Loans Composition of Net Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 766,050		$ 670,244
Allowance for loan losses	(7,691)	$ (6,888)	(6,122)	$ (5,808)	$ (5,676)	$ (5,739)
Net deferred loan (fees) costs	(536)		1,043
Net loans	757,823		665,165
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	182,935		192,125
Allowance for loan losses	(1,600)	(1,590)	(1,392)	(1,409)	(1,396)	(1,368)
Construction real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	49,668		69,617
Allowance for loan losses	(669)	(594)	(774)	(689)	(646)	(617)
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	317,985		289,883
Allowance for loan losses	(4,145)	(3,832)	(3,178)	(3,167)	(3,011)	(2,933)
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	114,868		47,699
Allowance for loan losses	(492)	(491)	(394)	(326)	(313)	(354)
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,833		3,562
Allowance for loan losses	(17)	(23)	(23)	(25)	(23)	(23)
Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	97,761		67,358
Allowance for loan losses	$ (212)	$ (79)	$ (76)	$ (78)	$ (33)	$ (82)