Leases (Lease Liability Maturity) (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Operating Leases
2021	$ 63
2022	154
2023	140
2024	111
2025	85
Thereafter	613
Total future minimum lease payments	1,166
Less: Imputed interest	(273)
Total lease liabilities	893	$ 855
Finance Leases
2021	3
2022	6
2023	7
2024	7
2025	6
Thereafter	34
Total future minimum lease payments	63
Less: Imputed interest	(8)
Total lease liabilities	55	$ 59
Legally binding minimum lease payments for leases signed but not yet commenced	$ 265