Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 12,993	$ 16,286
Cash, cash equivalents, restricted cash and restricted cash equivalents	18,948	21,990	$ 19,128	$ 20,377
U.S. litigation escrow
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and restricted cash equivalents:	1,584	1,764
Customer collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and restricted cash equivalents:	3,367	3,005
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and restricted cash equivalents:	$ 1,004	$ 935