Leases - Future Minimum Lease Payments Under Non-cancelable Operating and Finance Leases (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Operating leases
2022	$ 16
2023	14
2024	11
2025	10
2026	9
2027 and thereafter	57
Total lease payments	117
Less: imputed interest	19
Total	$ 98
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Accounts payable and accrued liabilities
Finance leases
2022	$ 5
2023	5
2024	5
2025	4
2026	4
2027 and thereafter	18
Total lease payments	41
Less: imputed interest	8
Total	$ 33	$ 31