Composition of securities (Details) - USD ($) $ in Thousands	Sep. 30, 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	$ 19,266	$ 15,301
U.S. Government Agency notes	30,552	31,623
Municipal bonds	55,260	46,469
U.S. Government agencies and U.S. Government- sponsored enterprises	72,163	74,703
U.S. Government agencies	25,925	20,948
Corporate bonds	14,250	12,250
Total securities available-for-sale	217,416	201,294
Non-marketable securities
Federal Home Loan Bank of Boston stock	1,487	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	114	237
Municipal bonds		1,557
U.S. Government agencies and U.S. Government- sponsored enterprises	30	643
U.S. Government agencies		135
Corporate bonds		158
Total securities available-for-sale	144	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	2,289	182
U.S. Government Agency notes	2,742	256
Municipal bonds	10,650	204
U.S. Government agencies and U.S. Government- sponsored enterprises	8,713	805
U.S. Government agencies	3,334	185
Corporate bonds	671	8
Total securities available-for-sale	28,399	1,640
Non-marketable securities
Federal Home Loan Bank of Boston stock
Securities Financing Transaction, Fair Value [Member]
Available-for-sale
U.S. Treasury	16,977	15,131
U.S. Government Agency notes	27,924	31,604
Municipal bonds	44,610	47,822
U.S. Government agencies and U.S. Government- sponsored enterprises	63,480	74,541
U.S. Government agencies	22,591	20,898
Corporate bonds	13,579	12,400
Total securities available-for-sale	189,161	202,396
Mutual fund	1,882	901
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 1,487	$ 1,397