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Debt and Other Financing Activities - Summary of Long-term Debt (Details) - USD ($) $ in Millions		Mar. 31, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Carrying value of debt		$ 1,347	$ 1,361
Other	[1]	43	(8)
Total debt		1,386	1,349
Short-term debt - Note H		50	0
Long-term debt (less debt issuance costs)		1,336	1,349
3.375% Senior Notes, due 2031 [Member]
Debt Instrument [Line Items]
Carrying value of debt		450	450
2.00% Senior Notes Due 2028 [Member]
Debt Instrument [Line Items]
Carrying value of debt		541	558
6.875% Notes due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of debt		282	282
6.50% Junior Subordinated Notes, Due 2029 [Member]
Debt Instrument [Line Items]
Carrying value of debt		$ 70	$ 67
[1] Other includes $11 million and $12 million of debt issuance costs as of March 31, 2025 and September 30, 2024, respectively. The current portion of the long-term debt was zero for both March 31, 2025 and September 30, 2024.

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