NET INCOME (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 26, 2019 USD ($) shares	Jan. 27, 2018 USD ($) shares	Jan. 26, 2019 USD ($) shares	Jan. 27, 2018 USD ($) shares
Class of Stock [Line Items]
Conversion of Stock, Conversion Ratio			1
Common Class A [Member]
Numerator:
Net income allocated, basic | $	$ 5,727	$ 7,174	$ 10,466	$ 9,452
Conversion of Class B to Class A shares | $	1,646	2,065	3,007	2,721
Effect of share-based compensation on allocated net income | $	0	0	0	0
Net income allocated, diluted | $	$ 7,373	$ 9,239	$ 13,473	$ 12,173
Denominator:
Weighted average shares outstanding, basic (in shares) | shares	9,723	9,714	9,727	9,718
Conversion of Class B to Class A shares (in shares) | shares	4,304	4,304	4,304	4,304
Dilutive effect of share-based compensation (in shares) | shares	0	0	0	0
Weighted average shares outstanding, diluted (in shares) | shares	14,027	14,018	14,031	14,022
Common Class B [Member]
Numerator:
Net income allocated, basic | $	$ 1,646	$ 2,065	$ 3,007	$ 2,721
Conversion of Class B to Class A shares | $	0	0	0	0
Effect of share-based compensation on allocated net income | $	0	0	0	0
Net income allocated, diluted | $	$ 1,646	$ 2,065	$ 3,007	$ 2,721
Denominator:
Weighted average shares outstanding, basic (in shares) | shares	4,304	4,304	4,304	4,304
Conversion of Class B to Class A shares (in shares) | shares	0	0	0	0
Dilutive effect of share-based compensation (in shares) | shares	0	0	0	0
Weighted average shares outstanding, diluted (in shares) | shares	4,304	4,304	4,304	4,304