Income Taxes - Narrative (Details) $ in Millions	2 Months Ended	12 Months Ended
	Nov. 18, 2025 USD ($)	Sep. 30, 2025 USD ($) component	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Income Tax Contingency [Line Items]
Number of components | component		2
Foreign tax rate differential		$ 29	$ 9	$ 22
Tax rate differential from mix of income and losses in the significant jurisdictions		37	20	33
Tax from nonconsolidated partially owned affiliates		8	11	11
Net operating loss carryforwards		8,200
Net operating loss carryforwards set to expire between 2026 and 2045		5,900
Operating loss carryforwards, valuation allowance		7,000
Operating loss carryforwards, increase		3,700
Operating loss carryforwards, increase, net of tax		873
Unrecognized tax benefits		404	422	527	$ 499
Unrecognized tax benefits that would impact effective tax rate		114
Net accrued interest		21	21	31
Additions for tax positions of prior years		22	18	50
Establishment of uncertain tax positions		10
Settlements with taxing authorities		6	115	11
Benefit from settlements with taxing authorities			63
Unremitted earnings of foreign subsidiaries		33	39
Income taxes paid		92	96	94
Audit settlement tax benefit		25
Change in valuation allowance		828	90	(61)
Deduction, impairment losses		13
Impact of tax rate changes		69	(1)	0
EMEA
Income Tax Contingency [Line Items]
Change in valuation allowance		$ 19
Subsequent Event
Income Tax Contingency [Line Items]
Tax audit settlement	$ 20
Foreign tax authority | China
Income Tax Contingency [Line Items]
Decrease in valuation allowance			14
Foreign tax authority | Mexico
Income Tax Contingency [Line Items]
Decrease in valuation allowance			8
Increase in valuation allowance			5
Deferred tax asset, increase (decrease) of valuation allowance				$ (114)
Foreign tax authority | France
Income Tax Contingency [Line Items]
Decrease in valuation allowance			7
Foreign tax authority | Japan
Income Tax Contingency [Line Items]
Decrease in valuation allowance			6
Foreign tax authority | Poland
Income Tax Contingency [Line Items]
Increase in valuation allowance			14
Foreign tax authority | Luxembourg Inland Revenue
Income Tax Contingency [Line Items]
Increase in valuation allowance			$ 38