Composition of securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale, Cost of Security Sold or Transferred, Method, Specific Identification [Member]
Available-for-sale
U.S. Treasury	$ 19,283	$ 15,301
U.S. Government Agency notes	29,696	31,623
Municipal bonds	55,179	46,469
U.S. Government agencies and U.S. Government- sponsored enterprises	69,866	74,703
U.S. Government agencies	25,370	20,948
Corporate bonds	14,250	12,250
Total securities available-for-sale	213,644	201,294
Non-marketable securities
Federal Home Loan Bank of Boston stock	1,285	1,397
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Available-for-sale
U.S. Treasury		12
U.S. Government Agency notes	94	237
Municipal bonds		1,557
U.S. Government agencies and U.S. Government- sponsored enterprises	20	643
U.S. Government agencies		135
Corporate bonds		158
Total securities available-for-sale	114	2,742
Non-marketable securities
Federal Home Loan Bank of Boston stock
Accumulated Net Unrealized Investment Gain Loss 1 [Member]
Available-for-sale
U.S. Treasury	2,150	182
U.S. Government Agency notes	2,636	256
Municipal bonds	8,641	204
U.S. Government agencies and U.S. Government- sponsored enterprises	8,011	805
U.S. Government agencies	3,434	185
Corporate bonds	1,476	8
Total securities available-for-sale	26,348	1,640
Non-marketable securities
Federal Home Loan Bank of Boston stock
Securities Financing Transaction, Fair Value [Member]
Available-for-sale
U.S. Treasury	17,133	15,131
U.S. Government Agency notes	27,154	31,604
Municipal bonds	46,538	47,822
U.S. Government agencies and U.S. Government- sponsored enterprises	61,875	74,541
U.S. Government agencies	21,936	20,898
Corporate bonds	12,774	12,400
Total securities available-for-sale	187,410	202,396
Mutual fund	1,933	901
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 1,285	$ 1,397