Note 2 - Earnings Per Common Share - Computation of 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 available to common stockholders	$ 17,547	$ 19,885	$ 33,243	$ 43,305
Earnings allocated to participating securities	(46)	(53)	(89)	(98)
Income attributable to common stock	$ 17,501	$ 19,832	$ 33,154	$ 43,207
Weighted average common shares outstanding, including participating securities (in shares)	38,421	39,078	38,383	39,127
Weighted average participating securities (in shares)	(101)	(104)	(103)	(88)
Weighted average common shares outstanding (in shares)	38,320	38,974	38,280	39,039
Incremental shares from assumed conversions of options, performance units and restricted shares (in shares)	129	43	173	135
Weighted average common and equivalent shares outstanding (in shares)	38,449	39,017	38,453	39,174
Earnings per common share:
Basic (in dollars per share)	$ 0.46	$ 0.51	$ 0.87	$ 1.11
Diluted (in dollars per share)	$ 0.46	$ 0.51	$ 0.86	$ 1.1