Loans and Allowance for Loan Losses - Summary Pertaining to the Breakdown of the Company's Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	$ 42,275	$ 41,005
Commercial and industrial
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	12,266	11,714
Commercial real estate
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	1,016	915
Business banking
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	16,993	17,430
Residential real estate
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	8,127	6,815
Consumer home equity
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	3,524	3,602
Other consumer
Disclosure Detail Of Non Accrual Loans [Line Items]
Total non-accrual loans	$ 349	$ 529