Derivative Instruments (Interest Rate Designated As Cash Flow Hedge) (Details) (USD $) In Millions, unless otherwise specified	Jan. 28, 2012	Jul. 30, 2011	Jan. 29, 2011
Derivative [Line Items]
Notional amount of cash flow hedge derivative	$ 175	$ 57	$ 595
Fixed Rate 6.125 Percent Notes Due December 2012 [Member]
Derivative [Line Items]
Notional amount of cash flow hedge derivative	0		57
Fixed Rate 5.25 Percent Notes Due November 2014 [Member]
Derivative [Line Items]
Notional amount of cash flow hedge derivative	0		213
Fixed Rate 6.90 Percent Notes Due July 2017 [Member]
Derivative [Line Items]
Notional amount of cash flow hedge derivative	$ 175		$ 325