Note 2 - Summary of Significant Accounting Policies - Warrant Accrual Activity (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Beginning balance	$ 50	$ 80
Add: Accruals for warranties issued during the period	0	17
Less: Adjustment for inventory at cost and excessive and obsolete inventory	0	0
Ending balance	$ 50	$ 97

Amount as of the balance sheet date of the aggregate standard product warranty liability that is expected to be paid within one year or the normal operating cycle, if longer. Does not include the balance for the extended product warranty liability.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482425/460-10-50-8

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (c)(5)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482425/460-10-50-8

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