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Other Income (Expense), Net (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2021 | Mar. 31, 2020
Other Income (Expense), Net |  |  |  |
External services | $ 3 | $ 3 | $ 7 | $ 6
Interest income | 3 | 5 | 6 | 10
Gains (losses) on investments | 2 | (11) | 11 | (6)
Miscellaneous | 3 | 2 | 2 | 1
Total other income (expense), net | $ 11 | $ (1) | $ 26 | $ 11

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