Employee Benefit Plans - Summary of Restricted Stock and Stock Unit Activity (Details) - Restricted Stock/Stock Units - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jan. 23, 2021	Jul. 25, 2020
Restricted Stock/ Stock Units
Beginning balance (in shares)	96	100
Granted and assumed (in shares)	33	49
Vested (in shares)	(21)	(44)
Canceled/forfeited/other (in shares)	(9)	(9)
Ending balance (in shares)	99	96
Weighted-Average Grant Date Fair Value per Share
Beginning balance (in dollars per share)	$ 42.03	$ 38.66
Granted and assumed (in dollars per share)	37.90	42.61
Vested (in dollars per share)	39.05	35.20
Canceled/forfeited/other (in dollars per share)	41.63	40.45
Ending balance (in dollars per share)	$ 41.35	$ 42.03
Aggregate Fair  Value
Vested	$ 908	$ 2,045