Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Oct. 29, 2016	Oct. 24, 2015
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains, tax expense (benefit)	$ 81	$ 56
Net (gains) losses reclassified into earnings, tax expense (benefit)	5	0
Change in unrealized gains and losses, tax expense (benefit)	3	3
Net (gains) losses reclassified into earnings, tax expense (benefit)	(1)	(1)
Net change in cumulative translation adjustment and actuarial gains and losses, tax expense (benefit)	$ (1)	$ (39)