RIGHT-OF-USE ASSETS AND OPERATING LEASE LIABILITIES - OPERATING LEASE EXPENSE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Operating lease expense:
Total operating lease expense	$ 1,754	$ 1,773	$ 3,521	$ 3,538
Cash paid for amounts included in the measurement of operating lease liabilities	$ 1,793	1,794	3,630	3,577
Short-term lease payments not included in the measurement of lease liabilities		12	$ 4	26
Weighted average remaining term in years	7 years 11 months 26 days		7 years 11 months 26 days		8 years 7 days
Weighted average discount rate	3.55%		3.55%		3.46%
Related Party
Operating lease expense:
Variable lease expense	$ 1,183	1,156	$ 2,371	2,314
Fixed lease expense	23	10	47	18
Third Party
Operating lease expense:
Variable lease expense	180	211	361	435
Fixed lease expense	$ 368	384	738	745
Short-term lease expense		$ 12	$ 4	$ 26