Note 6 - Earnings per Common Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net income	$ 70,373	$ 110,354	$ 85,428
Denominator:
Basic earnings per common share - weighted-average shares (in shares)	81,272	81,692	82,872
Effect of dilutive stock options (in shares)	141	267	536
Diluted earnings per common share - weighted-average shares and assumed conversions (in shares)	81,413	81,959	83,408
Basic earnings per common share (in dollars per share)	$ 0.87	$ 1.35	$ 1.03
Diluted earnings per common share (in dollars per share)	$ 0.86	$ 1.35	$ 1.02