Restructuring And Other Charges (Schedule Of Activities Related To Restructuring And Other Charges) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jan. 26, 2013	Jul. 28, 2012	Jul. 30, 2011
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Period Expense	$ 72	$ 353	$ 799
Change In Estimate Of Restructuring Reserves		(49)
Restructuring Reserve, Settled with Cash	(149)	(436)	(449)
Restructuring Reserve, Settled without Cash	(3)	(20)	(88)
Restructuring Reserve	30	110	262
Special Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Period Expense	0	0	453
Change In Estimate Of Restructuring Reserves		0
Restructuring Reserve, Settled with Cash	0	(17)	(436)
Restructuring Reserve, Settled without Cash	0	0	0
Restructuring Reserve	0	0	17
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Period Expense	77	299	247
Change In Estimate Of Restructuring Reserves		(49)
Restructuring Reserve, Settled with Cash	(139)	(401)	(13)
Restructuring Reserve, Settled without Cash	0	0	0
Restructuring Reserve	21	83	234
Goodwill And Intangible Assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Period Expense	0	0	71
Change In Estimate Of Restructuring Reserves		0
Restructuring Reserve, Settled with Cash	0	0	0
Restructuring Reserve, Settled without Cash	0	0	(71)
Restructuring Reserve	0	0	0
Other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Period Expense	(5)	54	28
Change In Estimate Of Restructuring Reserves		0
Restructuring Reserve, Settled with Cash	(10)	(18)	0
Restructuring Reserve, Settled without Cash	(3)	(20)	(17)
Restructuring Reserve	$ 9	$ 27	$ 11