Note 3 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands		3 Months Ended
Mar. 06, 2020	Mar. 31, 2020	Mar. 31, 2019
Fair Value Adjustment of Warrants		$ (137)	$ 57
The July 2011 Warrants [Member]
Class of Warrant or Right, Expired During Period (in shares)	35,107	35,107
Fair Value Adjustment of Warrants		$ (15)
The March 2015 Warrants [Member]
Class of Warrant or Right, Expired During Period (in shares)	7,419	7,419

Amount of expense (income) related to adjustment to fair value of warrant liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 25
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=109262497&loc=d3e20148-110875

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