Note 3 - Income Tax (Details Textual) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Deferred Tax Assets, Valuation Allowance, Total	$ 0
Effective Income Tax Rate Reconciliation, Percent, Total	25.00%	(184.50%)
Alternative Minimum Tax [Member]
Tax Credit Carryforward, Amount	$ 0
Alternative Minimum Tax Credit [Member]
Tax Credit Carryforward, Amount		$ 0
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	0	0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	$ 43	$ 33