Leases, SoCF (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Lessee, Lease, Description [Line Items]
Operating cash flows for operating leases	$ 72	$ 78	$ 77
Operating cash flows for finance leases	46	37	43
Financing cash flows for finance leases	82	76	56
Lease assets obtained in exchange for lease obligations - finance	28	230	3
Lease assets obtained in exchange for lease obligations - operating	$ 14	$ 115	$ 84