Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Jul. 30, 2016	Jul. 25, 2015
Available-for-sale investments: [Line Items]
Amortized Cost	$ 57,479	$ 53,044
Gross unrealized gains	703	566
Gross unrealized losses	(57)	(71)
Fair Value	58,125	53,539
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost	56,268	51,952
Gross unrealized gains	370	86
Gross unrealized losses	(17)	(64)
Fair Value	56,621	51,974
Total fixed income securities | U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	26,473	29,904
Gross unrealized gains	73	41
Gross unrealized losses	(2)	(6)
Fair Value	26,544	29,939
Total fixed income securities | U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	2,809	3,662
Gross unrealized gains	8	2
Gross unrealized losses	0	(1)
Fair Value	2,817	3,663
Total fixed income securities | Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,096	1,128
Gross unrealized gains	4	1
Gross unrealized losses	0	(1)
Fair Value	1,100	1,128
Total fixed income securities | Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	24,044	15,802
Gross unrealized gains	263	34
Gross unrealized losses	(15)	(53)
Fair Value	24,292	15,783
Total fixed income securities | Mortgage-backed Securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,846	1,456
Gross unrealized gains	22	8
Gross unrealized losses	0	(3)
Fair Value	1,868	1,461
Publicly traded equity securities [Member]
Available-for-sale investments: [Line Items]
Amortized Cost	1,211	1,092
Gross unrealized gains	333	480
Gross unrealized losses	(40)	(7)
Fair Value	$ 1,504	$ 1,565