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Financial Information by Segment & Geographic Area - Schedule of Reconciliation of Segment Earnings before Interest and Income Taxes to Income (Loss) before Income Taxes and Equity in Earnings of Affiliated Companies (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
Segment Reporting Information [Line Items] |  |  |
Interest Expense | $ (76) | $ (81) | $ (90)
Less: Equity in earnings of affiliated companies, net of tax | 7 | 6 | 5
Operating Segments [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Segment EBIT | 702 | 701 | 607
Less: Equity in earnings of affiliated companies, net of tax | 7 | 6 | 5
Reconciling Items [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Segment EBIT | 702 | 701 | 607
Interest Expense | (76) | (81) | (90)
Unallocated corporate costs | (52) | (68) | (54)
General unallocated income (expense) | 28 | 42 | 22
Less: Equity in earnings of affiliated companies, net of tax | 7 | 6 | 5
Income (loss) from operations before income taxes and equity in earnings of affiliated companies | 565 | 529 | 451
Certain Items [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Certain items | $ (30) | $ (59) | $ (29)

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