Allowance for Loan Losses - Past Due and Non-Accrual Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule of Aging of Financing Receivables [Line Items]
Number of days a loan must be paid current before accrual of interest is resumed	180 days
Total Past Due Loans	$ 29,488	$ 19,490
Current Loans	3,057,758	2,549,072
Gross Loans	3,087,246	2,568,562
Non-accrual Loans	$ 38,050	$ 14,771
The ratio of non-accrual loans to total loans	1.24%	0.58%
Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	$ 12,196	$ 9,541
Current Loans	1,466,039	1,384,638
Gross Loans	1,478,235	1,394,179
Non-accrual Loans	29,680	8,280
Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	1,037	1,875
Current Loans	434,623	499,352
Gross Loans	435,660	501,227
Non-accrual Loans	4,574	3,285
Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	14,817	5,636
Current Loans	358,492	311,841
Gross Loans	373,309	317,477
Non-accrual Loans	2,999	1,735
SBA paycheck protection program
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	0
Current Loans	453,084
Gross Loans	453,084	0
Non-accrual Loans	0
Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	1,180	1,606
Current Loans	251,791	245,767
Gross Loans	252,971	247,373
Non-accrual Loans	414	411
Home equity
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	255	814
Current Loans	84,751	97,438
Gross Loans	85,006	98,252
Non-accrual Loans	381	1,040
Consumer
Schedule of Aging of Financing Receivables [Line Items]
Total Past Due Loans	3	18
Current Loans	8,978	10,036
Gross Loans	8,981	10,054
Non-accrual Loans	2	20
Loans 30-59 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	20,880	3,978
Loans 30-59 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	6,105	1,469
Loans 30-59 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	417	576
Loans 30-59 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	13,466	576
Loans 30-59 Days Past Due | SBA paycheck protection program
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0
Loans 30-59 Days Past Due | Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	890	700
Loans 30-59 Days Past Due | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0	645
Loans 30-59 Days Past Due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	2	12
Loans 60-89 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	513	8,556
Loans 60-89 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	499	3,914
Loans 60-89 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	13	1,034
Loans 60-89 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0	3,325
Loans 60-89 Days Past Due | SBA paycheck protection program
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0
Loans 60-89 Days Past Due | Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0	283
Loans 60-89 Days Past Due | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0	0
Loans 60-89 Days Past Due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	1	0
Loans equal to or greater than 90 days past due
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	8,095	6,956
Loans equal to or greater than 90 days past due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	5,592	4,158
Loans equal to or greater than 90 days past due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	607	265
Loans equal to or greater than 90 days past due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	1,351	1,735
Loans equal to or greater than 90 days past due | SBA paycheck protection program
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0
Loans equal to or greater than 90 days past due | Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	290	623
Loans equal to or greater than 90 days past due | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	255	169
Loans equal to or greater than 90 days past due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	0	6
Not Adversely Classified
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	3,032,370	2,531,440
Non-accrual loans not adversely classified	137	84
Not Adversely Classified | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	1,437,950	1,377,515
Not Adversely Classified | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	425,466	487,957
Not Adversely Classified | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	369,808	312,641
Not Adversely Classified | SBA paycheck protection program
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	453,084
Not Adversely Classified | Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	252,497	245,548
Not Adversely Classified | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	84,625	97,797
Not Adversely Classified | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross Loans	$ 8,940	$ 9,982