Note 16 - Income Taxes - Reconciliation Between U.S. Federal Statutory Rate and Effective Rate (Details)		12 Months Ended
	Dec. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statutory federal income tax rate	35.00%	21.00%	35.00%	35.00%
State tax expense, net of federal benefit		5.50%	4.80%	4.50%
Impact of rate change on deferred taxes		0.00%	(4.90%)	0.00%
Permanent items, including nondeductible expenses		(1.40%)	0.10%	0.10%
State investment tax credit		(0.20%)	(0.70%)	(0.10%)
Federal, state and foreign research and development credits		(3.40%)	(1.40%)	(0.90%)
Foreign rate differential		(0.40%)	0.50%	(0.10%)
Domestic production deduction		0.00%	(2.80%)	(2.90%)
Stock compensation		(4.80%)	(0.20%)	0.10%
Non-deductible Section 162(m) compensation limitation		4.30%	0.70%	0.30%
Foreign derived intangible income deduction		(1.30%)	0.00%	0.00%
Effective income tax rate		19.30%	31.10%	36.00%