Note 11 - Financial Instruments - Changes in Fair Value of Level 3 Measurements (Details) $ in Thousands	6 Months Ended
Jun. 30, 2019 USD ($)
Closing balance	$ 1,915
Change in fair value of warrants, included in the condensed consolidated statements of comprehensive loss	1,634
Closing balance – June 30, 2019	$ 281

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant