Note 7 - Net Income Per Share - Net Income Per Share Basic and Diluted (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	$ 100,366	$ 99,504	$ 192,907	$ 209,306
Weighted-average outstanding shares — basic (in shares)	48,687	47,489	48,660	47,361
Effect of dilutive securities (in shares)	258	1,267	275	1,344
Weighted-average outstanding shares — diluted (in shares)	48,945	48,756	48,935	48,705
Earnings per share, basic (in dollars per share)	$ 2.06	$ 2.1	$ 3.96	$ 4.42
Earnings per share, diluted (in dollars per share)	$ 2.05	$ 2.04	$ 3.94	$ 4.3