Note 5 - Income Taxes - Components of Income Tax Expense (Benefit) From Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Current income tax expense
Federal	$ 2,436	$ 3,003
State	128	114
Total current income tax expense	2,564	3,117
Deferred income tax (benefit) expense
Federal	467	(26)
State	21	38
Total deferred income tax expense	488	12
Change in valuation allowance		13
Total income tax expense	$ 3,052	$ 3,142