Note 4 - Balance Sheet Components - Right-of-Use Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Right-of-use assets, net	$ 2,301
Facilities [Member]
Right-of-use assets, net	2,294
Office Equipment [Member]
Right-of-use assets, net	$ 7