Note 11 - Earnings Per Common Share - Earnings Per Common Share and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net income (numerator)	$ 35,462	$ 40,248	$ 71,879	$ 80,699
Weighted average number of common shares outstanding - basic (denominator) (in shares)	26,680	26,648	26,677	26,753
Basic earnings per common share (in dollars per share)	$ 1.33	$ 1.51	$ 2.69	$ 3.02
Add common stock equivalents for options (in shares)	1	0	1	3
Weighted average number of common shares outstanding - diluted (denominator) (in shares)	26,681	26,648	26,678	26,756
Diluted earnings per common share (in dollars per share)	$ 1.33	$ 1.51	$ 2.69	$ 3.02