Note 16 - Income Taxes - Reconciliation of Federal Statutory Income Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal tax statutory rate	21.00%	21.00%	35.00%
State tax (net of federal benefit)	2.10%	2.00%	1.70%
Share based compensation	(0.50%)	(2.80%)	(0.80%)
Valuation allowance against deferred tax assets	1.40%	0.70%	2.90%
Research and development credit	(2.80%)	(2.50%)	(2.20%)
Foreign rate differential	(0.30%)	(0.10%)	(1.90%)
Tax reserves	1.10%	(0.10%)	0.90%
Domestic manufacturing deduction	0.00%	0.00%	(2.50%)
Miscellaneous	(0.40%)	(0.50%)	(0.20%)
Transition tax	0.00%	(0.80%)	3.20%
Revaluation of deferred tax liability	0.00%	(0.50%)	(5.70%)
Total	21.60%	16.40%	30.40%