Derivative Instruments and Hedging Activities - Location and Fair Values of Derivative Instruments and Hedging Activities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Derivative [Line Items]
Total assets	$ 34	$ 56
Total liabilities	3,319	3,280
Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total assets	27	43
Total liabilities	3,319	3,275
Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total assets	7	13
Total liabilities	0	5
Other current assets | Foreign currency exchange derivatives | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total assets	18	16
Other current assets | Foreign currency exchange derivatives | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total assets	7	13
Other current assets | Interest rate swaps | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total assets	0	22
Other current assets | Interest rate swaps | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total assets	0	0
Other current assets | Commodity derivatives | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total assets	2	0
Other current assets | Commodity derivatives | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total assets	0	0
Other noncurrent assets | Cross-currency interest rate swap | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total assets	7	5
Other noncurrent assets | Cross-currency interest rate swap | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total assets	0	0
Other current liabilities | Foreign currency exchange derivatives | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	17	20
Other current liabilities | Foreign currency exchange derivatives | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	0	5
Other current liabilities | Commodity derivatives | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	0	2
Other current liabilities | Commodity derivatives | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	0	0
Long-term debt | Foreign currency denominated debt | Derivatives and Hedging Activities  Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	3,302	3,253
Long-term debt | Foreign currency denominated debt | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivative [Line Items]
Total liabilities	$ 0	$ 0