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Fair Value Measurements Fair Value Measurements (Assets Measured On Recurring Basis Unobservable Input Reconciliation) (Details) - Equity Securities [Member] - USD ($)
$ in Millions
12 Months Ended
Jul. 29, 2018
Jul. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair Value, Level 3 investments at beginning of year $ 49 $ 25
Fair Value, Level 3 investment gain (Loss) Included in Earnings 9 2
Fair Value, Level 3 investment Purchases 19 22
Fair Value, Level 3 investments at end of year $ 77 $ 49