Note 4 - Balance Sheet Components - Intangible assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Intangible assets, gross	$ 22,180	$ 22,180
Less: accumulated amortization	(4,221)	(2,767)
Intangible assets, net	17,959	19,413
Purchased Technology [Member]
Intangible assets, gross	22,100	22,100
Intellectual Property [Member]
Intangible assets, gross	$ 80	$ 80