Note 10 - Income Taxes - Reconciliation of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income tax benefit computed at federal statutory tax rate	$ (3,148)	$ (4,348)
Permanent differences	1	6
Write-off of deferred tax asset	2,048
Stock compensation - permanent items		325
State income taxes, net of federal benefit	(930)	(958)
Tax credits	(465)	(1,466)
Change in valuation allowance	2,449	5,409
Foreign rate differential	5	602
Other	40	430
Total