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
	Mar. 31, 2023	Mar. 31, 2022
Net income	$ 109,802	$ 79,566
Weighted-average outstanding shares - basic (in shares)	47,234	46,424
Effect of dilutive securities (in shares)	1,421	1,826
Weighted-average outstanding shares - diluted (in shares)	48,655	48,250
Earnings per share, basic (in dollars per share)	$ 2.32	$ 1.71
Earnings per share, diluted (in dollars per share)	$ 2.26	$ 1.65