Note 8 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 151,007	$ 139,761	$ 292,370	$ 268,911
CHINA
Revenue	94,837	81,207	171,035	154,072
TAIWAN, PROVINCE OF CHINA
Revenue	16,018	18,150	37,365	34,541
Europe [Member]
Revenue	13,040	12,651	26,024	24,116
KOREA, REPUBLIC OF
Revenue	9,623	8,853	19,234	18,640
South East Asia [Member]
Revenue	7,122	7,977	15,794	17,002
JAPAN
Revenue	6,292	6,486	12,934	12,100
UNITED STATES
Revenue	4,013	4,274	9,819	8,029
Other Region [Member]
Revenue	$ 62	$ 163	$ 165	$ 411