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Investments (Aggregated Balance Sheet Summarized Financial Information for Partnerships in our Alternative Investment Portfolio) (Details) - USD ($) $ in Millions | Sep. 30, 2020 | Sep. 30, 2019
--- | --- | ---
Equity Method Investment, Nonconsolidated Investee or Group of Investees |  |
Assets | $ 58,819 | $ 45,432
Equity Method Investment, Nonconsolidated Investee, Other |  |
Partner's capital | 52,075 | 39,762
Investments Accounted For Under The Equity Method [Member] |  |
Investments | 55,145 | 43,857
Liabilities | $ 6,744 | $ 5,670

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