Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Lease extension period (up to)	10 years		10 years
Termination period			1 year
Lease liabilities	$ 294		$ 294		$ 330
Other occupancy expenses	5	$ 3	17	$ 11
Additional operating leases not yet commenced	28		28
Access Industries
Lessee, Lease, Description [Line Items]
Lease liabilities	$ 113		$ 113
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year		1 year
Leases not yet commenced, term	10 years		10 years
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	20 years		20 years
Leases not yet commenced, term	16 years		16 years