Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Oct. 28, 2017	Oct. 29, 2016
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains, tax benefit (expense)	$ (23)	$ 81
Net (gains) losses reclassified into earnings, tax expense (benefit)	10	5
Change in unrealized gains and losses, tax benefit (expense)	(1)	3
Net (gains) losses reclassified into earnings, tax expense (benefit)	2	(1)
Net change in cumulative translation adjustment and actuarial gains and losses, tax benefit (expense)	$ (2)	$ (1)