Comprehensive Income (Loss) (Reclassification Out of Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 28, 2018	Apr. 29, 2017	Apr. 28, 2018	Apr. 29, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total amounts reclassified out of AOCI	$ 45	$ (105)	$ 162	$ (158)
Cumulative translation adjustment and actuarial gains and losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cumulative translation adjustment and actuarial gains and losses	0	(2)	(5)	(1)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized gains and losses on available-for-sale investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income (loss), net	17	(76)	108	(91)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized gains and losses on cash flow hedging instruments | Cash Flow Hedging
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Operating expenses	21	(20)	45	(50)
Cost of sales—service	7	(7)	14	(16)
Net unrealized gains and losses on cash flow hedging instruments	$ 28	$ (27)	$ 59	$ (66)