Note 8 - Segments - Sales by Geographic Region (Details) - Revenue, Segment Benchmark [Member] - Geographic Concentration Risk [Member]	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
UNITED STATES
Percentage of sales	63.00%	60.00%
Europe [Member]
Percentage of sales	13.00%	20.00%
Other [Member]
Percentage of sales	24.00%	20.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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