Leases - Supplemental Information (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 24, 2020	Oct. 26, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities — operating cash flows	$ 105	$ 104
Right-of-use assets obtained in exchange for operating leases liabilities	$ 115	$ 48