Allowance for Credit Losses and Credit Quality - Summary of TDR Modifications (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]
Pre-modification Investment	$ 42,991	$ 2,839	$ 58,466	$ 39,130
Post-modification Investment	42,957	2,838	58,194	39,111
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	35,113	0	43,009	31,518
Post-modification Investment	35,079	0	42,886	31,518
Commercial | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	5,378	0	10,742	0
Post-modification Investment	5,344	0	10,709	0
Commercial | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	29,735	0	32,267	31,518
Post-modification Investment	29,735	0	32,177	31,518
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	7,878	2,839	15,457	7,612
Post-modification Investment	7,878	2,838	15,308	7,593
Consumer | Residential mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	4,994	1,724	10,423	4,023
Post-modification Investment	4,994	1,723	10,423	4,016
Consumer | Consumer installment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	88	0	481	0
Post-modification Investment	88	0	391	0
Consumer | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Pre-modification Investment	2,796	1,115	4,553	3,589
Post-modification Investment	$ 2,796	$ 1,115	$ 4,494	$ 3,577