Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Details) - Consumer - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 1,624,356	$ 1,274,203
% of Total	100.00%	100.00%
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 1,614,158	$ 1,263,335
% of Total	99.40%	99.10%
Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 10,198	$ 10,868
% of Total	0.60%	0.90%
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 998,585	$ 726,679
% of Total	100.00%	100.00%
Residential mortgage | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 991,066	$ 719,551
% of Total	99.20%	99.00%
Residential mortgage | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 7,519	$ 7,128
% of Total	0.80%	1.00%
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 538,348	$ 471,562
% of Total	100.00%	100.00%
Home equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 535,709	$ 467,864
% of Total	99.50%	99.20%
Home equity | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 2,639	$ 3,698
% of Total	0.50%	0.80%
Installment and other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 79,033	$ 67,546
% of Total	100.00%	100.00%
Installment and other consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 78,993	$ 67,504
% of Total	99.90%	99.90%
Installment and other consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 40	$ 42
% of Total	0.10%	0.10%
Consumer construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 8,390	$ 8,416
% of Total	100.00%	100.00%
Consumer construction | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 8,390	$ 8,416
% of Total	100.00%	100.00%
Consumer construction | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans recorded investment	$ 0	$ 0
% of Total	0.00%	0.00%