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Pension Benefit Obligations - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items] |  |  |
Aggregate contributions to multiemployer plans | $ 2.7 | $ 2.5 |
U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected employer contributions in next fiscal year | $ 10.8 |  |
Weighted-average long-term rate of return on assets assumption (as percent) | 6.25% | 6.90% | 7.00%
Aggregate contributions to multiemployer plans | $ 10.6 | $ 11.9 | $ 8.2
Int’l |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected employer contributions in next fiscal year | $ 25.0 |  |
Weighted-average long-term rate of return on assets assumption (as percent) | 5.51% | 5.74% | 6.04%
Aggregate contributions to multiemployer plans | $ 23.7 | $ 25.1 | $ 24.8
Pension Plan, Defined Benefit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Applicable deferred income taxes, included in OCI arising from net prior service cost and net gain/loss | $ 1.1 | $ 2.1 | $ 3.1

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