Note 4 - Balance Sheet Components - Intangible assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Intangible assets, gross	$ 20,380	$ 20,380
Less: accumulated amortization	(5,452)	(5,019)
Intangible assets, net	14,928	15,361
Purchased Technology [Member]
Intangible assets, gross	20,300	20,300
Intellectual Property [Member]
Intangible assets, gross	$ 80	$ 80