Note 16 - Segment Information - Summary of Operations Within Geographic Areas Based on Customer Locations (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 117,438	$ 124,753	$ 137,869
HONG KONG
Revenues	36,666	46,119	56,768
JAPAN
Revenues	14,284	16,567	18,440
Europe [Member]
Revenues	9,022	9,882	9,703
UNITED STATES
Revenues	5,876	4,927	4,696
CHINA
Revenues	16,107	16,096	10,244
TAIWAN, PROVINCE OF CHINA
Revenues	23,940	22,442	16,428
KOREA, REPUBLIC OF
Revenues	7,341	4,190	17,503
Other Geographic Regions [Member]
Revenues	$ 4,202	$ 4,530	$ 4,087

Amount, including 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

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