Note 8 - Earnings Per Share - Shares Used to Calculate Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Weighted average number of shares used in computation of basic earnings per share: (in shares)	55,992	51,043	55,990	51,040
Additional shares from the assumed exercise of employee stock awards (in shares)	324	319	512	408
Weighted average number of shares used in computation of diluted earnings per share (in shares)	56,316	51,362	56,502	51,448