Property, Equipment and Technology, Net - Schedule of Property, Equipment and Technology, Net (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	$ 10,106	$ 9,297
Accumulated depreciation and amortization	(5,870)	(5,473)
Property, equipment and technology, net	4,236	3,824
Land
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	72	72
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	1,004	1,042
Furniture, equipment and leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	2,240	2,301
Technology
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	6,599	5,660
Assets not yet placed in service
Property, Plant and Equipment [Line Items]
Total property, equipment and technology	$ 191	$ 222