Note 12 - Taxes on Income - Activity in the Valuation Allowance (Details) - SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 34,247	$ 28,451	$ 29,782
Additions	14,677	8,789	1,879
Reversals	(6,571)	(6,776)	(2,102)
Other adjustments	1,071	3,783	(1,108)
Balance	$ 43,424	$ 34,247	$ 28,451