Note 2 - Earnings per Common Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Net income	$ 13,598	$ 21,874	$ 22,502	$ 25,646	$ 31,661	$ 27,533	$ 57,974	$ 84,840
Basic earnings per common share - weighted-average shares (in shares)	81,306			81,061			81,260	81,889
Effect of dilutive stock options (in shares)	148			286			154	266
Diluted earnings per common share - weighted-average shares and assumed conversions (in shares)	81,454			81,347			81,414	82,155
Basic earnings per common share (in dollars per share)	$ 0.17			$ 0.32			$ 0.71	$ 1.04
Diluted earnings per common share (in dollars per share)	$ 0.17			$ 0.32			$ 0.71	$ 1.03