Leases - Lease Expenses (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jan. 25, 2020	Jan. 25, 2020
Leases [Abstract]
Operating lease expense	$ 101	$ 214
Short-term lease expense	16	33
Variable lease expense	39	79
Total lease expense	$ 156	$ 326