Borrowings (Narrative) (Details) (USD $)	9 Months Ended	12 Months Ended
	Apr. 28, 2012	Jul. 30, 2011
Debt Instrument [Line Items]
Short-term debt financing program, announced value	$ 3,000,000,000	$ 3,000,000,000
Increase to maximum borrowing capacity-Maturity Date	Feb. 17, 2019
Notional amount of interest rate derivatives	0	0
Senior Notes Issued March 2011 [Member]
Debt Instrument [Line Items]
Notional amount of interest rate derivatives	4,250,000,000
Unsecured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	3,000,000,000
Maturity date	February 17, 2017
LIBOR plus margin based on the Company's senior debt S&P or Moody's credit ratings description	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
Increase to maximum borrowing capacity	$ 2,000,000,000
Interest Rate-Federal Funds rate plus 0.50%	0.50%
Interest rate-one-month LIBOR plus 1.00%	1.00%