Loan Portfolio and Credit Quality Nonaccrual Loans by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	$ 17,565	$ 14,057
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	800	2,554
Commercial tax-exempt
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	0	0
Total commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	800	2,554
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	0	546
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	14,219	7,914
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	2,545	3,031
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Nonaccrual loan receivable	$ 1	$ 12