CREDIT QUALITY ASSESSMENT - Collateral dependent loans individually evaluated for credit loss (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	$ 10,592	$ 20,717
Allowance related to loans evaluated individually	7,537	11,405
Loans individually evaluated for credit loss without an allowance	27,831	77,001
Total individually evaluated collateral dependent loans	38,423	97,718
Total unpaid contractual principal balance	53,015	115,816
Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	8,590	17,419
Loans individually evaluated for credit loss without an allowance	10,449	71,764
Total individually evaluated collateral dependent loans	19,039	89,183
Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,473	2,709
Loans individually evaluated for credit loss without an allowance	15,712	3,509
Total individually evaluated collateral dependent loans	17,185	6,218
Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	529	589
Loans individually evaluated for credit loss without an allowance	1,670	1,728
Total individually evaluated collateral dependent loans	2,199	2,317
Commercial real estate: | Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,144	5,612
Allowance related to loans evaluated individually	203	1,273
Loans individually evaluated for credit loss without an allowance	14,242	39,615
Total individually evaluated collateral dependent loans	15,386	45,227
Total unpaid contractual principal balance	24,990	49,920
Commercial real estate: | Commercial investor real estate | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	808	4,913
Loans individually evaluated for credit loss without an allowance	4,731	39,615
Total individually evaluated collateral dependent loans	5,539	44,528
Commercial real estate: | Commercial investor real estate | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	336	699
Loans individually evaluated for credit loss without an allowance	9,511	0
Total individually evaluated collateral dependent loans	9,847	699
Commercial real estate: | Commercial investor real estate | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Allowance related to loans evaluated individually	0	0
Loans individually evaluated for credit loss without an allowance	9,854	11,561
Total individually evaluated collateral dependent loans	9,854	11,561
Total unpaid contractual principal balance	11,867	15,309
Commercial real estate: | Commercial owner-occupied real estate | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	5,318	9,315
Total individually evaluated collateral dependent loans	5,318	9,315
Commercial real estate: | Commercial owner-occupied real estate | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	4,536	2,246
Total individually evaluated collateral dependent loans	4,536	2,246
Commercial real estate: | Commercial owner-occupied real estate | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,022	1,328
Allowance related to loans evaluated individually	509	603
Loans individually evaluated for credit loss without an allowance	0	13,716
Total individually evaluated collateral dependent loans	1,022	15,044
Total unpaid contractual principal balance	1,090	16,040
Commercial real estate: | Commercial AD&C | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,022	1,328
Loans individually evaluated for credit loss without an allowance	0	13,716
Total individually evaluated collateral dependent loans	1,022	15,044
Commercial real estate: | Commercial AD&C | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Commercial real estate: | Commercial AD&C | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Commercial Business
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	8,426	13,777
Allowance related to loans evaluated individually	6,825	9,529
Loans individually evaluated for credit loss without an allowance	1,662	9,871
Total individually evaluated collateral dependent loans	10,088	23,648
Total unpaid contractual principal balance	11,912	30,958
Commercial Business | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	6,760	11,178
Loans individually evaluated for credit loss without an allowance	400	9,118
Total individually evaluated collateral dependent loans	7,160	20,296
Commercial Business | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,137	2,010
Loans individually evaluated for credit loss without an allowance	1,157	627
Total individually evaluated collateral dependent loans	2,294	2,637
Commercial Business | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	529	589
Loans individually evaluated for credit loss without an allowance	105	126
Total individually evaluated collateral dependent loans	634	715
Residential real estate: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Allowance related to loans evaluated individually	0	0
Loans individually evaluated for credit loss without an allowance	1,716	1,874
Total individually evaluated collateral dependent loans	1,716	1,874
Total unpaid contractual principal balance	2,792	3,225
Residential real estate: | Residential mortgage | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Residential real estate: | Residential mortgage | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	151	272
Total individually evaluated collateral dependent loans	151	272
Residential real estate: | Residential mortgage | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	1,565	1,602
Total individually evaluated collateral dependent loans	1,565	1,602
Residential real estate: | Residential construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Allowance related to loans evaluated individually	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Total unpaid contractual principal balance	0	0
Residential real estate: | Residential construction | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Residential real estate: | Residential construction | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Residential real estate: | Residential construction | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Allowance related to loans evaluated individually	0	0
Loans individually evaluated for credit loss without an allowance	357	364
Total individually evaluated collateral dependent loans	357	364
Total unpaid contractual principal balance	364	364
Consumer | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	0	0
Consumer | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	357	364
Total individually evaluated collateral dependent loans	357	364
Consumer | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0	0
Loans individually evaluated for credit loss without an allowance	0	0
Total individually evaluated collateral dependent loans	$ 0	$ 0