Summary of Significant Accounting Policies Depreciation (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 484	$ 463	$ 1,400	$ 1,400

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration