Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Tax Contingency [Line Items]
Return to provision adjustments	$ 15	$ (4)	$ 4
Tax benefit related to federal research and development credits	3	8	0
Uncertain tax positions	(3)	7	(3)
Reinvested earnings at foreign subsidiaries	456
Accrued interest and penalties	1	2
Uncertain income tax position not recognized	11	14
Decrease in uncertain tax positions resulting from ongoing audits and settlements	2	0	0
France Tax Authority
Income Tax Contingency [Line Items]
Net operating loss carryforward	11
Spain Tax Authority
Income Tax Contingency [Line Items]
Net operating loss carryforward	5
His Majesty's Revenue and Customs (HMRC)
Income Tax Contingency [Line Items]
Net operating loss carryforward	5
Foreign Tax Jurisdiction
Income Tax Contingency [Line Items]
Tax benefit related to federal research and development credits		$ 8
Release of valuation allowance			$ 8
Domestic Tax Jurisdiction
Income Tax Contingency [Line Items]
Net operating loss carryforward	0
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Net operating loss carryforward	$ 21