Accounting for Leases as a Lessee - Leases included in the Consolidated Balance Sheet (Details) $ in Millions	Apr. 30, 2020 USD ($)
Operating Leases
ROU Assets	$ 1,032
Operating lease liabilities - current	197
Operating lease liabilities - non-current	917
Total operating lease liabilities	1,114
Finance Leases
Gross finance lease ROU assets	53
Less: Accumulated depreciation	(2)
Net finance lease ROU assets	51
Finance lease liabilities - current	4
Finance lease liabilities - non-current	55
Total finance lease liabilities	59
Total ROU assets	1,083
Total lease liabilities	$ 1,173