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	3 Months Ended
	Oct. 28, 2012	Oct. 30, 2011
Time Lapse, EPS And Strategic Performance Restricted Stock Units [Member]
Stock-based Compensation
Nonvested at beginning of period, Units	3,951
Granted, Units	1,832
Vested, Units	1,104
Forfeited, Units	59
Nonvested at end of period, Units	4,620
Nonvested at beginning of period, Weighted-Average Grant-Date Fair Value	$ 33.19
Granted, Weighted-Average Grant-Date Fair Value	$ 35.03	$ 32.38
Vested, Weighted-Average Grant-Date Fair Value	$ 33.44
Forfeited, Weighted Average Grant Date Fair Value	$ 33.04
Nonvested at end of period, Weighted-Average Grant-Date Fair Value	$ 33.89
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	(1,213)
Nonvested at end of period, Units	1,512
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	$ 33.94
Nonvested at end of period, Weighted-Average Grant-Date Fair Value	$ 41.86