Long-Term Obligations and Commitments - Operating Lease Commitments and Unconditional Purchase Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Long Term Obligations and Commitments (Textuals) [Abstract]
Number of additional years lease term can be extended	10 years
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due 2019	$ 175
Purchase obligation due 2020	121
Purchase obligation due 2021	125
Purchase obligation due 2022	73
Purchase obligation due 2023	0
Purchase obligation due thereafter	0
Total purchase obligations	494
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating lease commitments due 2019	66
Operating lease commitments due 2020	61
Operating lease commitments due 2021	59
Operating lease commitments due 2022	51
Operating lease commitments due 2023	49
Operating lease commitments due thereafter	113
Total operating lease commitments	399
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Sublease income 2019	24
Sublease income 2020	22
Sublease income 2021	19
Sublease income 2022	8
Sublease income 2023	0
Sublease income thereafter	0
Total sublease income	73
Operating Leases, Rent Expense, Net [Abstract]
Net operating lease commitments 2019	42
Net operating lease commitments 2020	39
Net operating lease commitments 2021	40
Net operating lease commitments 2022	43
Net operating lease commitments 2023	49
Net operating lease commitments due thereafter	113
Total net operating lease commitments	326
Rent expense	38	$ 34	$ 36
Sublease income	$ 23	$ 22	$ 10