Note 11 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%		35.00%
Income Tax Expense (Benefit), Total	$ 4,109	$ 1,018	$ 12,501	$ 5,738
Effective Income Tax Rate Reconciliation, Percent, Total	26.20%	30.90%	26.30%	28.00%
Restatement Adjustment [Member]
Income Tax Expense (Benefit), Total					$ (1,900)