Loan Portfolio and Credit Quality - Nonaccrual Loans by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	$ 25,764	$ 23,851
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	4,766	4,394
Commercial tax-exempt
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	0	0
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	5,859	5,261
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	14,475	13,780
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	651	415
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	$ 13	$ 1