Note 9 - Commitments and Contingencies - Supplemental Lease Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Right-of-use asset, net and lease liabilities (in thousands)	$ 3,506		$ 3,506		$ 2,889
Weighted average remaining lease term (years) (Year)	3 years 1 month 6 days		3 years 1 month 6 days		3 years 6 months
Weighted average discount rate	4.30%		4.30%		3.80%
Lease expense	$ 311	$ 300	$ 886	$ 754
Cost of Sales [Member]
Lease expense	225	218	667	508
General and Administrative Expense [Member]
Lease expense	76	52	188	157
Research and Development Expense [Member]
Lease expense	$ 10	$ 30	$ 31	$ 89