MORTGAGE SERVICING RIGHTS - Balance of loans serviced for others and fair value of mortgage servicing rights (Details) - Balance of loans serviced for others and fair value of mortgage servicing rights - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Residential mortgage loans serviced for others	$ 110,933	$ 106,255
Fair value of mortgage servicing rights	$ 613	$ 813