Note 9 - Stock-based Compensation - Allocation of Share-based Compensation Expense (Details) - Restricted Stock [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allocation of Share-based Compensation Expense	$ 242	$ 180	$ 638	$ 472
Cost of Sales [Member]
Allocation of Share-based Compensation Expense
Selling and Marketing Expense [Member]
Allocation of Share-based Compensation Expense			4
Research and Development Expense [Member]
Allocation of Share-based Compensation Expense	11	3	26	6
General and Administrative Expense [Member]
Allocation of Share-based Compensation Expense	$ 231	$ 177	$ 608	$ 466