Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains, tax benefit (expense)	$ 73	$ 149	$ 154	$ 205
Net (gains) losses reclassified into earnings, tax expense (benefit)	(11)	(7)	(6)	(7)
Change in unrealized gains and losses, tax benefit (expense)	1	1	4	4
Net (gains) losses reclassified into earnings, tax expense (benefit)	(2)	(1)	(3)	(2)
Net change in cumulative translation adjustment and actuarial gains and losses, tax benefit (expense)	$ 0	$ 5	$ (1)	$ (34)