Note 13 - Selected Statements of Income Data - Financial Income, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest income	$ 1,873	$ 3,291	$ 4,220
Gain (loss) on available-for-sale marketable securities, net	13	(6)	(28)
Amortization of premium on available-for-sale marketable securities, net	(420)	(444)	(554)
Foreign exchange gain (loss), net	(1,269)	443	(347)
Total	$ 197	$ 3,284	$ 3,291