Income Taxes (Income Before Provision For Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 2,963	$ 3,306	$ 5,916	$ 6,443
Provision for income taxes	$ 615	$ 159	$ 1,246	$ 866
Effective tax rate	20.80%	4.80%	21.10%	13.40%