Leases - Assets and Liabilities Lessee (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
ROU assets:
Operating lease ROU assets	$ 368	$ 390
Finance lease ROU assets	48	49
Total ROU assets	$ 416	$ 439
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	$ 82	$ 81
Operating lease liabilities — noncurrent	294	318
Finance lease liabilities — current	4	4
Finance lease liabilities — noncurrent	41	41
Total lease liabilities	$ 421	$ 444
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