Past Due 90 days or more and Still Accruing	0	128
Nonaccrual	1,677	2,208
Loans held for investment	163,998	132,953
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Florida region [Member}
Financing Receivable, Past Due [Line Items]
Loans held for investment	94,779	98,181
Commercial Portfolio Segment [Member] | Construction Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,062	$ 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	$ 200