Note 8 - Earnings Per Share - Shares Used to Calculate Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Weighted average number of shares used in computation of basic earnings per share: (in shares)	56,003	51,072	55,995	51,051
Additional shares from the assumed exercise of employee stock awards (in shares)	295	210	418	335
Weighted average number of shares used in computation of diluted earnings per share (in shares)	56,298	51,282	56,413	51,386