Allowance for Credit Losses and Credit Quality - Summary of Defaulted TDR Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	$ 530	$ 746	$ 2,163	$ 3,144
Commercial | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	60	0	283	297
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	470	746	1,880	2,847
Consumer | Residential mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	265	212	1,404	964
Consumer | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	170	82	426	328
Consumer | Consumer installment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Defaulted TDR loan balance modified during the period	$ 35	$ 452	$ 50	$ 1,555