LOANS HELD FOR INVESTMENT - Corporation's Aging of Loans Held for Investment Portfolio (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 11,950,932	$ 11,552,825
Nonaccrual Loans with No ACL	9,967	25,026
Loans Past Due 90 days or more and Still Accruing	62,892	80,283
Financing Receivable, Nonaccrual	93,164	89,935
Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	11,657,910	11,277,708
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	79,051	58,718
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	57,915	46,181
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,812,631	2,847,290
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,708,535	2,729,132
Nonaccrual Loans with No ACL	1,910	2,292
Loans Past Due 90 days or more and Still Accruing	11,958	16,821
Financing Receivable, Nonaccrual	31,946	42,772
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,633,303	2,643,909
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	31,328	25,630
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	104,096	118,158
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	32,167	48,456
Financing Receivable, Nonaccrual	0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	69,175	67,116
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	2,754	2,586
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,030,954	2,886,263
Nonaccrual Loans with No ACL	1,523	3,300
Loans Past Due 90 days or more and Still Accruing	10,749	6,332
Financing Receivable, Nonaccrual	18,809	7,830
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,998,999	2,868,989
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	441	1,984
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	1,956	1,128
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,316,113	2,358,851
Nonaccrual Loans with No ACL	5,458	15,991
Loans Past Due 90 days or more and Still Accruing	2,373	3,771
Financing Receivable, Nonaccrual	21,632	22,319
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,290,012	2,330,094
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	930	300
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,166	2,367
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	202,774	132,953
Nonaccrual Loans with No ACL	973	977
Loans Past Due 90 days or more and Still Accruing	7	128
Financing Receivable, Nonaccrual	1,640	2,208
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	199,293	130,617
Commercial Portfolio Segment [Member] | Construction Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,834	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
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,588,460	3,327,468
Consumer Portfolio Segment [Member] | Auto loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,903,185	1,798,071
Nonaccrual Loans with No ACL	102	2,136
Loans Past Due 90 days or more and Still Accruing	0	0
Financing Receivable, Nonaccrual	13,103	10,672
Consumer Portfolio Segment [Member] | Auto loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	1,826,679	1,740,271
Consumer Portfolio Segment [Member] | Auto loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	52,755	40,039
Consumer Portfolio Segment [Member] | Auto loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	10,648	7,089
Consumer Portfolio Segment [Member] | Finance Leases [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	831,540	718,230
Nonaccrual Loans with No ACL	0	330
Loans Past Due 90 days or more and Still Accruing	0	0
Financing Receivable, Nonaccrual	2,522	1,645
Consumer Portfolio Segment [Member] | Finance Leases [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	816,251	707,646
Consumer Portfolio Segment [Member] | Finance Leases [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	10,421	7,148
Consumer Portfolio Segment [Member] | Finance Leases [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,346	1,791
Consumer Portfolio Segment [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	377,850	353,246
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	0	0
Financing Receivable, Nonaccrual	1,874	1,248
Consumer Portfolio Segment [Member] | Personal Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	367,428	346,366
Consumer Portfolio Segment [Member] | Personal Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	5,708	3,738
Consumer Portfolio Segment [Member] | Personal Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,840	1,894
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	321,950	311,731
Nonaccrual Loans with No ACL	0	0
Loans Past Due 90 days or more and Still Accruing	5,638	4,775
Financing Receivable, Nonaccrual	0	0
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	308,519	301,013
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	4,563	3,705
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	3,230	2,238
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	153,935	146,190
Nonaccrual Loans with No ACL	1	0
Loans Past Due 90 days or more and Still Accruing	0	0
Financing Receivable, Nonaccrual	1,638	1,241
Consumer Portfolio Segment [Member] | Other Loans [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	148,251	141,687
Consumer Portfolio Segment [Member] | Other Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	2,399	1,804
Consumer Portfolio Segment [Member] | Other Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment	$ 1,647	$ 1,458