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
	Mar. 31, 2023	Mar. 31, 2022
Net income available to common stockholders	$ 23,420	$ 29,872
Earnings allocated to participating securities	(44)	(80)
Income attributable to common stock	$ 23,376	$ 29,792
Weighted average common shares outstanding, including participating securities (in shares)	39,178	39,560
Weighted average participating securities (in shares)	(74)	(107)
Weighted average common shares outstanding (in shares)	39,104	39,453
Incremental shares from assumed conversions of options, performance units and restricted shares (in shares)	197	274
Weighted average common and equivalent shares outstanding (in shares)	39,301	39,727
Basic (in dollars per share)	$ 0.60	$ 0.76
Diluted (in dollars per share)	$ 0.59	$ 0.75