Note 7 - Customer and Geographic Information - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues	$ 24,289	$ 25,081
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Revenues	$ 24,289	$ 25,081
Percentage of Revenues	100.00%	100.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | UNITED STATES
Revenues	$ 11,634	$ 12,121
Percentage of Revenues	48.00%	48.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | TAIWAN, PROVINCE OF CHINA
Revenues	$ 3,837	$ 2,184
Percentage of Revenues	16.00%	9.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | GERMANY
Revenues	$ 2,308	$ 3,035
Percentage of Revenues	10.00%	12.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | KOREA, REPUBLIC OF
Revenues	$ 1,990	$ 3,313
Percentage of Revenues	8.00%	13.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member] | Rest of the World [Member]
Revenues	$ 4,520	$ 4,428
Percentage of Revenues	18.00%	18.00%