Property, Equipment and Technology, Net - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
| Finite-Lived Intangible Assets [Line Items] | |||
| Technology, accumulated amortization | $ 2,300 | $ 1,900 | |
| Depreciation and amortization | 656 | 613 | $ 556 |
| Depreciation and amortization, amortization expense on technology | 60 | 55 | 56 |
| Property, Equipment and Technology | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Depreciation and amortization | 596 | 558 | 500 |
| Technology and Software | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Depreciation and amortization, amortization expense on technology | $ 357 | $ 312 | $ 285 |