Allowance For Loan Losses - Adversely Classified Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	$ 2,687,228	$ 2,568,562
Adversely classified loans to total loans	1.21%	1.45%
Commercial real estate
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	$ 1,442,150	$ 1,394,179
Commercial and industrial
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	537,790	501,227
Commercial construction
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	345,683	317,477
Residential mortgages
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	254,188	247,373
Home equity
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	97,223	98,252
Consumer
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	10,194	10,054
Substandard
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	30,061	34,749
Substandard | Commercial real estate
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	13,273	16,664
Substandard | Commercial and industrial
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	8,550	10,900
Substandard | Commercial construction
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	5,809	4,836
Substandard | Residential mortgages
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	1,799	1,825
Substandard | Home equity
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	565	455
Substandard | Consumer
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	65	69
Doubtful
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	2,353	2,373
Doubtful | Commercial real estate
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Doubtful | Commercial and industrial
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	2,352	2,370
Doubtful | Commercial construction
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Doubtful | Residential mortgages
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Doubtful | Home equity
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Doubtful | Consumer
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	1	3
Loss
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Commercial real estate
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Commercial and industrial
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Commercial construction
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Residential mortgages
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Home equity
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Loss | Consumer
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	0	0
Not Adversely Classified
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	2,654,814	2,531,440
Not Adversely Classified | Commercial real estate
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	1,428,877	1,377,515
Not Adversely Classified | Commercial and industrial
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	526,888	487,957
Not Adversely Classified | Commercial construction
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	339,874	312,641
Not Adversely Classified | Residential mortgages
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	252,389	245,548
Not Adversely Classified | Home equity
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	96,658	97,797
Not Adversely Classified | Consumer
Financing Receivable, Credit Quality Indicators [Line Items]
Gross loans	$ 10,128	$ 9,982