Leases Schedule of Lease Liability Maturity (Details) $ in Millions |
Apr. 30, 2019
USD ($)
|
|---|---|
| Operating Lease Liabilities, Payments Due [Abstract] | |
| Remainder of 2020 | $ 1,819 |
| 2021 | 2,346 |
| 2022 | 2,105 |
| 2023 | 1,903 |
| 2024 | 1,718 |
| Thereafter | 15,699 |
| Total undiscounted lease obligations | 25,590 |
| Less imputed interest | (8,123) |
| Net lease obligations | 17,467 |
| Finance Lease Liabilities, Payments, Due [Abstract] | |
| Remainder of 2020 | 533 |
| 2021 | 676 |
| 2022 | 621 |
| 2023 | 506 |
| 2024 | 447 |
| Thereafter | 5,367 |
| Total undiscounted lease obligations | 8,150 |
| Less imputed interest | (3,905) |
| Net lease obligations | $ 4,245 |