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, 2022	Mar. 31, 2021
Net income	$ 79,566	$ 45,413
Weighted-average outstanding shares - basic (in shares)	46,424	45,498
Effect of dilutive securities (in shares)	1,826	2,213
Weighted-average outstanding shares - diluted (in shares)	48,250	47,711
Earnings per share, basic (in dollars per share)	$ 1.71	$ 1.00
Earnings per share, diluted (in dollars per share)	$ 1.65	$ 0.95