OTHER COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
OTHER COMMITMENTS AND CONTINGENCIES
Compensation to employees		$ 5,092,000
Employee Agreements
OTHER COMMITMENTS AND CONTINGENCIES
Employee agreement term	5 years
Total compensation to employees	$ 2,200,000
Compensation to employees	1,700,000	509,000
Obligation to Repurchase Receivables Sold | Maximum
OTHER COMMITMENTS AND CONTINGENCIES
Reserve	1,300,000	1,600,000
Other Liabilities And Accrued Expenses | Obligation to Repurchase Receivables Sold
OTHER COMMITMENTS AND CONTINGENCIES
Reserve	834,000	757,000
Recourse liability	0	0
Commitments to grant loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	94,157,000	47,958,000
Unadvanced funds on home equity lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	157,867,000	138,227,000
Unadvanced funds on revolving lines of credit
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	147,047,000	125,257,000
Unadvanced funds on construction loans
OTHER COMMITMENTS AND CONTINGENCIES
Financial instruments committed contract amount	$ 112,158,000	$ 111,333,000