Note 8 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Revenue	$ 141,363	$ 129,150
CHINA
Revenue	76,198	72,865
TAIWAN, PROVINCE OF CHINA
Revenue	21,347	16,391
Europe [Member]
Revenue	12,984	11,465
KOREA, REPUBLIC OF
Revenue	9,611	9,787
South East Asia [Member]
Revenue	8,672	9,024
JAPAN
Revenue	6,642	5,613
UNITED STATES
Revenue	5,806	3,755
Other Region [Member]
Revenue	$ 103	$ 250

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration