Note 10 - Income Taxes (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent			1.30%	1.20%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent			(0.10%)	0.50%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%	35.00%
Effective Income Tax Rate Reconciliation, Percent	40.40%	40.20%	40.50%	40.70%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent			4.30%	4.40%
Effective Income Tax Rate Reconciliation, Tax Contingency, State and Local, Percent				0.40%