Note 2 - Summary of Significant Accounting Policies - Inventory Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory reserves	$ 946
Inventory reserves	2,495	$ 946
SEC Schedule, 12-09, Reserve, Inventory [Member]
Inventory reserves	946	774	$ 483
Charge to costs and expenses	1,592	138	312
Other (deductions) additions	(43)	34	(21)
Inventory reserves	$ 2,495	$ 946	$ 774