Note 11 - Net Income Per Share - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income	$ 242,023	$ 164,375	$ 108,839
Weighted-average outstanding shares - basic (in shares)	45,851	44,840	43,165
Effect of dilutive securities (in shares)	2,038	2,174	2,598
Weighted-average outstanding shares - diluted (in shares)	47,889	47,014	45,763
Earnings per share, basic (in dollars per share)	$ 5.28	$ 3.67	$ 2.52
Earnings per share, diluted (in dollars per share)	$ 5.05	$ 3.50	$ 2.38