STOCK-BASED COMPENSATION - Stock option and restricted stock option activity (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Option Shares
Treasury Stock, Common, Value	$ 723		$ 659
Options [Member]
Option Shares
Outstanding at the beginning of the period (in shares)	759	767
Granted (in shares)	160	151
Options Exercised/RSAs Vested (in shares)	(114)	(111)
Forfeited (in shares)	(18)	(16)
Expired (in shares)	(1)
Outstanding at the end of the period (in shares)	786	1,582
Restricted Stock Awards [Member]
Option Shares
Outstanding at the beginning of the period (in shares)	117	86
Granted (in shares)	122	65
Options Exercised/RSAs Vested (in shares)	(42)	(33)
Forfeited (in shares)	(2)	0
Expired (in shares)	0
Outstanding at the end of the period (in shares)	195	236
Share-based Compensation Arrangement , Share-based Payment Award, Number of Shares Re-purchased from Employees	15	11
Treasury Stock, Common, Value	$ 1,031	$ 659