EARNINGS PER SHARE - (Details) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Shares
Basic (in shares)	17,770	17,477
Effect of dilutive stock options (in shares)	940	544
Diluted (in shares)	18,710	18,021
Per Share Amount
Basic (in dollars per share)	$ 0.38	$ 0.28
Effect of dilutive stock options (in dollars per share)	(0.02)	(0.01)
Diluted (in dollars per share)	$ 0.36	$ 0.27