SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jul. 25, 2020	Jul. 27, 2019
Class A Common Stock
Numerator:
Net income allocated, basic	$ 18,857	$ 19,341
Conversion of Class B to Class A shares	5,363	5,538
Effect of share-based compensation on allocated net income	0	0
Net income allocated, diluted	$ 24,220	$ 24,879
Denominator:
Weighted average shares outstanding, basic (in shares)	9,794	9,747
Conversion of Class B to Class A shares (in shares)	4,294	4,296
Dilutive effect of share-based compensation (in shares)	0	0
Weighted average shares outstanding, diluted (in shares)	14,088	14,043
Net income per share
Basic (in dollars per share)	$ 1.93	$ 1.98
Diluted (in dollars per share)	$ 1.72	$ 1.77
Class B Common Stock
Numerator:
Net income allocated, basic	$ 5,363	$ 5,538
Conversion of Class B to Class A shares	0	0
Effect of share-based compensation on allocated net income	0	(1)
Net income allocated, diluted	$ 5,363	$ 5,537
Denominator:
Weighted average shares outstanding, basic (in shares)	4,294	4,296
Conversion of Class B to Class A shares (in shares)	0	0
Dilutive effect of share-based compensation (in shares)	0	0
Weighted average shares outstanding, diluted (in shares)	4,294	4,296
Net income per share
Basic (in dollars per share)	$ 1.25	$ 1.29
Diluted (in dollars per share)	$ 1.25	$ 1.29