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
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Residential mortgage loans serviced for others	$ 106,868	$ 111,378
Fair value of mortgage servicing rights	$ 818		$ 951