Note 13 - 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	39.00%	39.40%	38.90%	39.10%
Effective Income Tax Rate Reconciliation, Tax Contingency, Amount	$ 146,200	$ 190,000	$ 321,000	$ 365,000
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount	84,000	143,000	133,400	229,000
Effective Income Tax Rate Reconciliation, Exercise of Stock Options, Amount	123,000		244,000
Income Tax Expense (Benefit)	$ 6,758,000	$ 7,700,000	$ 14,757,000	$ 16,398,000
Earliest Tax Year [Member]
Open Tax Year			2013