Investments (Available-For-Sale Investments With Gross Unrealized Losses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 26, 2014	Jul. 27, 2013
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	$ 10,044	$ 12,573
Gross unrealized losses, less than 12 months	(26)	(70)
Fair value of investment securities with unrealized losses12 months or greater	558	4
Gross unrealized losses, 12 months or greater	(4)	0
Fair value of investment securities with unrealized losses	10,602	12,577
Total gross unrealized losses	(30)	(70)
Publicly traded equity securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	132	278
Gross unrealized losses, less than 12 months	(10)	(4)
Fair value of investment securities with unrealized losses12 months or greater	0	0
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	132	278
Total gross unrealized losses	(10)	(4)
Total fixed income securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	9,912	12,295
Gross unrealized losses, less than 12 months	(16)	(66)
Fair value of investment securities with unrealized losses12 months or greater	558	4
Gross unrealized losses, 12 months or greater	(4)	0
Fair value of investment securities with unrealized losses	10,470	12,299
Total gross unrealized losses	(20)	(66)
Total fixed income securities | U.S. government securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	7,676	7,865
Gross unrealized losses, less than 12 months	(12)	(13)
Fair value of investment securities with unrealized losses12 months or greater	45	0
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	7,721	7,865
Total gross unrealized losses	(12)	(13)
Total fixed income securities | U.S. government agency securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months		294
Gross unrealized losses, less than 12 months		(1)
Fair value of investment securities with unrealized losses12 months or greater		0
Gross unrealized losses, 12 months or greater		0
Fair value of investment securities with unrealized losses		294
Total gross unrealized losses		(1)
Total fixed income securities | Non-U.S. government and agency securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	361	432
Gross unrealized losses, less than 12 months	(1)	(2)
Fair value of investment securities with unrealized losses12 months or greater	22	0
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	383	432
Total gross unrealized losses	(1)	(2)
Total fixed income securities | Corporate debt securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	1,875	3,704
Gross unrealized losses, less than 12 months	(3)	(50)
Fair value of investment securities with unrealized losses12 months or greater	491	4
Gross unrealized losses, 12 months or greater	(4)	0
Fair value of investment securities with unrealized losses	2,366	3,708
Total gross unrealized losses	$ (7)	$ (50)