Note 9 - Significant Customers, Concentration of Credit Risk, and Geographic Information - Geographic Activity, Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net revenues	$ 3,703	$ 3,154	$ 9,998	$ 9,320
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Net revenues	$ 3,703	$ 3,154	$ 9,998	$ 9,320
Percentage of net revenues	100.00%	100.00%	100.00%	100.00%
North America [Member] | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Net revenues	$ 2,267	$ 1,723	$ 6,184	$ 5,082
Percentage of net revenues	61.20%	54.60%	61.90%	54.50%
Europe [Member] | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Net revenues	$ 418	$ 545	$ 1,195	$ 1,427
Percentage of net revenues	11.30%	17.30%	11.90%	15.30%
Asia Pacific [Member] | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Net revenues	$ 1,016	$ 883	$ 2,576	$ 2,769
Percentage of net revenues	27.40%	28.00%	25.80%	29.70%
Other Geographic Areas [Member] | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Net revenues	$ 2	$ 3	$ 43	$ 42
Percentage of net revenues	0.10%	0.10%	0.40%	0.50%