OTHER COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Commitments to grant residential real estate loans - HarborOne Mortgage
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 48,624	$ 35,029
Commitments to grant other loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	39,967	48,547
Unadvanced funds on home equity lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	264,888	260,376
Unadvanced funds on revolving lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	283,982	306,943
Unadvanced funds on construction loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 175,514	$ 210,829