EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
EARNINGS PER SHARE
Weighted-average anti-dilutive stock options outstanding		100,000	600,000
Basic earnings per share
Net income	$ 188,081	$ 189,694	$ 164,676
Income attributable to unvested stock-based compensation awards	(533)	(445)	(514)
Income available to common shareholders	$ 187,548	$ 189,249	$ 164,162
Weighted-average common shares outstanding	53,896,000	53,977,000	52,969,000
Basic earnings per share	$ 3.48	$ 3.51	$ 3.10
Diluted earnings per share
Net income	$ 188,081	$ 189,694	$ 164,676
Income attributable to unvested stock-based compensation awards	(533)	(445)	(514)
Income available to common shareholders	$ 187,548	$ 189,249	$ 164,162
Weighted-average common shares outstanding	53,896,000	53,977,000	52,969,000
Assumed exercise of stock options	312,000	423,000	352,000
Weighted-average common shares outstanding - diluted	54,208,000	54,400,000	53,321,000
Diluted earnings per share	$ 3.46	$ 3.48	$ 3.08
Cash dividends declared per share (in dollars per share)	$ 1.74	$ 1.70	$ 1.66
Stock Repurchase Program
Number of common shares authorized to be repurchased (in shares)	2,697,000	2,697,000
Number of common shares repurchased (in shares)	250,000