LOANS HELD FOR INVESTMENT - Breakdown Between Accrual and Nonaccrual Status of TDRs (Detail) - TDR - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	$ 393,327	$ 398,257
Financing Receivable Modifications Recorded Investment Nonaccrual Status	85,869	89,740
Financing Receivable, Modifications, Recorded Investment	479,196	487,997	$ 582,647	$ 587,219
Residential Portfolio Segment [Member] | Conventional Loan [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	256,779	265,746
Financing Receivable Modifications Recorded Investment Nonaccrual Status	53,827	50,903
Financing Receivable, Modifications, Recorded Investment	310,606	316,649
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	73,649	59,689
Financing Receivable Modifications Recorded Investment Nonaccrual Status	6,833	7,160
Financing Receivable, Modifications, Recorded Investment	80,482	66,849
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	45,627	51,062
Financing Receivable Modifications Recorded Investment Nonaccrual Status	18,811	23,917
Financing Receivable, Modifications, Recorded Investment	64,438	74,979
Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	20,200
Construction loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	2,480	3,238
Financing Receivable Modifications Recorded Investment Nonaccrual Status	943	1,083
Financing Receivable, Modifications, Recorded Investment	3,423	4,321
Auto loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	6,551	8,556
Financing Receivable Modifications Recorded Investment Nonaccrual Status	4,968	5,984
Financing Receivable, Modifications, Recorded Investment	11,519	14,540
Finance Leases [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	1,125	1,502
Financing Receivable Modifications Recorded Investment Nonaccrual Status	19	30
Financing Receivable, Modifications, Recorded Investment	1,144	1,532
Personal Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	920	1,052
Financing Receivable Modifications Recorded Investment Nonaccrual Status	4	21
Financing Receivable, Modifications, Recorded Investment	924	1,073
Credit Cards | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	2,358	2,791
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	2,358	2,791
Other Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	3,838	4,621
Financing Receivable Modifications Recorded Investment Nonaccrual Status	464	642
Financing Receivable, Modifications, Recorded Investment	4,302	5,263
PR And VI [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	386,720	388,388
Financing Receivable Modifications Recorded Investment Nonaccrual Status	85,297	89,388
Financing Receivable, Modifications, Recorded Investment	472,017	477,776
PR And VI [Member] | Residential Portfolio Segment [Member] | Conventional Loan [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	253,421	262,244
Financing Receivable Modifications Recorded Investment Nonaccrual Status	53,516	50,903
Financing Receivable, Modifications, Recorded Investment	306,937	313,147
PR And VI [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	73,649	59,689
Financing Receivable Modifications Recorded Investment Nonaccrual Status	6,609	6,845
Financing Receivable, Modifications, Recorded Investment	80,258	66,534
PR And VI [Member] | Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	43,012	45,534
Financing Receivable Modifications Recorded Investment Nonaccrual Status	18,811	23,917
Financing Receivable, Modifications, Recorded Investment	61,823	69,451
PR And VI [Member] | Construction loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	2,480	3,238
Financing Receivable Modifications Recorded Investment Nonaccrual Status	943	1,083
Financing Receivable, Modifications, Recorded Investment	3,423	4,321
PR And VI [Member] | Auto loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	6,481	8,440
Financing Receivable Modifications Recorded Investment Nonaccrual Status	4,968	5,984
Financing Receivable, Modifications, Recorded Investment	11,449	14,424
PR And VI [Member] | Finance Leases [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	1,125	1,502
Financing Receivable Modifications Recorded Investment Nonaccrual Status	19	30
Financing Receivable, Modifications, Recorded Investment	1,144	1,532
PR And VI [Member] | Personal Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	920	1,052
Financing Receivable Modifications Recorded Investment Nonaccrual Status	4	21
Financing Receivable, Modifications, Recorded Investment	924	1,073
PR And VI [Member] | Credit Cards | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	2,358	2,791
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	2,358	2,791
PR And VI [Member] | Other Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	3,274	3,898
Financing Receivable Modifications Recorded Investment Nonaccrual Status	427	605
Financing Receivable, Modifications, Recorded Investment	3,701	4,503
FL
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	6,607	9,869
Financing Receivable Modifications Recorded Investment Nonaccrual Status	572	352
Financing Receivable, Modifications, Recorded Investment	7,179	10,221
FL | Residential Portfolio Segment [Member] | Conventional Loan [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	3,358	3,502
Financing Receivable Modifications Recorded Investment Nonaccrual Status	311	0
Financing Receivable, Modifications, Recorded Investment	3,669	3,502
FL | Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	0	0
Financing Receivable Modifications Recorded Investment Nonaccrual Status	224	315
Financing Receivable, Modifications, Recorded Investment	224	315
FL | Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	2,615	5,528
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	2,615	5,528
FL | Construction loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	0	0
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	0	0
FL | Auto loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	70	116
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	70	116
FL | Finance Leases [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	0	0
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	0	0
FL | Personal Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	0	0
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	0	0
FL | Credit Cards | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	0	0
Financing Receivable Modifications Recorded Investment Nonaccrual Status	0	0
Financing Receivable, Modifications, Recorded Investment	0	0
FL | Other Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Financing Receivable Modifications Recorded Investment Accrual Status	564	723
Financing Receivable Modifications Recorded Investment Nonaccrual Status	37	37
Financing Receivable, Modifications, Recorded Investment	$ 601	$ 760