Debt and Other Financing Activities - Summary of Long-term Debt (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Sep. 30, 2025 |
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| Debt Instrument [Line Items] | ||||||
| Carrying value of debt | $ 1,383 | $ 1,394 | ||||
| Other | [1] | (5) | (6) | |||
| Long-term debt (less debt issuance costs) | [2] | 1,374 | 1,384 | |||
| 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 | 571 | 586 | ||||
| 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 | $ 76 | $ 72 | ||||
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- Definition Other short term and long term debt. No definition available.
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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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