Note 2 - Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
Dec. 31, 2017
Computer Equipment and Software [Member]
Estimated useful lives (Year)	3 years
Laboratory and Manufacturing Equipment [Member]
Estimated useful lives (Year)	3 years
Furniture and Fixtures [Member]
Estimated useful lives (Year)	3 years
Leasehold Improvements [Member]
Estimated useful lives	5 years or lease term, if shorter

Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 35
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68071081&loc=d3e1205-110223

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration