Fair Value (Fair Value On A Nonrecurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended
	Jan. 28, 2012	Jan. 28, 2012 Gains On Assets No Longer Held [Member]	Jan. 28, 2012 Fair Value, Inputs, Level 3 [Member]	Jan. 28, 2012 Fair Value, Inputs, Level 3 [Member]	Jan. 28, 2012 Fair Value Assets Measured On Nonrecurring Basis Change In Unrealized Gain Loss Included In G&A [Member] Assets Held-for-sale [Member]	Jan. 28, 2012 Fair Value Assets Measured On Nonrecurring Basis Change In Unrealized Gain Loss Included In G&A [Member] Assets Held-for-sale [Member]	Jan. 28, 2012 Fair Value, Inputs, Level 3 [Member] Investments In Privately Held Companies [Member]	Jan. 28, 2012 Fair Value, Inputs, Level 3 [Member] Investments In Privately Held Companies [Member]	Jan. 26, 2013 Fair Value, Measurements, Nonrecurring [Member] Net Carrying Value [Member] Fair Value, Inputs, Level 3 [Member]	Jan. 28, 2012 Fair Value, Measurements, Nonrecurring [Member] Net Carrying Value [Member] Fair Value, Inputs, Level 3 [Member]	Jan. 26, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Investments In Privately Held Companies [Member]	Jan. 26, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Investments In Privately Held Companies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in privately held companies									$ 60	$ 6
Property Held For Sale Fair Value Disclosure										39
Fair Value Nonrecurring Basis Gain Loss Recorded Total	$ 14	$ 14	$ (14)	$ (104)	$ (27)	$ (116)	$ (1)	$ (2)			$ (8)	$ (18)