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Investments (Aggregated Balance Sheet Summarized Financial Information for Partnerships in our Alternative Investment Portfolio) (Details) - Investments Accounted For Under The Equity Method [Member] - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Investments	$ 43,857	$ 28,292
Total assets	45,432	30,377
Total liabilities	5,670	4,532
Partners' capital	$ 39,762	$ 25,845

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