LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 11,206,874	$ 11,060,658
Loans Past Due 90 days or more and Still Accruing	94,361	114,679
Nonaccrual	99,110	110,717
Nonaccrual Loans with No ACL	26,502	27,733
Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	10,921,180	10,744,930
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	47,964	44,202
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	44,259	46,130
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,851,685	2,978,895
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,730,525	2,853,503
Loans Past Due 90 days or more and Still Accruing	21,614	28,433
Nonaccrual	44,588	55,127
Nonaccrual Loans with No ACL	3,351	3,689
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,633,359	2,738,111
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] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	30,964	31,832
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	121,160	125,392
Loans Past Due 90 days or more and Still Accruing	55,752	65,515
Nonaccrual	0	0
Nonaccrual Loans with No ACL	0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	63,062	57,522
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] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,346	2,355
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,862,917	2,887,251
Loans Past Due 90 days or more and Still Accruing	11,972	7,827
Nonaccrual	17,079	17,135
Nonaccrual Loans with No ACL	11,619	11,393
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,828,679	2,858,397
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	4,990	2,047
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	197	1,845
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,270,113	2,167,469
Loans Past Due 90 days or more and Still Accruing	1,613	9,919
Nonaccrual	24,753	25,337
Nonaccrual Loans with No ACL	7,736	8,289
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,243,330	2,129,375
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	2,402
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	417	436
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	115,310	138,999
Loans Past Due 90 days or more and Still Accruing	3	0
Nonaccrual	2,375	2,664
Nonaccrual Loans with No ACL	982	1,000
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	112,932	136,317
Commercial Portfolio Segment [Member] | Construction Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	0	18
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
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,106,849	2,888,044
Consumer Portfolio Segment [Member] | Auto loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,710,229	1,571,540
Loans Past Due 90 days or more and Still Accruing	0	0
Nonaccrual	6,916	6,684
Nonaccrual Loans with No ACL	2,535	3,146
Consumer Portfolio Segment [Member] | Auto loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,668,658	1,533,445
Consumer Portfolio Segment [Member] | Auto loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	29,884	26,462
Consumer Portfolio Segment [Member] | Auto loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	4,771	4,949
Consumer Portfolio Segment [Member] | Finance Leases [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	633,781	575,005
Loans Past Due 90 days or more and Still Accruing	0	0
Nonaccrual	1,047	866
Nonaccrual Loans with No ACL	266	196
Consumer Portfolio Segment [Member] | Finance Leases [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	626,352	568,606
Consumer Portfolio Segment [Member] | Finance Leases [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	5,234	4,820
Consumer Portfolio Segment [Member] | Finance Leases [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,148	713
Consumer Portfolio Segment [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	327,146	316,182
Loans Past Due 90 days or more and Still Accruing	0	0
Nonaccrual	893	1,208
Nonaccrual Loans with No ACL	0	0
Consumer Portfolio Segment [Member] | Personal Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	321,892	310,390
Consumer Portfolio Segment [Member] | Personal Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,903	3,299
Consumer Portfolio Segment [Member] | Personal Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,458	1,285
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	297,289	290,226
Loans Past Due 90 days or more and Still Accruing	3,407	2,985
Nonaccrual	0	0
Nonaccrual Loans with No ACL	0	0
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	288,774	282,179
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,096	3,158
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,012	1,904
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	138,404	135,091
Loans Past Due 90 days or more and Still Accruing	0	0
Nonaccrual	1,459	1,696
Nonaccrual Loans with No ACL	13	20
Consumer Portfolio Segment [Member] | Other Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	134,142	130,588
Consumer Portfolio Segment [Member] | Other Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,857	1,996
Consumer Portfolio Segment [Member] | Other Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 946	$ 811