Allowance For Loan Losses - Past Due and Non-Accrual Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 3,194,723	$ 2,568,562
Total Past Due Loans	18,318	19,490
Current Loans	3,176,405	2,549,072
Non-accrual loans	$ 21,335	$ 14,771
The ratio of non-accrual loans to total loans	0.67%	0.58%
Number of loans with short-term payment deferrals	1,130
Amount of short-term payment deferrals	$ 594,800
Percentage of loans on short term payment deferral	22.00%
Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 1,471,586	$ 1,394,179
Total Past Due Loans	10,039	9,541
Current Loans	1,461,547	1,384,638
Non-accrual loans	8,789	8,280
Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	454,455	501,227
Total Past Due Loans	2,021	1,875
Current Loans	452,434	499,352
Non-accrual loans	5,549	3,285
Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	404,008	317,477
Total Past Due Loans	5,295	5,636
Current Loans	398,713	311,841
Non-accrual loans	5,801	1,735
SBA Paycheck Protection Program
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	505,557	0
Total Past Due Loans	0
Current Loans	505,557
Non-accrual loans	0
Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	261,786	247,373
Total Past Due Loans	674	1,606
Current Loans	261,112	245,767
Non-accrual loans	473	411
Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	88,157	98,252
Total Past Due Loans	254	814
Current Loans	87,903	97,438
Non-accrual loans	705	1,040
Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	9,174	10,054
Total Past Due Loans	35	18
Current Loans	9,139	10,036
Non-accrual loans	18	20
Not Adversely Classified
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	3,153,690	2,531,440
Non-accrual loans not adversely classified	58	84
Not Adversely Classified | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	1,453,275	1,377,515
Not Adversely Classified | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	442,131	487,957
Not Adversely Classified | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	395,210	312,641
Not Adversely Classified | SBA Paycheck Protection Program
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	505,557
Not Adversely Classified | Residential mortgages
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	260,803	245,548
Not Adversely Classified | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	87,601	97,797
Not Adversely Classified | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	9,113	9,982
Loans 30-59 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	4,414	3,978
Loans 30-59 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	3,375	1,469
Loans 30-59 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	345	576
Loans 30-59 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	0	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	674	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	20	12
Loans 60-89 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	2,899	8,556
Loans 60-89 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	2,282	3,914
Loans 60-89 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	602	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	15	0
Loans equal to or greater than 90 days past due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	11,005	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	4,382	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	1,074	265
Loans equal to or greater than 90 days past due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	5,295	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	0	623
Loans equal to or greater than 90 days past due | Home equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	254	169
Loans equal to or greater than 90 days past due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 0	$ 6