EARNINGS PER SHARE - (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Shares
Basic (in shares)	17,821	17,527	17,795	17,502
Effect of dilutive stock options (in shares)	748	681	761	612
Diluted (in shares)	18,569	18,208	18,556	18,114
Per Share Amount
Basic (in dollars per share)	$ 0.52	$ 0.41	$ 0.90	$ 0.69
Effect of dilutive stock options (in dollars per share)	(0.02)	(0.01)	(0.04)	(0.02)
Diluted (in dollars per share)	$ 0.50	$ 0.40	$ 0.86	$ 0.67