Borrowings - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jan. 26, 2013	Jul. 30, 2011	Jul. 28, 2012
Subordinated Borrowing [Line Items]
Credit Facility Interest Rate	either (i) the higher of the Federal Funds rate plus 0.50%, Bank of America's "prime rate" as announced from time to time, or one-month LIBOR plus 1.00%, or (ii) LIBOR plus a margin that is based on the Company's senior debt credit ratings
ST debt financing program- Commercial paper announced value		$ 3,000,000,000
Commercial Paper	0		0
Notional amount of interest rate derivatives	4,250,000,000		4,250,000,000
Senior Notes Issued 2006 and 2011 [Member]
Subordinated Borrowing [Line Items]
Notional amount of interest rate derivatives	4,250,000,000
Unsecured Revolving Credit Facility [Member]
Subordinated Borrowing [Line Items]
Unsecured Revolving Credit Facility	3,000,000,000
Unsecured revolving credit facility maturity date	Feb. 17, 2017
Interest Rate- Federal Funds rate plus 0.5%	0.50%
Interest Rate- One-month LIBOR plus 1.00%	1.00%
Available increases under the credit facility	$ 2,000,000,000
Increase to maximum borrowing capacity- maturity date	Feb. 17, 2019