Leases - Assets and Liabilities Lessee (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
ROU assets:
Operating lease ROU assets	$ 417	$ 420
Finance lease ROU assets	54	50
Total ROU assets	$ 471	$ 470
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Lease liabilities:
Operating lease liabilities — current	$ 86	$ 87
Operating lease liabilities — noncurrent	343	340
Finance lease liabilities — current	3	5
Finance lease liabilities — noncurrent	52	45
Total lease liabilities	$ 484	$ 477
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current	Other Liabilities, Current
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other noncurrent liabilities	Other noncurrent liabilities
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current maturities of long-term debt	Current maturities of long-term debt
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt	Long-term debt