Note 9 - Income Taxes - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Computed “expected” tax rate	(34.00%)	(34.00%)	(34.00%)
Increase (decrease) in income taxes resulting from:
State taxes, net of federal tax benefit	3.70%	2.30%	1.10%
Meals and entertainment	0.20%	0.30%	0.30%
R&D credits	(0.60%)	(0.80%)	(0.70%)
Domestic production deduction	(2.50%)	(2.50%)	(1.40%)
Non-deductible ISO stock option expense	0.30%	0.40%	0.40%
Unrecognized tax benefits	(0.10%)		1.30%
Other	0.30%	1.60%	0.80%
Effective tax rate	35.30%	35.30%	35.80%