Debt (Details) (USD $)	3 Months Ended	12 Months Ended
	Jul. 27, 2011	Apr. 27, 2011	Jan. 25, 2012	Jan. 25, 2012 Interest Rate Swap [Member]	Dec. 01, 2011 U.S. Dollar Remarketable Securities [Member]	Oct. 26, 2011 2.00% U.S. Dollar Notes due 2016 [Member]	Oct. 26, 2011 3.125% U.S. Dollar Notes due 2021 [Member]	Jul. 27, 2011 3.48% Private Placement Notes [Member]	Jul. 27, 2011 3.38% Private Placement Notes [Member]	Jul. 27, 2011 U.S. Dollar Notes due July 2011 [Member]	Jan. 25, 2012 Notes Payable, maturing March 15, 2012 [Member]
Debt Instrument [Line Items]
Notes, Face Amount					$ 119,000,000	$ 300,000,000	$ 400,000,000	$ 500,000,000	$ 100,000,000	$ 750,000,000	$ 600,000,000
Debt Instrument, Interest Rate, Stated Percentage		7.125%	7.125%		6.05%	2.00%	3.125%
Notional Amount of Interest Rate Derivative Instruments Not Designated as Hedging Instruments				119,000,000
Private placement notes, average interest rate								3.48%	3.38%
Total credit agreements supporting commercial paper borrowings	$ 1,500,000,000	$ 1,200,000,000
Maturity date	June 2016	April 2012