Note 1 - Business and Significant Accounting Policies - Shares Used to Calculate Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Weighted average number of shares used in computation of basic earnings per share (in shares)	56,004	51,567	50,867
Additional shares from the assumed exercise of employee stock options (in shares)	398	370	360
Diluted (in shares)	56,402	51,937	51,227