Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Oct. 28, 2017	Jul. 29, 2017
Schedule of Investments [Line Items]
Amortized Cost	$ 59,988	$ 58,225
Gross Unrealized Gains	817	762
Gross Unrealized Losses	(260)	(203)
Fair Value	60,545	58,784
Net unsettled available-for-sale investments, purchases (sales)	95	(30)
Total fixed income securities
Schedule of Investments [Line Items]
Amortized Cost	58,854	57,045
Gross Unrealized Gains	164	208
Gross Unrealized Losses	(254)	(176)
Fair Value	58,764	57,077
Total fixed income securities | U.S. government securities
Schedule of Investments [Line Items]
Amortized Cost	20,564	19,880
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(93)	(60)
Fair Value	20,471	19,823
Total fixed income securities | U.S. government agency securities
Schedule of Investments [Line Items]
Amortized Cost	1,923	2,057
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(6)	(5)
Fair Value	1,917	2,052
Total fixed income securities | Non-U.S. government and agency securities
Schedule of Investments [Line Items]
Amortized Cost	358	389
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	357	388
Total fixed income securities | Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	31,999	31,626
Gross Unrealized Gains	162	202
Gross Unrealized Losses	(131)	(93)
Fair Value	32,030	31,735
Total fixed income securities | U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	2,095	2,037
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(23)	(17)
Fair Value	2,074	2,023
Total fixed income securities | Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	1,775	996
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	1,775	996
Total fixed income securities | Certificates of deposit
Schedule of Investments [Line Items]
Amortized Cost	140	60
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	140	60
Publicly traded equity securities
Schedule of Investments [Line Items]
Amortized Cost	1,134	1,180
Gross Unrealized Gains	653	554
Gross Unrealized Losses	(6)	(27)
Fair Value	$ 1,781	$ 1,707