Commitments, Contingencies and Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) payment	Dec. 31, 2019 USD ($)
Other Commitments [Line Items]
Commitments to originate loans	$ 22,957	$ 25,930
Commitments to sell residential mortgage loans	3,493	1,696
Letters of credit	28,038	25,284
Residential mortgages
Other Commitments [Line Items]
Commitments to originate residential mortgages loans for sale	$ 3,121	1,095
Early payment default period | payment	4
Commercial real estate
Other Commitments [Line Items]
Unadvanced portions	$ 14,935	20,486
Commercial and industrial
Other Commitments [Line Items]
Unadvanced portions	530,525	472,419
Commercial and residential construction
Other Commitments [Line Items]
Unadvanced portions	228,309	294,744
Home equity
Other Commitments [Line Items]
Unadvanced portions	118,686	113,387
Consumer Loan
Other Commitments [Line Items]
Unadvanced portions	$ 4,269	$ 4,209