SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Income Per Share (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jul. 29, 2017 USD ($) class_common_stock $ / shares shares	Jul. 30, 2016 USD ($) $ / shares shares	Jul. 25, 2015 USD ($) $ / shares shares
Accounting Policies [Abstract]
Number of common stock classes | class_common_stock	2
Common stock cash dividends, percent Class A is entitled greater than Class B	54.00%
Class A Common Stock
Numerator:
Net income allocated, basic | $	$ 17,354	$ 18,967	$ 23,050
Conversion of Class B to Class A shares | $	5,025	5,563	6,885
Effect of share-based compensation on allocated net income | $	25	0	46
Net income allocated, diluted | $	$ 22,404	$ 24,530	$ 29,981
Denominator:
Weighted average shares outstanding, basic (in shares) | shares	9,663	9,567	9,459
Conversion of Class B to Class A shares (in shares) | shares	4,314	4,319	4,353
Dilutive effect of share-based compensation (in shares) | shares	27	0	48
Weighted average shares outstanding, diluted (in shares) | shares		13,886	13,860
Net income per share
Basic (in dollars per share) | $ / shares	$ 1.80	$ 1.98	$ 2.44
Diluted (in dollars per share) | $ / shares	$ 1.60	$ 1.77	$ 2.16
Class B Common Stock
Numerator:
Net income allocated, basic | $	$ 5,025	$ 5,563	$ 6,885
Conversion of Class B to Class A shares | $	0	0	0
Effect of share-based compensation on allocated net income | $	(4)	(3)	(23)
Net income allocated, diluted | $	$ 5,021	$ 5,560	$ 6,862
Denominator:
Weighted average shares outstanding, basic (in shares) | shares	4,314	4,319	4,353
Conversion of Class B to Class A shares (in shares) | shares	0	0	0
Dilutive effect of share-based compensation (in shares) | shares	0	0	0
Weighted average shares outstanding, diluted (in shares) | shares	4,314	4,319	4,353
Net income per share
Basic (in dollars per share) | $ / shares	$ 1.16	$ 1.29	$ 1.58
Diluted (in dollars per share) | $ / shares	$ 1.16	$ 1.29	$ 1.58