Composition of securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale, Cost of Security Sold or Transferred, Method, Specific Identification [Member]
Available-for-sale
U.S. Treasury	$ 19,315	$ 19,283
U.S. Government Agency notes	27,999	29,696
Municipal bonds	51,037	55,179
U.S. Government agencies and U.S. Government- sponsored enterprises	65,811	69,866
U.S. Government agencies	24,414	25,370
Corporate bonds	14,250	14,250
Total securities available-for-sale	202,826	213,644
Non-marketable securities
Federal Home Loan Bank of Boston stock	1,488	1,285
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Available-for-sale
U.S. Treasury
U.S. Government Agency notes	5	94
Municipal bonds
U.S. Government agencies and U.S. Government- sponsored enterprises	18	20
U.S. Government agencies
Corporate bonds
Total securities available-for-sale	23	114
Non-marketable securities
Federal Home Loan Bank of Boston stock
Accumulated Net Unrealized Investment Gain Loss 1 [Member]
Available-for-sale
U.S. Treasury	2,070	2,150
U.S. Government Agency notes	2,488	2,636
Municipal bonds	7,375	8,641
U.S. Government agencies and U.S. Government- sponsored enterprises	7,760	8,011
U.S. Government agencies	3,589	3,434
Corporate bonds	2,090	1,476
Total securities available-for-sale	25,372	26,348
Non-marketable securities
Federal Home Loan Bank of Boston stock
Securities Financing Transaction, Fair Value [Member]
Available-for-sale
U.S. Treasury	17,245	17,133
U.S. Government Agency notes	25,516	27,154
Municipal bonds	43,662	46,538
U.S. Government agencies and U.S. Government- sponsored enterprises	58,069	61,875
U.S. Government agencies	20,825	21,936
Corporate bonds	12,160	12,774
Total securities available-for-sale	177,477	187,410
Mutual fund	2,020	1,933
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 1,488	$ 1,285