Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	Aug. 02, 2013	Aug. 03, 2012
Financial Instruments
Long-term debt carrying value (excluding capitalized lease obligations)	$ 8,647	$ 9,194
Long-term debt fair value (excluding capitalized lease obligations)	9,479	10,774
Unsecured Notes [Member]
Financial Instruments
Long-term debt carrying value (excluding capitalized lease obligations)	8,629	9,175
Unsecured Notes [Member] | Fair Value (Level 1) [Member]
Financial Instruments
Long-term debt fair value (excluding capitalized lease obligations)	9,459	10,751
Mortgage Notes [Member]
Financial Instruments
Long-term debt carrying value (excluding capitalized lease obligations)	18	19
Mortgage Notes [Member] | Fair Value (Level 2) [Member]
Financial Instruments
Long-term debt fair value (excluding capitalized lease obligations)	$ 20	$ 23