Investments (Summary Of Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 25, 2014	Jul. 26, 2014
Available-for-sale investments: [Line Items]
Amortized Cost	$ 47,038	$ 44,619
Gross Unrealized Gains	703	759
Gross Unrealized Losses	(21)	(30)
Fair Value	47,720	45,348
Publicly traded equity securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,263	1,314
Gross Unrealized Gains	545	648
Gross Unrealized Losses	(11)	(10)
Fair Value	1,797	1,952
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost	45,775	43,305
Gross Unrealized Gains	158	111
Gross Unrealized Losses	(10)	(20)
Fair Value	45,923	43,396
Total fixed income securities | U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	32,343	31,717
Gross Unrealized Gains	71	29
Gross Unrealized Losses	0	(12)
Fair Value	32,414	31,734
Total fixed income securities | U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,338	1,062
Gross Unrealized Gains	3	1
Gross Unrealized Losses	0	0
Fair Value	1,341	1,063
Total fixed income securities | Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,049	860
Gross Unrealized Gains	2	2
Gross Unrealized Losses	0	(1)
Fair Value	1,051	861
Total fixed income securities | Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	10,170	9,092
Gross Unrealized Gains	73	74
Gross Unrealized Losses	(10)	(7)
Fair Value	10,233	9,159
Total fixed income securities | U.S. agency mortgage-backed securities
Available-for-sale investments: [Line Items]
Amortized Cost	875	574
Gross Unrealized Gains	9	5
Gross Unrealized Losses	0	0
Fair Value	$ 884	$ 579