Other Financial Information (Intangibles) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 4,716	$ 4,667
Less: Accumulated amortization	2,002	1,916
Net carrying amount	2,714	2,751
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Net carrying amount	$ 1,476	$ 1,517

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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-Section 50
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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 340
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