EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
EARNINGS PER SHARE
Net income	$ 13,220	$ 5,049	$ 22,463	$ 10,234
Basic
Weighted average basic shares outstanding	21,867	21,751	21,835	21,738
Earnings per share (in dollars per share)	$ 0.60	$ 0.23	$ 1.03	$ 0.47
Diluted
Dilutive effect of stock-based awards (in shares)	157	139	156	136
Weighted average diluted shares outstanding	22,024	21,890	21,991	21,874
Earnings per share (in dollars per share)	$ 0.60	$ 0.23	$ 1.02	$ 0.47
Anti-dilutive shares excluded from calculation	58	115	76	113