Note 6 - EARNINGS PER SHARE - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
EARNINGS PER SHARE
Net Income (Loss)	$ 25,121	$ 28,425	$ 27,157	$ 29,294	$ 15,242	$ 23,624	$ 80,703	$ 68,160
Basic EPS	$ 1.50			$ 1.73			$ 4.82	$ 4.25
Diluted EPS	$ 1.49			$ 1.71			$ 4.79	$ 4.20
Weighted average common shares outstanding	16,717,303			16,900,968			16,731,847	16,030,371
Weighted average common shares issuable upon exercise of stock options and under the employee stock purchase plan (in shares)	130,648			209,723			131,356	213,550
Weighted average common and common equivalent shares outstanding	16,847,951			17,110,691			16,863,203	16,243,921