CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Wellesley Bancorp Inc	North Mark Merger	Common Stock	Common Stock Wellesley Bancorp Inc	Common Stock North Mark Merger	Additional Paid-In Capital	Additional Paid-In Capital Wellesley Bancorp Inc	Additional Paid-In Capital North Mark Merger	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income / (Loss)
Beginning balance at Dec. 31, 2019	$ 286,561	$ (347)			$ 5,401			$ 136,766			$ 146,875	$ (347)	$ (2,481)
Accounting Standards Update [Extensible List]	ASU 2020-04				ASU 2020-04			ASU 2020-04			ASU 2020-04		ASU 2020-04
Net income	$ 31,959										$ 31,959
Other comprehensive income (loss)	4,915												$ 4,915
Share based compensation and other share-based activity	4,564				$ 23			$ 4,541
Dividends declared	(13,083)										(13,083)
Common stock issued for merger			$ 87,163			$ 1,503			$ 85,660
Ending balance at Dec. 31, 2020	401,732				6,927			226,967			165,404		2,434
Net income	54,024										54,024
Other comprehensive income (loss)	(3,644)												(3,644)
Share based compensation and other share-based activity	2,279				41			2,238
Dividends declared	(16,554)										(16,554)
Ending balance at Dec. 31, 2021	437,837				6,968			229,205			202,874		(1,210)
Net income	52,909										52,909
Other comprehensive income (loss)	(19,589)												(19,589)
Share based compensation and other share-based activity	1,959				39			1,920
Dividends declared	(18,414)										(18,414)
Common stock issued for merger				$ 62,850			$ 789			$ 62,061
Ending balance at Dec. 31, 2022	$ 517,552				$ 7,796			$ 293,186			$ 237,369		$ (20,799)