Note 7 - Inventories (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Inventory, LIFO Reserve, Period Charge	$ 1,300	$ 1,300	$ 2,211	$ 2,924
Inventory Write-down	$ 4,800	$ 3,700	$ 10,800	$ 6,200