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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net income available to common stockholders	$ 19,898	$ 27,406	$ 63,203	$ 88,127
Earnings allocated to participating securities	(63)	(67)	(160)	(217)
Income attributable to common stock	$ 19,835	$ 27,339	$ 63,043	$ 87,910
Weighted average common shares outstanding, including participating securities (in shares)	38,817	39,243	39,020	39,393
Weighted average participating securities (in shares)	(123)	(96)	(99)	(97)
Weighted average common shares outstanding (in shares)	38,694	39,147	38,921	39,296
Incremental shares from assumed conversions of options, performance units and restricted shares (in shares)	135	192	135	214
Weighted average common and equivalent shares outstanding (in shares)	38,829	39,339	39,056	39,510
Earnings per common share:
Basic (in dollars per share)	$ 0.51	$ 0.7	$ 1.62	$ 2.24
Diluted (in dollars per share)	$ 0.51	$ 0.7	$ 1.61	$ 2.23