Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Lease extension period (up to)	10 years
Termination period	1 year
Lease liabilities	$ 318		$ 330
Other occupancy expenses	4	$ 4
Access Industries
Lessee, Lease, Description [Line Items]
Lease liabilities	$ 121
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	20 years