Share-Based Compensation, Nonvested Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Aug. 03, 2018	Jul. 28, 2017	Jul. 29, 2016
Nonvested Stock Awards [Member]
Nonvested stock, shares [Roll Forward]
Unvested, beginning of period (in shares)	32,017
Granted (in shares)	51,406
Vested (in shares)	(38,889)
Forfeited (in shares)	(2,776)
Unvested, end of period (in shares)	41,758	32,017
Nonvested stock, weighted-average grant date fair value [Roll Forward]
Unvested, beginning of period (in dollars per share)	$ 139.04
Granted (in dollars per share)	154.28
Vested (in dollars per share)	153.66
Forfeited (in dollars per share)	145.92
Unvested, end of period (in dollars per share)	$ 143.73	$ 139.04
Total fair value of nonvested stock	$ 5,976	$ 14,700	$ 8,418
Nonvested Stock Awards [Member] | Minimum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Vesting period	1 year
Nonvested Stock Awards [Member] | Maximum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Vesting period	5 years
2018 LTPP [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Nonvested stock earned (in shares)	8,892
2018 LTPP [Member] | Minimum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2018
Vesting period	2 years
2018 LTPP [Member] | Maximum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2019
Vesting period	3 years
2017 LTPP [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Nonvested stock earned (in shares)	23,511
2017 LTPP [Member] | Minimum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2017
Vesting period	2 years
2017 LTPP [Member] | Maximum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2018
Vesting period	3 years
Omnibus Plan 2010 [Member] | Nonvested Stock Units [Member]
Nonvested stock, weighted-average grant date fair value [Roll Forward]
Award performance period	3 years
Measurement period for average stock prices in consecutive calendar days	60 days
Measurement period for average stock prices prior to first business day of performance period	30 days
Measurement period for average stock prices after first business day of performance period	30 days
Risk-free interest rate for nonvested stock units granted minimum		1.00%
Risk-free interest rate for nonvested stock units granted maximum		1.40%
Risk-free interest rate for nonvested stock units granted	1.60%
Omnibus Plan 2010 [Member] | Nonvested Stock Units [Member] | Minimum [Member]
Nonvested stock, weighted-average grant date fair value [Roll Forward]
Percentage of shares of target award that may be awarded	75.00%
Omnibus Plan 2010 [Member] | Nonvested Stock Units [Member] | Maximum [Member]
Nonvested stock, weighted-average grant date fair value [Roll Forward]
Percentage of shares of target award that may be awarded	125.00%