Note 6 - Earnings Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Net income	$ 96,007	$ 75,028
Basic weighted-average number of common shares outstanding . (in shares)	72,533,239	75,331,976
Dilutive effect of weighted-average outstanding common share equivalents RSUs (in shares)	366,423	387,399
Diluted weighted-average number of common shares outstanding (in shares)	72,899,662	75,719,375
Average restricted stock units with anti-dilutive effect (in shares)	777	22,574
Basic (in dollars per share)	$ 1.32	$ 1.00
Diluted (in dollars per share)	$ 1.32	$ 0.99