LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 11,206,874	$ 11,060,658
Nonaccrual Loans with No ACL	26,502	27,733
Loans Past Due 90 days or more and Still Accruing	94,361	114,679
Nonaccrual	99,110	110,717
Total TDR loans	394,500
Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Total TDR loans	345,400	363,400
PCD loans [Member]
Financing Receivable, Past Due [Line Items]
Loans Past Due 90 days or more and Still Accruing	15,300	20,600
Florida region [Member}
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,989,147	1,946,740
Nonaccrual	7,100	8,200
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	47,964	44,202
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,851,685	2,978,895
Residential Portfolio Segment [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,807,097	2,923,768
Residential Portfolio Segment [Member] \| Florida region [Member}
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	407,153	429,322
Residential Portfolio Segment [Member] \| Florida region [Member} \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	401,181	422,170
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,730,525	2,853,503
Nonaccrual Loans with No ACL	3,351	3,689
Loans Past Due 90 days or more and Still Accruing	21,614	28,433
Nonaccrual	44,588	55,127
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,685,937	2,798,376
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	14,300	19,100
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Florida region [Member}
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	406,421	428,582
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Florida region [Member} \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	400,449	421,430
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Less Than Two Payments In Arrears [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	61,600	66,000
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	121,160	125,392
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	55,752	65,515
Nonaccrual	0	0
Total TDR loans	55,100	57,600
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	121,160	125,392
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Florida region [Member}
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	732	740
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Florida region [Member} \| Performing Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	732	740
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
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	35,600	46,600
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Less Than Two Payments In Arrears [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,700	6,100
Residential Portfolio Segment [Member] \| GNMA [Member] \| Repurchase Option Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	10,800	7,200
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,862,917	2,887,251
Nonaccrual Loans with No ACL	11,619	11,393
Loans Past Due 90 days or more and Still Accruing	11,972	7,827
Nonaccrual	17,079	17,135
Commercial Portfolio Segment [Member] \| Florida region [Member} \| Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	993,707	940,654
Nonaccrual Loans with No ACL	400	500
Commercial Portfolio Segment [Member] \| 30-59 Days Past Due [Member] \| Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,990	2,047
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,270,113	2,167,469
Nonaccrual Loans with No ACL	7,736	8,289
Loans Past Due 90 days or more and Still Accruing	1,613	9,919
Nonaccrual	24,753	25,337
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	1,500
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member] \| Florida region [Member}
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	485,234	465,238
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	2,402
Commercial Portfolio Segment [Member] \| Less Than Two Payments In Arrears [Member] \| Mortgage Receivable [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 700	$ 700

Amount of financing receivable modified as troubled debt restructuring.

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