Leases - Schedule of Operating Lease Right of Use Assets and Operating Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Leases [Abstract]
Operating lease right-of-use assets	$ 320	$ 335
Operating lease liabilities - current	89	89
Operating lease liabilities - noncurrent	231	246
Present value of lease liabilities	$ 320	$ 335
Weighted average remaining lease term:
Operating leases	6 years	6 years
Weighted average discount rate:
Operating leases	5.10%	5.20%
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other noncurrent assets	Other noncurrent assets
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent