Leases Maturities of Lease Liabilities (Details) $ in Millions	Apr. 30, 2020 USD ($)
Leases [Abstract]
Finance Lease, Liability, Payments, Remainder of Fiscal Year	$ 0
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	17
Finance Lease, Liability, Payments, Due Year Two	1
Lessee, Operating Lease, Liability, Payments, Due Year Two	33
Finance Lease, Liability, Payments, Due Year Three	1
Lessee, Operating Lease, Liability, Payments, Due Year Three	25
Finance Lease, Liability, Payments, Due Year Four	0
Lessee, Operating Lease, Liability, Payments, Due Year Four	20
Finance Lease, Liability, Payments, Due Year Five	0
Lessee, Operating Lease, Liability, Payments, Due Year Five	13
Finance Lease, Liability, Payments, Due after Year Five	0
Lessee, Operating Lease, Liability, Payments, Due after Year Five	32
Finance Lease, Liability, Payments, Due	2
Lessee, Operating Lease, Liability, Payments, Due	140
Finance Lease, Liability, Undiscounted Excess Amount	0
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	16
Finance Lease, Liability	2
Operating Lease, Liability	$ 124