Fair Value Measurements and Investments - Schedule of Non-Marketable Equity Securities (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2023 |
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| Fair Value Disclosures [Abstract] | |||
| Initial cost basis | $ 711 | $ 711 | |
| Upward adjustments | 564 | 910 | |
| Downward adjustments, including impairment | (219) | (465) | |
| Carrying amount | 1,056 | 1,156 | |
| Upward adjustments | 14 | 10 | $ 94 |
| Downward adjustments, including impairment | $ (51) | $ (35) | $ (99) |
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- Definition Amount of investment in equity security without readily determinable fair value. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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- Definition Equity Securities Without Readily Determinable Fair Value, Cost No definition available.
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- Definition Equity Securities Without Readily Determinable Fair Value, Impairment And Downward Price Adjustment, Annual Amount No definition available.
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- Definition Equity Securities Without Readily Determinable Fair Value Impairment And Downward Price Adjustment, Cumulative Amount No definition available.
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