Allowance For Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses to total loans ratio	1.48%	1.41%	1.31%
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 33,614	$ 33,849
Provision for loan losses	6,147	(400)
Recoveries	120	323
Less: Charge offs	117	43
Ending Balance	39,764	33,729
Allocated to loans individually evaluated for impairment	2,448	2,144
Allocated to loans collectively evaluated for impairment	37,316	31,585
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	18,338	18,014
Provision for loan losses	2,523	(188)
Recoveries	0	0
Less: Charge offs	0	0
Ending Balance	20,861	17,826
Allocated to loans individually evaluated for impairment	29	6
Allocated to loans collectively evaluated for impairment	20,832	17,820
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	9,129	10,493
Provision for loan losses	1,104	(406)
Recoveries	107	316
Less: Charge offs	105	0
Ending Balance	10,235	10,403
Allocated to loans individually evaluated for impairment	908	2,112
Allocated to loans collectively evaluated for impairment	9,327	8,291
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	4,149	3,307
Provision for loan losses	2,012	145
Recoveries	0	0
Less: Charge offs	0	0
Ending Balance	6,161	3,452
Allocated to loans individually evaluated for impairment	1,473	0
Allocated to loans collectively evaluated for impairment	4,688	3,452
Residential mortgages
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	1,195	1,160
Provision for loan losses	403	24
Recoveries	0	0
Less: Charge offs	0	0
Ending Balance	1,598	1,184
Allocated to loans individually evaluated for impairment	0	12
Allocated to loans collectively evaluated for impairment	1,598	1,172
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	536	629
Provision for loan losses	97	(4)
Recoveries	3	2
Less: Charge offs	0	0
Ending Balance	636	627
Allocated to loans individually evaluated for impairment	0	0
Allocated to loans collectively evaluated for impairment	636	627
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	267	246
Provision for loan losses	8	29
Recoveries	10	5
Less: Charge offs	12	43
Ending Balance	273	237
Allocated to loans individually evaluated for impairment	38	14
Allocated to loans collectively evaluated for impairment	$ 235	$ 223

Allowance for Loan and Lease Losses to Total Loans, Ratio

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- Definition

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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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- Definition

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

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