Income Taxes (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Jan. 26, 2019	Oct. 27, 2018	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018	Jul. 28, 2018
Income Tax Contingency [Line Items]
Benefit for provision for income taxes	$ (521)		$ (12,010)	$ (881)	$ (12,578)
Tax Cuts and Jobs Act of 2017, provisional tax expense						$ 10,400
Tax Cuts and Jobs Act, provisional tax expense		$ 58		10,500
Tax Cuts and Jobs Act, transition tax expense (benefit)				8,200
Tax Cuts And Jobs Act, tax expense for foreign withholding tax				1,200
Tax Cuts and Jobs Act, re-measurement of net deferred tax assets				1,100
Tax Cuts and Jobs Act, transition tax benefit, foreign dividends				900
Unrecognized tax benefits	1,800			1,800
Unrecognized tax benefits that would impact effective tax rate	1,600			1,600
Unrecognized tax benefit that could be reduced in next 12 months	50			50
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Income Tax Contingency [Line Items]
Benefit for provision for income taxes	$ 152			$ 152