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Investments (Aggregated Balance Sheet Summarized Financial Information for Partnerhips in our Alternative Investment Portfolio) (Details) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Investments [Abstract]
Investments	$ 12,214	$ 13,553
Total assets	12,912	14,253
Total liabilities	657	1,105
Partners' Capital	$ 12,255	$ 13,148

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