EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	200,000	600,000
Basic earnings per share [Abstract]
Net income	$ 26,257	$ 24,403
Income attributable to unvested stock-based compensation awards	(138)	(89)
Income available to common shareholders	$ 26,119	$ 24,314
Weighted-average common shares outstanding - basic (in shares)	45,284,000	43,863,000
Basic earnings per share (in dollars per share)	$ 0.58	$ 0.55
Diluted earnings per share [Abstract]
Net income	$ 26,257	$ 24,403
Income attributable to unvested stock-based compensation awards	(138)	(89)
Income available to common shareholders	$ 26,119	$ 24,314
Weighted-average common shares outstanding - basic (in shares)	45,284,000	43,863,000
Assumed exercise of stock options (in shares)	703,000	333,000
Weighted-average common shares outstanding - diluted (in shares)	45,987,000	44,196,000
Net income per diluted common share (in dollars per share)	$ 0.57	$ 0.55
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