Long-Term Obligations and Commitments - Operating Lease Commitments and Unconditional Purchase Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligation due 2020	$ 302
Purchase obligation due 2021	65
Purchase obligation due 2022	9
Purchase obligation due 2023	0
Purchase obligation due 2024	0
Purchase obligation due thereafter	0
Total purchase obligations	376
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating lease commitments due 2020	68
Operating lease commitments due 2021	61
Operating lease commitments due 2022	55
Operating lease commitments due 2023	51
Operating lease commitments due 2024	50
Operating lease commitments due thereafter	67
Total operating lease commitments	352
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Sublease income 2020	23
Sublease income 2021	21
Sublease income 2022	10
Sublease income 2023	1
Sublease income 2024	1
Sublease income thereafter	1
Total sublease income	57
Contractual Obligation, Fiscal Year Maturity [Abstract]
Net operating lease commitments 2020	45
Net operating lease commitments 2019	40
Net operating lease commitments 2022	45
Net operating lease commitments 2023	50
Net operating lease commitments 2024	49
Net operating lease commitments due thereafter	66
Total net operating lease commitments	295
Rent expense	42	$ 38	$ 34
Sublease income	$ 24	$ 23	$ 22