Financial Instruments - Schedule Of Derivative Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Derivative [Line Items]
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Goods and Services Sold	Cost of Goods and Services Sold	Cost of Goods and Services Sold
Gain (Loss) reclassified to earnings	$ (69)	$ 89	$ 97
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other deductions, net	Other deductions, net	Other deductions, net
Derivative Gain Loss Statement Of Income Or Comprehensive Income, Extensible Enumeration Not Disclosed, Flag	Total	Total	Total
Gain (Loss) to other comprehensive income, Total	$ (80)	$ 290	$ 87
Cash Flow Hedging | Commodity
Derivative [Line Items]
Gain (Loss) reclassified to earnings	(19)	12	33
Cash Flow Hedging | Commodity | Cost of sales | Other Comprehensive Income (Loss)
Derivative [Line Items]
Gain (Loss) to other comprehensive income	6	(20)	29
Cash Flow Hedging | Foreign currency
Derivative [Line Items]
Gain (Loss) reclassified to earnings	(128)	48	53
Cash Flow Hedging | Foreign currency | Cost of sales
Derivative [Line Items]
Gain (Loss) reclassified to earnings	65	31	8
Cash Flow Hedging | Foreign currency | Cost of sales | Other Comprehensive Income (Loss)
Derivative [Line Items]
Gain (Loss) to other comprehensive income	42	53	34
Cash Flow Hedging | Foreign currency | Sales
Derivative [Line Items]
Gain (Loss) reclassified to earnings	(3)	(2)	3
Cash Flow Hedging | Foreign currency | Sales | Other Comprehensive Income (Loss)
Derivative [Line Items]
Gain (Loss) to other comprehensive income	0	(9)	3
Net Investment Hedging | Foreign currency | Other Comprehensive Income (Loss)
Derivative [Line Items]
Gain (Loss) to other comprehensive income	$ (128)	$ 266	$ 21