Leases ROU Assets and Liabilities (Details) $ in Millions	Jul. 31, 2019 USD ($)
Leases [Abstract]
Right-of-use assets	$ 50
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Lease Liabilities:
Current	$ 17
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent
Non-current	$ 33
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Total	$ 50