Note 9 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Liabilities, Intangible Assets	$ 2,217
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	400	$ (400)
Operating Loss Carryforwards, Total	44,700
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	34,900
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	9,800
SAVSU [Member]
Deferred Tax Liabilities, Intangible Assets	1,500
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ (1,500)