Note 10 - Net Income Per Share - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Net income	$ 29,105	$ 25,410
Basic weighted average shares (in shares)	37,068	38,992
Stock options (in shares)	489	770
Restricted stock units (in shares)	110	236
Employee stock purchase plan (in shares)	2	3
Diluted weighted average shares (in shares)	37,669	40,001
Basic (in dollars per share)	$ 0.79	$ 0.65
Diluted (in dollars per share)	$ 0.77	$ 0.64