EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	600,000	300,000
Basic earnings per share [Abstract]
Net income	$ 24,403	$ 22,297
Income attributable to unvested stock-based compensation awards	(89)	(100)
Income available to common shareholders	$ 24,314	$ 22,197
Weighted-average common shares outstanding - basic (in shares)	43,863,000	40,659,000
Basic earnings per share (in dollars per share)	$ 0.55	$ 0.55
Diluted earnings per share [Abstract]
Net income	$ 24,403	$ 22,297
Income attributable to unvested stock-based compensation awards	(89)	(100)
Income available to common shareholders	$ 24,314	$ 22,197
Weighted-average common shares outstanding - basic (in shares)	43,863,000	40,659,000
Assumed exercise of stock options (in shares)	333,000	405,000
Weighted-average common shares outstanding - diluted (in shares)	44,196,000	41,064,000
Diluted earnings per share (in dollars per share)	$ 0.55	$ 0.54
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