Leases - Assets and Liabilities Lessee (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
ROU assets:
Operating lease ROU assets	$ 420	$ 368
Finance lease ROU assets	50	48
Total ROU assets	$ 470	$ 416
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	$ 87	$ 82
Operating lease liabilities — noncurrent	340	294
Finance lease liabilities — current	5	4
Finance lease liabilities — noncurrent	45	41
Total lease liabilities	$ 477	$ 421
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 and Lease Obligation	Long-Term Debt and Lease Obligation