Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	$ 11,384	$ 6,142
Commercial real estate
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	269	398
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	9,890	2,695
Commercial construction
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	0	1,996
Residential mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	374	31
Home equity
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	847	987
Installment and other consumer
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	4	35
Performing TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans		16,786	14,901
Performing TDRs | Commercial real estate
Financing Receivable, Modifications [Line Items]
Restructured loans		2,054	2,579
Performing TDRs | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Restructured loans		7,026	3,946
Performing TDRs | Commercial construction
Financing Receivable, Modifications [Line Items]
Restructured loans		1,912	2,420
Performing TDRs | Residential mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans		2,214	2,039
Performing TDRs | Home equity
Financing Receivable, Modifications [Line Items]
Restructured loans		3,568	3,885
Performing TDRs | Installment and other consumer
Financing Receivable, Modifications [Line Items]
Restructured loans		12	32
Nonperforming TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans		11,088	11,150
Nonperforming TDRs | Commercial real estate
Financing Receivable, Modifications [Line Items]
Restructured loans		1,139	967
Nonperforming TDRs | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Restructured loans		6,646	3,197
Nonperforming TDRs | Commercial construction
Financing Receivable, Modifications [Line Items]
Restructured loans		406	2,413
Nonperforming TDRs | Residential mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans		1,543	3,585
Nonperforming TDRs | Home equity
Financing Receivable, Modifications [Line Items]
Restructured loans		1,349	979
Nonperforming TDRs | Installment and other consumer
Financing Receivable, Modifications [Line Items]
Restructured loans		5	9
Total TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans		27,874	26,051
Total TDRs | Commercial real estate
Financing Receivable, Modifications [Line Items]
Restructured loans		3,193	3,546
Total TDRs | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Restructured loans		13,672	7,143
Total TDRs | Commercial construction
Financing Receivable, Modifications [Line Items]
Restructured loans		2,318	4,833
Total TDRs | Residential mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans		3,757	5,624
Total TDRs | Home equity
Financing Receivable, Modifications [Line Items]
Restructured loans		4,917	4,864
Total TDRs | Installment and other consumer
Financing Receivable, Modifications [Line Items]
Restructured loans		$ 17	$ 41

[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