Note 13 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit), Total	$ (1,051)	$ 2,571
Effective Income Tax Rate Reconciliation, Percent, Total	13.60%	(31.90%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				35.00%
Deferred Tax Assets, Valuation Allowance, Total	$ 0			$ 0
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%