OTHER COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Commitments to grant residential real estate loans - HarborOne Mortgage
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 122,378	$ 142,781
Commitments to grant other loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	174,272	27,029
Unadvanced funds on home equity lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	242,496	211,120
Unadvanced funds on revolving lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	329,153	223,110
Unadvanced funds on construction loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 338,792	$ 194,101