Note 7 - Inventories (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Write-down	$ 4,419	$ 695	$ 654
Nonsaleable Inventory [Member]
Inventory Write-down	800
HA Raw Materials [Member]
Inventory Write-down	1,300
HYAFF-based Products [Member]
Inventory Write-down	$ 1,200