EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	200,000	0	100,000	300,000
Basic earnings per share [Abstract]
Net income	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Income attributable to unvested stock-based compensation awards	(164)	(157)	(387)	(398)
Income available to common shareholders	$ 35,079	$ 27,003	$ 78,304	$ 77,022
Weighted-average common shares outstanding - basic (in shares)	50,703,000	44,184,000	48,189,000	44,023,000
Basic earnings per share (in dollars per share)	$ 0.69	$ 0.61	$ 1.62	$ 1.75
Diluted earnings per share [Abstract]
Net income	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Income attributable to unvested stock-based compensation awards	(164)	(157)	(387)	(398)
Income available to common shareholders	$ 35,079	$ 27,003	$ 78,304	$ 77,022
Weighted-average common shares outstanding - basic (in shares)	50,703,000	44,184,000	48,189,000	44,023,000
Assumed exercise of stock options (in shares)	585,000	394,000	640,000	359,000
Weighted-average common shares outstanding - diluted (in shares)	51,288,000	44,578,000	48,829,000	44,382,000
Diluted earnings per share (in dollars per share)	$ 0.68	$ 0.61	$ 1.60	$ 1.74
Stock Repurchase Program [Abstract]
Number of common shares authorized to be repurchased (in shares)					2,200,000
Number of common shares repurchased (in shares)			0