Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Details) - Consumer - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 1,275,162	$ 1,274,203
Percentage of Total	100.00%	100.00%
Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 1,264,357	$ 1,263,335
Percentage of Total	99.20%	99.10%
Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 10,805	$ 10,868
Percentage of Total	0.80%	0.90%
Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 729,914	$ 726,679
Percentage of Total	100.00%	100.00%
Residential mortgage | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 723,284	$ 719,551
Percentage of Total	99.10%	99.00%
Residential mortgage | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 6,630	$ 7,128
Percentage of Total	0.90%	1.00%
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 463,566	$ 471,562
Percentage of Total	100.00%	100.00%
Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 459,420	$ 467,864
Percentage of Total	99.10%	99.20%
Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 4,146	$ 3,698
Percentage of Total	0.90%	0.80%
Installment and other consumer
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 70,960	$ 67,546
Percentage of Total	100.00%	100.00%
Installment and other consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 70,931	$ 67,504
Percentage of Total	100.00%	99.90%
Installment and other consumer | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 29	$ 42
Percentage of Total	0.00%	0.10%
Consumer construction
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 10,722	$ 8,416
Percentage of Total	100.00%	100.00%
Consumer construction | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 10,722	$ 8,416
Percentage of Total	100.00%	100.00%
Consumer construction | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 0	$ 0
Percentage of Total	0.00%	0.00%