Note 11 - Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Taxes at statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	3.90%	3.90%	4.20%
Foreign tax rate differential	(0.10%)	(0.30%)	(0.60%)
Other permanent differences	0.80%	1.90%	2.00%
Prior year tax adjustments	(1.00%)	(1.90%)	(2.30%)
Unrecognized tax benefits	1.00%
Valuation Allowance Release	(0.30%)
Equity-based Compensation	(1.00%)
Tax credits	(0.80%)	(0.50%)	(0.70%)
Taxes at effective rate	37.50%	38.10%	37.60%