Leases ROU Assets and Liabilities (Details) $ in Millions	Apr. 30, 2020 USD ($)
Leases [Abstract]
Right-of-use assets	$ 51
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Lease Liabilities:
Current	$ 16
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent
Non-current	$ 37
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Total	$ 53