Note 4 - Revenue and Segment Information - Capital Expenditures (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Capital expenditures	$ 102	$ 102
Corporate, Non-Segment [Member]
Capital expenditures	0	0
Refinery Operations [Member] \| Operating Segments [Member]
Capital expenditures	102	102
Tolling and Terminaling [Member] \| Operating Segments [Member]
Capital expenditures	$ 0	$ 0

Amount of expenditure for addition to long-lived assets included in determination of segment assets by chief operating decision maker (CODM) or otherwise regularly provided to CODM. Excludes expenditure for addition to financial instrument, long-term customer relationship of financial institution, mortgage and other servicing rights, deferred policy acquisition cost, and deferred tax assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 25
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-25

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482785/280-10-55-48

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