Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	$ 22,650	$ 32,206
Commercial real estate | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	4,791	25,159
Commercial and industrial | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	13,716	5,661
Commercial construction | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	2,329
Business banking | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	165
Consumer real estate | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	1,645
Residential mortgage | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		340
Home equity | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		1,037
Other consumer | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	4
Performing TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	17,460	36,960
Performing TDRs | Commercial real estate | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	14	22,233
Performing TDRs | Commercial and industrial | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	7,090	6,909
Performing TDRs | Commercial construction | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	3,267	1,425
Performing TDRs | Business banking | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	1,503
Performing TDRs | Consumer real estate | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	5,581
Performing TDRs | Residential mortgage | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		2,013
Performing TDRs | Home equity | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		4,371
Performing TDRs | Other consumer | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	5	9
Nonperforming TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	29,289	8,912
Nonperforming TDRs | Commercial real estate | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	16,654	6,713
Nonperforming TDRs | Commercial and industrial | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	9,885	695
Nonperforming TDRs | Commercial construction | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	0	0
Nonperforming TDRs | Business banking | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	430
Nonperforming TDRs | Consumer real estate | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	2,319
Nonperforming TDRs | Residential mortgage | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		822
Nonperforming TDRs | Home equity | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		678
Nonperforming TDRs | Other consumer | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	0	4
Total TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	46,748	45,872
Total TDRs | Commercial real estate | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	16,668	28,946
Total TDRs | Commercial and industrial | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	16,975	7,604
Total TDRs | Commercial construction | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	3,267	1,425
Total TDRs | Business banking | Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	1,933
Total TDRs | Consumer real estate | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	7,900
Total TDRs | Residential mortgage | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		2,835
Total TDRs | Home equity | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans		5,049
Total TDRs | Other consumer | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	$ 5	$ 13