Loans, Allowance for Loan Losses and Credit Quality - Summary of Risk Category of Loans by Class of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 1,199,543	$ 909,856	$ 757,153
Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	1,195,353	888,407
Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	2,556	14,143
Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	1,634	7,306
Home Equity Lines of Credit
Financing Receivable Recorded Investment [Line Items]
Total loans	44,484	47,410
Home Equity Lines of Credit | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	44,356	46,994
Home Equity Lines of Credit | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		59
Home Equity Lines of Credit | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	128	357
Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	265,446	237,218
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	345,576	310,019
Construction and Land Development
Financing Receivable Recorded Investment [Line Items]
Total loans	143,751	113,526
Commercial Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	359,656	161,286	127,337
Commercial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	359,110	158,969
Commercial Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	332	1,482
Commercial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	214	835
Consumer Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	40,630	40,397	37,417
Consumer Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	39,875	39,564
Consumer Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	357	389
Consumer Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	398	444
Mortgage Loans on Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	754,773	660,763
Mortgage Loans on Real Estate | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	752,012	642,880
Mortgage Loans on Real Estate | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	1,867	12,213
Mortgage Loans on Real Estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	894	5,670
Mortgage Loans on Real Estate | Home Equity Lines of Credit
Financing Receivable Recorded Investment [Line Items]
Total loans	44,484		43,519
Mortgage Loans on Real Estate | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	265,446	237,218	196,142
Mortgage Loans on Real Estate | Residential Real Estate | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	264,049	232,017
Mortgage Loans on Real Estate | Residential Real Estate | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	902	3,589
Mortgage Loans on Real Estate | Residential Real Estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	495	1,612
Mortgage Loans on Real Estate | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	345,576	310,019	256,203
Mortgage Loans on Real Estate | Commercial Real Estate | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	345,074	298,980
Mortgage Loans on Real Estate | Commercial Real Estate | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	232	7,204
Mortgage Loans on Real Estate | Commercial Real Estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	270	3,835
Mortgage Loans on Real Estate | Construction and Land Development
Financing Receivable Recorded Investment [Line Items]
Total loans	143,751	113,526	$ 96,535
Mortgage Loans on Real Estate | Construction and Land Development | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	142,889	111,883
Mortgage Loans on Real Estate | Construction and Land Development | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	733	1,420
Mortgage Loans on Real Estate | Construction and Land Development | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 129	$ 223