Note 5 - Income Taxes - Reconciliation of Effective Rate with Federal Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal statutory rate	21.00%	34.00%	34.00%
State income taxes, net of federal benefit	0.00%	(0.20%)	0.10%
Permanent differences	0.20%	0.40%	0.10%
Stock based compensation	0.10%	(0.70%)	0.00%
Federal R&D Credits	(1.70%)	(1.30%)	(1.10%)
Foreign Taxes, net of federal benefit	20.50%	7.10%	0.00%
Federal Deferred Rate Decrease	0.00%	(14.20%)	0.00%
Effective tax rate	40.10%	25.10%	33.10%