OTHER COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Obligation to Repurchase Receivables Sold
OTHER COMMITMENTS AND CONTINGENCIES
Contingent liability	$ 305,000	$ 305,000
Other Liabilities And Accrued Expenses | Obligation to Repurchase Receivables Sold
OTHER COMMITMENTS AND CONTINGENCIES
Contingent liability	3,000,000.0	3,600,000
Recourse liability	0	0
Commitments to grant residential real estate loans - HarborOne Mortgage
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	35,029,000	57,916,000
Commitments to grant other loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	48,547,000	43,700,000
Unadvanced funds on home equity lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	260,376,000	251,759,000
Unadvanced funds on revolving lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	306,943,000	351,382,000
Unadvanced funds on construction loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 210,829,000	$ 262,945,000