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Organization and Significant Accounting Policies - Narrative (Details) - shares |  | 3 Months Ended
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Jul. 01, 2025 | Jun. 30, 2026 | Jun. 30, 2025
Summary Of Significant Accounting Policies [Line Items] |  |  |
Potential diluted common shares outstanding (in shares) |  | 200,000 | 0
AZEK |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
James Hardie Common Shares issued (in shares) | 148,861,787 |  |
Contingent Shares Not Expected To Vest |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Potential diluted common shares outstanding (in shares) |  | 1,600,000 | 800,000

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 260 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482662/260-10-50-1 + Details
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