Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Jul. 25, 2015	Jul. 26, 2014
Available-for-sale investments: [Line Items]
Amortized Cost		$ 44,619
Publicly traded equity securities
Available-for-sale investments: [Line Items]
Amortized Cost		1,314
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost		43,305
Total fixed income securities | U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	$ 29,904	31,717
Gross unrealized gains	41	29
Gross unrealized losses	(6)	(12)
Fair Value	29,939	31,734
Total fixed income securities | U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	3,662	1,062
Gross unrealized gains	2	1
Gross unrealized losses	(1)	0
Fair Value	3,663	1,063
Total fixed income securities | Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,128	860
Gross unrealized gains	1	2
Gross unrealized losses	(1)	(1)
Fair Value	1,128	861
Total fixed income securities | Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	15,802	9,092
Gross unrealized gains	34	74
Gross unrealized losses	(53)	(7)
Fair Value	15,783	9,159
Total fixed income securities | Asset-backed Securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,456	574
Gross unrealized gains	8	5
Gross unrealized losses	(3)	0
Fair Value	$ 1,461	$ 579