Leases Maturities of Lease Liabilities (Details) $ in Millions	Jul. 31, 2020 USD ($)
Leases [Abstract]
Finance Lease, Liability, to be Paid, Remainder of Fiscal Year	$ 0
Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year	8
Finance Lease, Liability, to be Paid, Year Two	1
Lessee, Operating Lease, Liability, to be Paid, Year Two	35
Finance Lease, Liability, to be Paid, Year Three	1
Lessee, Operating Lease, Liability, to be Paid, Year Three	27
Finance Lease, Liability, to be Paid, Year Four	0
Lessee, Operating Lease, Liability, to be Paid, Year Four	21
Finance Lease, Liability, to be Paid, Year Five	0
Lessee, Operating Lease, Liability, to be Paid, Year Five	14
Finance Lease, Liability, to be Paid, after Year Five	0
Lessee, Operating Lease, Liability, to be Paid, after Year Five	33
Finance Lease, Liability, Payment, Due	2
Lessee, Operating Lease, Liability, to be Paid	138
Finance Lease, Liability, Undiscounted Excess Amount	0
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	16
Finance Lease, Liability	2
Operating Lease, Liability	$ 122