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Note 8 - Commitments and Contingencies (Details Textual) $ in Millions	1 Months Ended
	Jan. 31, 2017 USD ($)	Sep. 30, 2025 USD ($)	Nov. 30, 2024	Jun. 30, 2014 USD ($)
Letters of Credit Outstanding, Amount		$ 1.6
Capital Addition Purchase Commitments [Member]
Other Commitment		$ 2.1
Portland Harbor Natural Resources Trustee Council [Member]
Loss Contingency, Accrual, Current				$ 0.4
Portland Harbor Superfund Site [Member]
Number Of Potentially Responsible Parties	150		60
Estimated Cost of EPA Selected Remedy	$ 1,000.0
Estimated Time to Complete Selected EPA Remedy (Year)	13 years
Lower Willamette Group [Member]
Number Of Potentially Responsible Parties	14

X

- Definition

The estimated cost of the remedy selected by EPA.

+ References

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X

- Definition

The estimated amount of time to complete the selected EPA remedy.

+ References

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X

- Definition

Number of potentially responsible parties for Portland Harbor Superfund site.

+ References

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X

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
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- Definition

Amount of loss contingency liability expected to be resolved within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 235
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-Paragraph 2
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