Note 11 - Revenue (Details) T in Millions, $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2023 USD ($) T	Dec. 31, 2022 USD ($)	Dec. 31, 2023 T $ / T
REVENUES
Contract term	1 year		1 year
Downward adjustment to revenue \| $	$ 1.3	$ 2.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
REVENUES
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year		1 year
Percentage expected to be satisfied	88.00%		88.00%
Contracts with Indexed Based Pricing Mechanisms
REVENUES
Outstanding performance obligation, mass	2.1		2.1
Fixed Priced Contracts
REVENUES
Outstanding performance obligation, mass	1.4		1.4
Average per ton \| $ / T			166

Refers to the average fixed sales price per ton.

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- Definition

Mass of product allocated to performance obligation.

+ References

No definition available.

+ Details

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- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12A

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- Definition

Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479773/842-30-50-3

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-SubTopic 10
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

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- Definition

Percentage of remaining performance obligation to total remaining performance obligation not recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-SubTopic 10
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

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