Fair Value Measurements Fair Value Measurements Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jul. 30, 2017	Jul. 29, 2018	Jul. 30, 2017	Jul. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	$ 12	$ 748	$ 212	$ 141
Cash and Cash Equivalents, at Carrying Value	8	14	8
Long-term Debt	2,499	8,595	2,499
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	8	14	8
Long-term Debt, Fair Value	$ 2,582	$ 8,347	$ 2,582