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Loans and Allowance for Credit Losses on Loans - Loans Outstanding and Aging Analysis (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	$ 2,102,796,000		$ 2,102,796,000		$ 2,092,546,000
Loans past due more than 90 days still accruing	0		0		0
Financing receivable, nonaccrual, earning interest on cash basis	0		0		0
Financing receivable, nonaccrual, interest income	0	$ 0	0	$ 0
Financing receivable, accrued interest, writeoff			14,000	$ 8,000
Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	2,102,796,000		2,102,796,000		2,092,546,000
Non-accrual loans	2,112,000		2,112,000		2,432,000
Non-accrual loans with no allowance	2,112,000		2,112,000		2,432,000
Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	2,362,000		2,362,000		1,342,000
30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	546,000		546,000		420,000
60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	528,000		528,000		244,000
90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,288,000		1,288,000		678,000
Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	2,100,434,000		2,100,434,000		2,091,204,000
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	183,157,000		183,157,000		173,547,000
Commercial loans | Commercial and industrial | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	183,157,000		183,157,000		173,547,000
Non-accrual loans	0		0		0
Non-accrual loans with no allowance	0		0		0
Commercial loans | Commercial and industrial | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	436,000		436,000		267,000
Commercial loans | Commercial and industrial | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		3,000
Commercial loans | Commercial and industrial | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	436,000		436,000		0
Commercial loans | Commercial and industrial | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		264,000
Commercial loans | Commercial and industrial | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	182,721,000		182,721,000		173,280,000
Commercial real estate loans | Commercial owner-occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	344,951,000		344,951,000		354,877,000
Commercial real estate loans | Commercial owner-occupied | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	344,951,000		344,951,000		354,877,000
Non-accrual loans	457,000		457,000		1,563,000
Non-accrual loans with no allowance	457,000		457,000		1,563,000
Commercial real estate loans | Commercial owner-occupied | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	164,000		164,000		0
Commercial real estate loans | Commercial owner-occupied | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Commercial owner-occupied | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Commercial owner-occupied | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	164,000		164,000		0
Commercial real estate loans | Commercial owner-occupied | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	344,787,000		344,787,000		354,877,000
Commercial real estate loans | Commercial non-owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,196,158,000		1,196,158,000		1,191,889,000
Commercial real estate loans | Commercial non-owner occupied | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,196,158,000		1,196,158,000		1,191,889,000
Non-accrual loans	906,000		906,000		0
Non-accrual loans with no allowance	906,000		906,000		0
Commercial real estate loans | Commercial non-owner occupied | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,277,000		1,277,000		0
Commercial real estate loans | Commercial non-owner occupied | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	371,000		371,000		0
Commercial real estate loans | Commercial non-owner occupied | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Commercial non-owner occupied | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	906,000		906,000		0
Commercial real estate loans | Commercial non-owner occupied | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,194,881,000		1,194,881,000		1,191,889,000
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	108,986,000		108,986,000		114,373,000
Commercial real estate loans | Construction | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	108,986,000		108,986,000		114,373,000
Non-accrual loans	0		0		0
Non-accrual loans with no allowance	0		0		0
Commercial real estate loans | Construction | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Construction | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Construction | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Construction | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Commercial real estate loans | Construction | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	108,986,000		108,986,000		114,373,000
Residential loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	85,587,000		85,587,000		88,748,000
Residential loans | Home equity | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	85,587,000		85,587,000		88,748,000
Non-accrual loans	749,000		749,000		778,000
Non-accrual loans with no allowance	749,000		749,000		778,000
Residential loans | Home equity | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	433,000		433,000		977,000
Residential loans | Home equity | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	124,000		124,000		319,000
Residential loans | Home equity | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	91,000		91,000		244,000
Residential loans | Home equity | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	218,000		218,000		414,000
Residential loans | Home equity | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	85,154,000		85,154,000		87,771,000
Residential loans | Other residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	118,646,000		118,646,000		112,123,000
Residential loans | Other residential | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	118,646,000		118,646,000		112,123,000
Non-accrual loans	0		0		0
Non-accrual loans with no allowance	0		0		0
Residential loans | Other residential | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		93,000
Residential loans | Other residential | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		93,000
Residential loans | Other residential | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Residential loans | Other residential | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Residential loans | Other residential | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	118,646,000		118,646,000		112,030,000
Consumer loans | Installment and other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	65,311,000		65,311,000		56,989,000
Consumer loans | Installment and other consumer loans | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	65,311,000		65,311,000		56,989,000
Non-accrual loans	0		0		91,000
Non-accrual loans with no allowance	0		0		91,000
Consumer loans | Installment and other consumer loans | Total past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	52,000		52,000		5,000
Consumer loans | Installment and other consumer loans | 30-59 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	51,000		51,000		5,000
Consumer loans | Installment and other consumer loans | 60-89 days past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,000		1,000		0
Consumer loans | Installment and other consumer loans | 90 days or more past due | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	0		0		0
Consumer loans | Installment and other consumer loans | Current | Financial asset, other than financial asset acquired with credit deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	$ 65,259,000		$ 65,259,000		$ 56,984,000

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