Note 7 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Revenue	$ 159,975	$ 128,939	[1]	$ 428,885	$ 341,499	[1]
CHINA
Revenue	91,509	66,645		245,580	185,054
TAIWAN, PROVINCE OF CHINA
Revenue	20,774	27,387		55,315	59,548
Europe [Member]
Revenue	12,579	10,726		36,696	28,227
KOREA, REPUBLIC OF
Revenue	11,406	9,279		30,046	25,594
South East Asia [Member]
Revenue	11,259	7,179		28,261	20,476
JAPAN
Revenue	6,895	4,813		18,994	14,584
UNITED STATES
Revenue	5,375	2,781		13,404	7,711
Other Region [Member]
Revenue	$ 178	$ 129		$ 589	$ 305

[1] 2017 amounts have not been adjusted under the modified retrospective method.