Consolidated Statements of Changes in Shareholders’ Equity - USD ($) $ in Thousands	Total	Charitable Foundation	Blue Foundry Bank ESOP	Common Stock	Common Stock Charitable Foundation	Additional Paid-In Capital	Additional Paid-In Capital Charitable Foundation	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period at Dec. 31, 2019	$ 237,620		$ 0	$ 10		$ 822		$ 237,305	$ (517)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(31,506)							(31,506)
Purchase of common shares by the ESOP (2,281,800 shares)	0
Other comprehensive income	(514)								(514)
Balance at end of period at Dec. 31, 2020	205,600		0	10		822		205,799	(1,031)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(36,342)							(36,342)
Proceeds from stock issued during the period	273,598	$ 7,500		268	$ 7	273,330	$ 7,493
Purchase of common shares by the ESOP (2,281,800 shares)	(22,818)		(22,818)
ESOP shares committed to be released (91,272 shares)	1,274		913			361
Other comprehensive income	659								659
Balance at end of period at Dec. 31, 2021	$ 429,471		$ (21,905)	$ 285		$ 282,006		$ 169,457	$ (372)