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		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net income	$ 114,679	$ 55,169	$ 194,245	$ 100,582
Weighted-average outstanding shares - basic (in shares)	46,675	45,796	46,550	45,647
Effect of dilutive securities (in shares)	1,611	1,958	1,718	2,085
Weighted-average outstanding shares - diluted (in shares)	48,286	47,754	48,268	47,732
Earnings per share, basic (in dollars per share)	$ 2.46	$ 1.20	$ 4.17	$ 2.20
Earnings per share, diluted (in dollars per share)	$ 2.37	$ 1.16	$ 4.02	$ 2.11