Other Financial Information - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 15,481	$ 10,111
Less: Accumulated amortization	4,211	3,848
Net carrying amount	11,270	6,263
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Net carrying amount	6,612	3,353
Intellectual Property
Finite-Lived Intangible Assets [Line Items]
Net carrying amount	$ 4,445	$ 2,707