Stock-based Compensation (Time-Lapse Restricted Stock Units, EPS Performance Restricted Stock Units And Strategic Performance Restricted Stock Units And TSR Performance Restricted Stock Units) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jan. 27, 2013	Jan. 29, 2012
Time Lapse, EPS And Strategic Performance Restricted Stock Units [Member]
Stock-based Compensation
Nonvested at beginning of period, Units	3,951
Granted, Units	1,867
Vested, Units	(1,113)
Forfeited, Units	(125)
Nonvested at end of period, Units	4,580
Nonvested at beginning of period, Weighted-Average Grant-Date Fair Value	$ 33.19
Granted, Weighted-Average Grant-Date Fair Value	$ 35.04	$ 32.38
Vested, Weighted-Average Grant-Date Fair Value	$ 33.44
Forfeited, Weighted Average Grant Date Fair Value	$ 33.35
Nonvested at end of period, Weighted-Average Grant-Date Fair Value	$ 33.90
TSR Performance Restricted Stock/Units [Member]
Stock-based Compensation
Nonvested at beginning of period, Units	2,143
Granted, Units	582
Vested, Units	0
Forfeited, Units	(1,232)
Nonvested at end of period, Units	1,493
Nonvested at beginning of period, Weighted-Average Grant-Date Fair Value	$ 37.94
Granted, Weighted-Average Grant-Date Fair Value	$ 39.76
Vested, Weighted-Average Grant-Date Fair Value	$ 0
Forfeited, Weighted Average Grant Date Fair Value	$ 34.06
Nonvested at end of period, Weighted-Average Grant-Date Fair Value	$ 41.86