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