Note 3 - Revenue - Total Revenue by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue	$ 30,548	$ 33,462	$ 51,812	$ 56,848
Percentage of Revenue	100.00%	100.00%	100.00%	100.00%
UNITED STATES
Revenue	$ 24,773	$ 27,447	$ 41,682	$ 46,377
Percentage of Revenue	81.00%	82.00%	81.00%	82.00%
Europe [Member]
Revenue	$ 3,498	$ 4,060	$ 5,889	$ 6,889
Percentage of Revenue	11.00%	12.00%	11.00%	12.00%
Other Location [Member]
Revenue	$ 2,277	$ 1,955	$ 4,241	$ 3,582
Percentage of Revenue	8.00%	6.00%	8.00%	6.00%

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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Data Type:	xbrli:monetaryItemType
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Period Type:	duration