Note 9 - Geographic Information and Major Customer Data - Revenues Based on Customer Location (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018	Sep. 30, 2019		Sep. 30, 2018
Revenues	$ 23,471		$ 21,413	$ 58,840		$ 56,476
UNITED STATES
Revenues	3,811		2,259	7,713		6,087
Europe and Middle East [Member]
Revenues	6,911		6,139	13,245		11,305
Asia Pacific [Member]
Revenues	12,749		13,015	37,882		39,084
GERMANY
Revenues	5,425		5,600	10,613		8,582	[1]
CHINA
Revenues	8,993		$ 10,192	25,542		23,127
KOREA, REPUBLIC OF
Revenues		[1]			[1]	7,152
JAPAN
Revenues				$ 6,544		$ 6,116

[1] Less than 10%