Loans and Loans Held for Sale - Summary of Restructured Loans (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended			12 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019	Dec. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1],[2]	$ 1,304	$ 6,427	$ 7,853		$ 11,248
Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]	0	6,090	2,210		6,090
Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]	102	0	2,170		4,529
Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]	701	0	2,572		0
Residential Mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]	310	115	337		163
Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]	$ 191	213	564		457
Installment and other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans	[1]		$ 9			$ 9
Performing TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				15,536	[3]		$ 36,960
Performing TDRs | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				25			22,233
Performing TDRs | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				4,388			6,909
Performing TDRs | Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				3,997			1,425
Performing TDRs | Business banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				1,488
Performing TDRs | Consumer real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				5,635
Performing TDRs | Residential Mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							2,013
Performing TDRs | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							4,371
Performing TDRs | Other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				3
Performing TDRs | Installment and other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							9
Nonperforming TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				31,755	[3]		8,912
Nonperforming TDRs | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				27,100			6,713
Nonperforming TDRs | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				2,068			695
Nonperforming TDRs | Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				0			0
Nonperforming TDRs | Business banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				349
Nonperforming TDRs | Consumer real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				2,238
Nonperforming TDRs | Residential Mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							822
Nonperforming TDRs | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							678
Nonperforming TDRs | Other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				0
Nonperforming TDRs | Installment and other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							4
Total TDRs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				47,291	[3]		45,872
Total TDRs | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				27,125			28,946
Total TDRs | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				6,456			7,604
Total TDRs | Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				3,997			1,425
Total TDRs | Business banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				1,837
Total TDRs | Consumer real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				7,873
Total TDRs | Residential Mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							2,835
Total TDRs | Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							5,049
Total TDRs | Other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans				$ 3
Total TDRs | Installment and other consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loans							$ 13

[1] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

[2] Refer to Note 1, Basis of Presentation for details of reclassification of our portfolio segments related to the adoption of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instrument.

[3] Refer to Note 1, Basis of Presentation for details of reclassification of our portfolio segments related to the adoption of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.