Fair Value Measurements and Investments - Additional Information (Details) - USD ($) $ in Millions |
12 Months Ended | ||
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Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2023 |
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Unrealized gain (loss) on investments | $ 17 | $ 12 | $ (102) |
| Senior Notes | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Carrying value of debt | 25,200 | 20,800 | |
| Senior Notes | Estimate of Fair Value Measurement | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Estimated fair value of debt | $ 23,300 | $ 19,200 | |
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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/exampleRef
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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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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of unrealized gain (loss) on investment. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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