EARNINGS PER SHARE - Computation of basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
EARNINGS PER SHARE
Net income for common shareholders	$ 12,747	$ 14,421	$ 35,049	$ 36,143
Weighted-average shares (thousands)
Basic weighted-average shares outstanding	24,345	24,432	24,445	24,462
Dilutive effect of outstanding stock options and unvested restricted stock awards	119	112	107	110
Diluted weighted-average shares outstanding	24,464	24,544	24,552	24,572
Earnings per share:
Basic	$ 0.52	$ 0.59	$ 1.43	$ 1.48
Diluted	$ 0.52	$ 0.59	$ 1.43	$ 1.47