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Restructuring Activities - Summary of Amount of Restructuring Severance Expense Related to Program (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2025 | Mar. 31, 2024 | Mar. 31, 2025 | Mar. 31, 2024
Restructuring Cost and Reserve [Line Items] |  |  |  |
Severance expense (income) | $ 8 | $ 18 | $ 10 | $ 21
Utilization (cash paid) | (13) | (1) | (15) | (4)
2025 Restructuring program |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |
Severance expense (income) | 8 | 0 | 12 | 0
Utilization (cash paid) | (5) | 0 | (6) | 0
2023 Restructuring program |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |
Severance expense (income) | 0 | 18 | (2) | 21
Utilization (cash paid) | $ (8) | $ (1) | $ (9) | $ (4)

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