Note 5 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Net Deferred Tax Assets (Liabilities)	$ 7,500		$ 7,500		$ 10,700
Deferred Tax Assets, Operating Loss Carryforwards, Total	5,200		5,200
Operating Loss Carryforwards, Total	30,000		30,000
Deferred Tax Assets, Valuation Allowance, Total	$ 0		$ 0		$ 0