Note 9 - Stockholders' Equity - Changes in Accumulated Other Comprehensive Loss (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Balance	$ 67,697
Balance	63,432
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(325)
Other comprehensive income (loss)	(86)
Balance	(411)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	(11)
Other comprehensive income (loss)	9
Balance	(2)
AOCI Attributable to Parent [Member]
Balance	(336)
Other comprehensive income (loss)	(77)
Balance	$ (413)