EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic and Diluted Earnings per Share [Line Items]
Net income from continuing operations	$ 45,259	$ (19,082)	$ 109	$ 18,584	$ 12,035	$ 11,628	$ 3,435	$ 22,020	$ 44,870	$ 49,118	$ 85,320
Weighted-average common shares outstanding (in shares)									25,103,720	25,335,706	25,047,405
Weighted-average common shares, diluted (in shares)									25,640,604	25,804,678	25,235,996
Earnings per common share from continuing operations, basic (in dollars per share)	$ 1.81	$ (0.77)	$ 0.00	$ 0.73	$ 0.46	$ 0.46	$ 0.13	$ 0.87	$ 1.79	$ 1.94	$ 3.41
Earnings per common share from continuing operations, diluted (in dollars per share)	1.78	(0.77)	0.00	0.72	0.46	0.45	0.13	0.86	1.75	1.90	3.38
Earnings per common share from discontinued operations, basic (in dollars per share)	0.03	0.05	0.11	0.05	0.00	0.03	(0.01)	0.02	0.24	0.03	0.15
Earnings per common share from discontinued operations, diluted (in dollars per share)	$ 0.03	$ 0.05	$ 0.11	$ 0.05	$ 0.00	$ 0.03	$ (0.01)	$ 0.02	0.24	0.03	0.15
Earnings per common share, basic (in dollars per share)									2.03	1.97	3.56
Earnings per common share, diluted (in dollars per share)									$ 1.99	$ 1.93	$ 3.53
Awards excluded from diluted calculation (in shares)									0	0	343,390
Restricted Stock Awards
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of restricted stock awards (in shares)									250,530	155,059	122,840
Stock Options
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of restricted stock awards (in shares)									286,354	313,913	65,751