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Litigation and Related Matters (Narrative) (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | 60 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2010 Site | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) Site | Sep. 30, 2024 USD ($) | Dec. 31, 2007 | Dec. 31, 2021 USD ($) | Dec. 31, 2024 USD ($)
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Settlement agreement amount of litigation agreement |  |  |  |  |  |  | $ 53.0 |
Estimated cost for non-groundwater elements |  |  |  | $ 8.0 |  |  |  |
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration] |  | Liabilities, Noncurrent |  | Liabilities, Noncurrent |  |  |  | Liabilities, Noncurrent
Environmental liabilities |  | $ 4.1 |  | $ 4.1 |  |  |  | $ 4.6
Reserves for potential environmental liabilities |  | 0.1 | $ 0.1 | $ 0.1 | $ 4.1 |  |  |
Cost of Sales [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Reserves for potential environmental liabilities |  |  | 2.5 |  | 2.5 |  |  |
Selling General And Administrative Expenses [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Reserves for potential environmental liabilities |  |  | $ 1.6 |  | $ 1.6 |  |  |
Macon Site [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Number of landfills listed as Superfund site | Site |  |  |  | 2 |  |  |  |
Number of landfills AWI entered into an Administrative Order on Consent for a Removal Action | Site | 1 |  |  |  |  |  |  |
Submission date of final report to EPA | Oct. 31, 2016 |  |  |  |  |  |  |
Elizabeth City [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Percentage of site costs Navy agreed to pay |  |  |  |  |  | 33.33% |  |
Other Long-Term Liabilities [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Environmental liabilities |  | $ 4.1 |  | $ 4.1 |  |  |  | 4.2
Accounts Payable and Accrued Expenses [Member] |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |
Environmental liabilities |  |  |  |  |  |  |  | $ 0.4

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