SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) $ in Thousands	12 Months Ended
	Jul. 25, 2020 USD ($) segment store	Jul. 27, 2019 USD ($)	Jul. 28, 2019 USD ($)	Jun. 24, 2019 store	Jul. 28, 2018 USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment	1
Business Acquisition [Line Items]
Number of stores acquired | store	35
Cash and Cash Equivalents [Abstract]
Credit and debit card receivables	$ 11,535	$ 8,061
Inventory Disclosure [Abstract]
Percentage of LIFO inventory	63.00%
LIFO reserve inventory	$ 15,101	14,512
Leases [Abstract]
Operating lease assets	309,756
Present value of lease liabilities	317,148
Adjustment to retained earnings from adoption of ASU 2016-02	332,320	318,672			$ 303,145
Financing obligations	(23,544)
Net assets for leases	(269,741)	(224,890)
Marketing and Advertising Expense [Abstract]
Advertising expense	$ 10,904	11,705
Accounting Standards Update 2016-02
Leases [Abstract]
Operating lease assets			$ 99,415
Present value of lease liabilities			111,139
Financing obligations			17,442
Net assets for leases			12,543
Buildings
Property, Plant and Equipment [Line Items]
Useful life	30 years
Store fixtures and equipment
Property, Plant and Equipment [Line Items]
Useful life	10 years
Vehicles
Property, Plant and Equipment [Line Items]
Useful life	3 years
Revision of Prior Period, Accounting Standards Update, Adjustment
Leases [Abstract]
Adjustment to retained earnings from adoption of ASU 2016-02			$ 3,514
Wakefern
Related Party Transaction [Line Items]
Demand deposits invested at related party Wakefern	$ 76,259	$ 73,879
Gourmet Garage Specialty Markets
Business Acquisition [Line Items]
Number of stores acquired | store	3			3