Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Jan. 23, 2016	Jul. 25, 2015
Available-for-sale investments: [Line Items]
Amortized Cost	$ 54,066	$ 53,044
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	236	566
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(241)	(71)
Fair Value	54,061	53,539
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost	52,748	51,952
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	60	86
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(178)	(64)
Fair Value	52,630	51,974
Total fixed income securities | U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	28,242	29,904
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	18	41
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(16)	(6)
Fair Value	28,244	29,939
Total fixed income securities | U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	3,492	3,662
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	3	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(2)	(1)
Fair Value	3,493	3,663
Total fixed income securities | Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,152	1,128
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1	1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1)	(1)
Fair Value	1,152	1,128
Total fixed income securities | Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	18,410	15,802
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	29	34
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(158)	(53)
Fair Value	18,281	15,783
Total fixed income securities | U.S. agency mortgage-backed securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,452	1,456
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	9	8
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1)	(3)
Fair Value	1,460	1,461
Publicly traded equity securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,318	1,092
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	176	480
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(63)	(7)
Fair Value	$ 1,431	$ 1,565