Composition of securities (Details) - USD ($) $ in Thousands	Mar. 31, 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	$ 19,299	$ 19,283
U.S. Government Agency notes	29,017	29,696
Municipal bonds	55,099	55,179
U.S. Government agencies and U.S. Government- sponsored enterprises	67,804	69,866
U.S. Government agencies	24,954	25,370
Corporate bonds	14,250	14,250
Total securities available-for-sale	210,423	213,644
Non-marketable securities
Federal Home Loan Bank of Boston stock	5,030	1,285
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Available-for-sale
U.S. Treasury
U.S. Government Agency notes	58	94
Municipal bonds
U.S. Government agencies and U.S. Government- sponsored enterprises	19	20
U.S. Government agencies
Corporate bonds
Total securities available-for-sale	77	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	1,820	2,150
U.S. Government Agency notes	2,231	2,636
Municipal bonds	6,900	8,641
U.S. Government agencies and U.S. Government- sponsored enterprises	7,273	8,011
U.S. Government agencies	3,039	3,434
Corporate bonds	1,639	1,476
Total securities available-for-sale	22,902	26,348
Non-marketable securities
Federal Home Loan Bank of Boston stock
Securities Financing Transaction, Fair Value [Member]
Available-for-sale
U.S. Treasury	17,479	17,133
U.S. Government Agency notes	26,844	27,154
Municipal bonds	48,199	46,538
U.S. Government agencies and U.S. Government- sponsored enterprises	60,550	61,875
U.S. Government agencies	21,915	21,936
Corporate bonds	12,611	12,774
Total securities available-for-sale	187,598	187,410
Mutual Funds	2,068	1,933
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 5,030	$ 1,285