Other Financial Information (Intangibles) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 5,910	$ 5,911
Less: Accumulated amortization	3,119	3,034
Net carrying amount	2,791	2,877
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Net carrying amount	$ 1,449	$ 1,495

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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