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Investments (Aggregated Balance Sheet Summarized Financial Information for Partnerhips in our Alternative Investment Portfolio) (Details) - Investments Accounted For Under The Equity Method [Member] - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Investments	$ 7,527	$ 10,096
Total assets	8,515	10,695
Total liabilities	316	545
Partners' capital	$ 8,199	$ 10,150

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