Composition of securities (Details) - USD ($) $ in Thousands	Jun. 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	$ 19,250	$ 15,301
U.S. Government Agency notes	31,301	31,623
Municipal bonds	55,339	46,469
U.S. Government agencies and U.S. Government- sponsored enterprises	77,339	74,703
U.S. Government agencies	24,531	20,948
Corporate bonds	13,750	12,250
Total securities available-for-sale	221,510	201,294
Non-marketable securities
Federal Home Loan Bank of Boston stock	945	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	128	237
Municipal bonds	2	1,557
U.S. Government agencies and U.S. Government- sponsored enterprises	52	643
U.S. Government agencies		135
Corporate bonds	10	158
Total securities available-for-sale	192	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	1,578	182
U.S. Government Agency notes	1,711	256
Municipal bonds	7,074	204
U.S. Government agencies and U.S. Government- sponsored enterprises	5,924	805
U.S. Government agencies	1,979	185
Corporate bonds	326	8
Total securities available-for-sale	18,592	1,640
Non-marketable securities
Federal Home Loan Bank of Boston stock
Securities Financing Transaction, Fair Value [Member]
Available-for-sale
U.S. Treasury	17,672	15,131
U.S. Government Agency notes	29,718	31,604
Municipal bonds	48,267	47,822
U.S. Government agencies and U.S. Government- sponsored enterprises	71,467	74,541
U.S. Government agencies	22,552	20,898
Corporate bonds	13,434	12,400
Total securities available-for-sale	203,110	202,396
Mutual fund	1,672	901
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 945	$ 1,397