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Segment Information and Major Customers (Property and Equipment Information for Geographic Areas) (Details) - USD ($)
$ in Millions
Jan. 27, 2018
Jul. 29, 2017
Segment Reporting, Asset Reconciling Item [Line Items]    
Property and equipment, net $ 3,113 $ 3,322
United States    
Segment Reporting, Asset Reconciling Item [Line Items]    
Property and equipment, net 2,555 2,711
International    
Segment Reporting, Asset Reconciling Item [Line Items]    
Property and equipment, net $ 558 $ 611