Note 6 - Net Income Per Share - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income	$ 124,337	$ 68,770	$ 318,582	$ 169,352
Weighted-average outstanding shares - basic (in shares)	46,829	45,970	46,643	45,754
Effect of dilutive securities (in shares)	1,520	1,882	1,652	2,018
Weighted-average outstanding shares - diluted (in shares)	48,349	47,852	48,295	47,772
Earnings per share, basic (in dollars per share)	$ 2.66	$ 1.50	$ 6.83	$ 3.70
Earnings per share, diluted (in dollars per share)	$ 2.57	$ 1.44	$ 6.60	$ 3.55