Note 8 - Income Taxes - Components of Income Tax Expense (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Current                 $ 8,500 $ 3,836 $ 2,607
Deferred                 257 874 28
Expense of operating loss carryforwards                 637 766 536
Change in valuation allowance                 (12)
Total income tax expense $ 2,600 $ 2,639 $ 2,072 $ 2,083 $ 1,667 $ 1,453 $ 1,264 $ 1,092 $ 9,394 $ 5,476 $ 3,159