Leases - Operating Lease Balances (Details) - USD ($) $ in Millions	Oct. 24, 2020	Jul. 25, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 953	$ 921
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease liabilities	$ 332	$ 341
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating lease liabilities	$ 695	$ 661
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Total operating lease liabilities	$ 1,027	$ 1,002