Share-Based Compensation, Nonvested Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2020	Aug. 02, 2019	Aug. 03, 2018
Nonvested Stock Awards [Member]
Nonvested stock, shares [Roll Forward]
Unvested, beginning of period (in shares)	52,583
Granted (in shares)	27,779
Vested (in shares)	(20,307)
Forfeited (in shares)	(300)
Unvested, end of period (in shares)	59,755	52,583
Nonvested stock, weighted-average grant date fair value [Roll Forward]
Unvested, beginning of period (in dollars per share)	$ 147.17
Granted (in dollars per share)	161.92
Vested (in dollars per share)	151.88
Forfeited (in dollars per share)	164.29
Unvested, end of period (in dollars per share)	$ 152.34	$ 147.17
Total fair value of nonvested stock	$ 3,084	$ 5,119	$ 5,976
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
2020 LTPP [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Nonvested stock earned (in shares)	10,451
2020 LTPP [Member] | Minimum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2020
Vesting period	2 years
2020 LTPP [Member] | Maximum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2021
Vesting period	3 years
2019 LTPP [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Nonvested stock earned (in shares)	22,767
2019 LTPP [Member] | Minimum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2019
Vesting period	2 years
2019 LTPP [Member] | Maximum [Member]
Nonvested Stock Awards and Nonvested Stock Units [Abstract]
Performance period	2020
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	1.60%	2.90%	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%