Note 12 - Segment Information - Geographic Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net revenues	$ 229,191	$ 181,381
BRAZIL
Net revenues	$ 54,060	$ 42,853
BRAZIL | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	23.60%	23.60%
SOUTH AFRICA
Net revenues	$ 28,566	$ 26,661
SOUTH AFRICA | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	12.50%	14.70%
MEXICO
Net revenues	$ 21,233	$ 22,128
MEXICO | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	9.30%	12.20%
CHINA
Net revenues	$ 13,181	$ 11,045
CHINA | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	5.80%	6.10%
JAPAN
Net revenues	$ 10,814	$ 8,125
JAPAN | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	4.70%	4.50%
INDIA
Net revenues	$ 9,269	$ 7,308
INDIA | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	4.00%	4.00%
CANADA
Net revenues	$ 8,392	$ 6,913
CANADA | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	3.70%	3.80%
AUSTRALIA
Net revenues	$ 3,405	$ 3,789
AUSTRALIA | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	1.50%	2.10%
TURKEY
Net revenues	$ 222	$ 277
TURKEY | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	0.10%	0.20%
International [Member]
Net revenues	$ 149,142	$ 129,108
International [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Percent of consolidated net revenue	65.20%	71.20%