EARNINGS PER SHARE - (Details) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Shares
Basic (in shares)	17,886	17,616	17,826	17,541
Effect of dilutive stock options (in shares)	745	782	756	671
Diluted (in shares)	18,631	18,398	18,582	18,212
Per Share Amount
Basic (in dollars per share)	$ 0.61	$ 0.51	$ 1.51	$ 1.20
Effect of dilutive stock options (in dollars per share)	(0.03)	(0.02)	(0.07)	(0.04)
Diluted (in dollars per share)	$ 0.58	$ 0.49	$ 1.44	$ 1.16