Allowance for Loan and Lease Losses and Credit Quality Information - Schedule of Loans Identified as Troubled Debt Restructurings During Periods Indicated (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	$ 6,914	$ 10,250
Owner-occupied commercial
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	1,367	0
Commercial
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	1,134	5,102
Commercial mortgages
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	1,136	2,190
Construction
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	0	920
Residential
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	1,231	557
Consumer loan commitments
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring Identified During Period	$ 2,046	$ 1,481