Leases Maturities of Lease Liabilities (Details) $ in Millions	Jan. 31, 2020 USD ($)
Leases [Abstract]
Lessee, Operating Lease, Lease Not yet Commenced, Liability	$ 21
Finance Lease, Liability, Payments, Remainder of Fiscal Year	0
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	26
Finance Lease, Liability, Payments, Due Year Two	1
Lessee, Operating Lease, Liability, Payments, Due Year Two	28
Finance Lease, Liability, Payments, Due Year Three	1
Lessee, Operating Lease, Liability, Payments, Due Year Three	22
Finance Lease, Liability, Payments, Due Year Four	0
Lessee, Operating Lease, Liability, Payments, Due Year Four	17
Finance Lease, Liability, Payments, Due Year Five	0
Lessee, Operating Lease, Liability, Payments, Due Year Five	12
Finance Lease, Liability, Payments, Due after Year Five	0
Lessee, Operating Lease, Liability, Payments, Due after Year Five	19
Finance Lease, Liability, Payments, Due	2
Lessee, Operating Lease, Liability, Payments, Due	124
Finance Lease, Liability, Undiscounted Excess Amount	0
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	15
Finance Lease, Liability	2
Operating Lease, Liability	$ 109