Loans and Allowance for Credit Losses - Summary of the Company's Loan participations (Detail) - Loan Participations and Assignments - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance (1)	$ 1,361,919	$ 1,132,502
Non-performing Loan Rate (%)	0.53%	0.88%
Gross Charge-offs	$ 3	$ 0
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance (1)	$ 878,861	$ 732,425
Non-performing Loan Rate (%)	0.82%	1.36%
Gross Charge-offs	$ 0	$ 0
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance (1)	$ 406,089	$ 362,898
Non-performing Loan Rate (%)	0.00%	0.00%
Gross Charge-offs	$ 0	$ 0
Commercial construction | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance (1)	$ 76,913	$ 37,081
Non-performing Loan Rate (%)	0.00%	0.00%
Gross Charge-offs	$ 0	$ 0
Business banking | Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance (1)	$ 56	$ 98
Non-performing Loan Rate (%)	0.00%	0.00%
Gross Charge-offs	$ 3	$ 0