Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Unrecognized Tax Benefits		$ 0	$ 0	$ 0
Unrecognized Tax Benefits, Period Increase (Decrease)		0
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		0	0
Unrecognized Tax Benefits, Income Tax Penalties Accrued		$ 0	$ 0	$ 0
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%