EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	600,000	500,000	600,000	500,000
Basic earnings per share [Abstract]
Net income	$ 35,248	$ 45,015	$ 75,382	$ 86,961
Income attributable to unvested stock-based compensation awards	(127)	(146)	(264)	(255)
Income available to common shareholders	$ 35,121	$ 44,869	$ 75,118	$ 86,706
Weighted-average common shares outstanding - basic (in shares)	52,487,000	51,659,000	52,262,000	51,590,000
Basic earnings per share (in dollars per share)	$ 0.67	$ 0.87	$ 1.44	$ 1.68
Diluted earnings per share [Abstract]
Net income	$ 35,248	$ 45,015	$ 75,382	$ 86,961
Income attributable to unvested stock-based compensation awards	(127)	(146)	(264)	(255)
Income available to common shareholders	$ 35,121	$ 44,869	$ 75,118	$ 86,706
Weighted-average common shares outstanding - basic (in shares)	52,487,000	51,659,000	52,262,000	51,590,000
Assumed exercise of stock options (in shares)	339,000	529,000	372,000	535,000
Weighted-average common shares outstanding - diluted (in shares)	52,826,000	52,188,000	52,634,000	52,125,000
Diluted earnings per share (in dollars per share)	$ 0.66	$ 0.86	$ 1.43	$ 1.66
Stock Repurchase Program [Abstract]
Number of common shares authorized to be repurchased (in shares)					2,600,000	2,500,000
Number of common shares repurchased (in shares)			0	0