CREDIT QUALITY ASSESSMENT - Non-accrual Loans (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	$ 88,219	$ 72,562
Contractual interest income due on non- accrual loans during the period	4,516	18,301
Commercial real estate: | Commercial investor real estate
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	36,365	26,849
Contractual interest income due on non- accrual loans during the period	1,825	6,547
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	9,479	6,605
Contractual interest income due on non- accrual loans during the period	645	2,741
Commercial real estate: | Commercial AD&C
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	11,383	4,267
Contractual interest income due on non- accrual loans during the period	565	4,505
Commercial Business
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	13,742	16,532
Contractual interest income due on non- accrual loans during the period	847	2,858
Residential real estate: | Residential mortgage
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	9,689	11,634
Contractual interest income due on non- accrual loans during the period	312	918
Residential real estate: | Residential construction
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	31	0
Contractual interest income due on non- accrual loans during the period	2	0
Consumer
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	7,530	6,675
Contractual interest income due on non- accrual loans during the period	$ 320	$ 732