Long-Term Obligations and Commitments - Operating Lease Commitments and Unconditional Purchase Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
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 2018	$ 63
Purchase obligation due 2019	42
Purchase obligation due 2020	24
Purchase obligation due 2021	19
Purchase obligation due 2022	0
Purchase obligation due thereafter	0
Total purchase obligations	148
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating lease commitments due 2018	61
Operating lease commitments due 2019	51
Operating lease commitments due 2020	49
Operating lease commitments due 2021	47
Operating lease commitments due 2022	46
Operating lease commitments due thereafter	130
Total operating lease commitments	384
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Sublease income 2018	24
Sublease income 2019	21
Sublease income 2020	19
Sublease income 2021	16
Sublease income 2022	7
Sublease income thereafter	0
Total sublease income	87
Operating Leases, Rent Expense, Net [Abstract]
Net operating lease commitments 2018	37
Net operating lease commitments 2019	30
Net operating lease commitments 2020	30
Net operating lease commitments 2021	31
Net operating lease commitments 2022	39
Net operating lease commitments due thereafter	130
Total net operating lease commitments	297
Rent expense	34	$ 36	$ 59
Sublease income	$ 22	$ 10	$ 0