Note 6 - Income Taxes (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Deferred Tax Assets, Valuation Allowance, Total	$ 0
Internal Revenue Service (IRS) [Member]
Open Tax Year	2007
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 3,600
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Subject to Expiration	3,500
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Subject to Expiration	$ 2,800