REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 7,383	$ 6,418	$ 21,077	$ 18,497
Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue	3,737	3,133	10,593	9,026
Products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue	3,646	3,285	10,484	9,471
Trust management fees
Disaggregation of Revenue [Line Items]
Revenue	3,403	3,256	10,052	9,193
Financial services fees
Disaggregation of Revenue [Line Items]
Revenue	465	276	1,283	867
Interchange fees
Disaggregation of Revenue [Line Items]
Revenue	1,882	1,709	5,509	4,910
Customer deposit fees
Disaggregation of Revenue [Line Items]
Revenue	1,363	937	3,542	2,836
Other customer service fees
Disaggregation of Revenue [Line Items]
Revenue	$ 270	$ 240	$ 691	$ 691