Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Oct. 24, 2015	Jul. 25, 2015
Available-for-sale investments: [Line Items]
Amortized Cost	$ 53,010	$ 53,044
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	430	566
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(91)	(71)
Fair Value	53,349	53,539
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost	51,916	51,952
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	162	86
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(79)	(64)
Fair Value	51,999	51,974
Total fixed income securities | U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	27,409	29,904
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	63	41
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1)	(6)
Fair Value	27,471	29,939
Total fixed income securities | U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	3,606	3,662
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	11	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Fair Value	3,617	3,663
Total fixed income securities | Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,133	1,128
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	3	1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Fair Value	1,136	1,128
Total fixed income securities | Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	18,314	15,802
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	70	34
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(78)	(53)
Fair Value	18,306	15,783
Total fixed income securities | U.S. agency mortgage-backed securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,454	1,456
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	15	8
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(3)
Fair Value	1,469	1,461
Publicly traded equity securities [Member]
Available-for-sale investments: [Line Items]
Amortized Cost	1,094	1,092
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	268	480
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(12)	(7)
Fair Value	$ 1,350	$ 1,565