Allowance For Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses to total loans ratio	1.33%	1.42%	1.33%	1.42%	1.31%
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 39,764	$ 33,729	$ 33,614	$ 33,849
Provision for loan losses	2,675	955	8,822	555
Recoveries	85	151	205	474
Less: Charge offs	200	484	317	527
Ending Balance	42,324	34,351	42,324	34,351
Allocated to loans individually evaluated for impairment	3,867	2,349	3,867	2,349
Allocated to loans collectively evaluated for impairment	38,457	32,002	38,457	32,002
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	20,861	17,826	18,338	18,014
Provision for loan losses	1,616	2	4,139	(186)
Recoveries	0	0	0	0
Less: Charge offs	0	0	0	0
Ending Balance	22,477	17,828	22,477	17,828
Allocated to loans individually evaluated for impairment	37	5	37	5
Allocated to loans collectively evaluated for impairment	22,440	17,823	22,440	17,823
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	10,235	10,403	9,129	10,493
Provision for loan losses	(345)	647	759	241
Recoveries	67	140	174	456
Less: Charge offs	194	459	299	459
Ending Balance	9,763	10,731	9,763	10,731
Allocated to loans individually evaluated for impairment	2,351	2,307	2,351	2,307
Allocated to loans collectively evaluated for impairment	7,412	8,424	7,412	8,424
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	6,161	3,452	4,149	3,307
Provision for loan losses	1,337	265	3,349	410
Recoveries	0	0	0	0
Less: Charge offs	0	0	0	0
Ending Balance	7,498	3,717	7,498	3,717
Allocated to loans individually evaluated for impairment	1,440	0	1,440	0
Allocated to loans collectively evaluated for impairment	6,058	3,717	6,058	3,717
Residential mortgages
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	1,598	1,184	1,195	1,160
Provision for loan losses	130	3	533	27
Recoveries	0	0	0	0
Less: Charge offs	0	0	0	0
Ending Balance	1,728	1,187	1,728	1,187
Allocated to loans individually evaluated for impairment	0	5	0	5
Allocated to loans collectively evaluated for impairment	1,728	1,182	1,728	1,182
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	636	627	536	629
Provision for loan losses	(26)	(1)	71	(5)
Recoveries	3	3	6	5
Less: Charge offs	0	0	0	0
Ending Balance	613	629	613	629
Allocated to loans individually evaluated for impairment	0	0	0	0
Allocated to loans collectively evaluated for impairment	613	629	613	629
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	273	237	267	246
Provision for loan losses	(37)	39	(29)	68
Recoveries	15	8	25	13
Less: Charge offs	6	25	18	68
Ending Balance	245	259	245	259
Allocated to loans individually evaluated for impairment	39	32	39	32
Allocated to loans collectively evaluated for impairment	$ 206	$ 227	$ 206	227
General reserve factors related primarily to economic weakness
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses				5,200
classified and impaired loans
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses				2,300
loan growth and other factors
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses				$ 1,300

Allowance for Loan and Lease Losses to Total Loans, Ratio

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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