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Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commercial lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	$ 238,361	$ 224,370
Revolving home equity lines
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	189,971	177,678
Undisbursed construction loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	46,229	35,322
Personal and other lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	14,109	11,758
Standby letters of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	2,636	4,074
Total commitments and standby letters of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	$ 491,306	453,202
Percentage of commitments expiring in 2018	35.00%
Percentage of commitments expiring between 2019 and 2025	51.00%
Percentage of commitments expiring 2026 and thereafter	14.00%
Total commitments and standby letters of credit | Interest Payable and Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for off-balance sheet commitments	$ 958	$ 958

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Loan Commitments And Standby Letters Of Credit, Percentage Expiring, After Year Eight

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Loan Commitments and Standby Letters of Credit, Percentage Expiring in Next Twelve Months

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Loan Commitments And Standby Letters of Credit, Percentage Expiring In Year Two Through Eight

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Off-balance Sheet Arrangements, Liabilities, Current Exposure

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