Note 2 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective Income Tax Rate Reconciliation, Percent	32.10%	35.20%	33.50%	33.10%
Increase (Decrease) in Income Tax Expense from Exercise of Options and Dividends Paid to Non-vested Shareholders	$ (323,000)
Increase (Decrease) in Income Tax Expense from Change in State Tax Incentives			$ 38,000
Increase (Decrease) in Income Tax Expense from Adjustments Related to Federal Tax Examinations				$ (48,000)