NET INCOME (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016
Common Class A [Member]
Numerator:
Net income allocated, basic	$ 4,548	$ 4,755	$ 7,664	$ 8,108
Conversion of Class B to Class A shares	1,327	1,395	2,239	2,379
Effect of share-based compensation on allocated net income	6	0	8	0
Net income allocated, diluted	$ 5,881	$ 6,150	$ 9,911	$ 10,487
Denominator:
Weighted average shares outstanding, basic (in shares)	9,613	9,561	9,603	9,569
Conversion of Class B to Class A shares (in shares)	4,319	4,319	4,319	4,319
Dilutive effect of share-based compensation (in shares)	52	0	50	0
Weighted average shares outstanding, diluted (in shares)	13,984	13,880	13,972	13,888
Common Class B [Member]
Numerator:
Net income allocated, basic	$ 1,327	$ 1,395	$ 2,239	$ 2,379
Conversion of Class B to Class A shares	0	0	0	0
Effect of share-based compensation on allocated net income	(3)	0	(3)	0
Net income allocated, diluted	$ 1,324	$ 1,395	$ 2,236	$ 2,379
Denominator:
Weighted average shares outstanding, basic (in shares)	4,319	4,319	4,319	4,319
Conversion of Class B to Class A shares (in shares)	0	0	0	0
Dilutive effect of share-based compensation (in shares)	0	0	0	0
Weighted average shares outstanding, diluted (in shares)	4,319	4,319	4,319	4,319