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Fair Value Measurements Fair Value Measurements (Assets Measured On Recurring Basis Unobservable Input Reconciliation) (Details) - USD ($)
$ in Millions
9 Months Ended
Apr. 26, 2020
Apr. 28, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair Value, Level 3 investments at beginning of year $ 76 $ 77
Fair Value, Level 3 investment gain (Loss) Included in Earnings (46) 1
Fair Value, Level 3 investment Purchases 1 0
Fair Value, Level 3 Investment, Settlements (1) 0
Fair Value, Level 3 investments at end of year $ 30 $ 78