RELATED PARTY INFORMATION - WAKEFERN (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 27, 2019	Jul. 28, 2018
Related Party Transaction [Line Items]
Related party transaction amount	$ 43	$ 114
Maturity of notes receivable from Wakefern	$ 24,937	22,172
Wakefern
Related Party Transaction [Line Items]
Ownership interest in Wakefern	12.50%
Purchase obligation, as a percentage of merchandise requirements	85.00%
Purchase obligation period	10 years
Percentage of stockholders to request termination	75.00%
Indebtedness to Wakefern	$ 846
Vendor allowances and rebates	31,412	28,536
Support services incurred charges	33,581	33,037
Demand deposits invested at related party Wakefern	73,879	63,413
Interest income earned on investments related entity	5,215	$ 3,806
Wakefern | Related Party Note Receivable Maturing August 2022
Related Party Transaction [Line Items]
Notes receivable from Wakefern	$ 24,687
Basis spread on variable rate (as a percent)	1.25%
Wakefern | Related Party Note Receivable Maturing February 2024
Related Party Transaction [Line Items]
Notes receivable from Wakefern	$ 25,521
Basis spread on variable rate (as a percent)	0.75%
Wakefern | Insure-Rite Ltd.
Related Party Transaction [Line Items]
Investment in Insure-Rite, Ltd	7.70%
Stock Subscriptions Outstanding, Payments Due In 2021
Related Party Transaction [Line Items]
Related party transaction amount	$ 130
Stock Subscriptions Outstanding, Payments Due In 2022
Related Party Transaction [Line Items]
Related party transaction amount	171
Stock Subscriptions Outstanding, Payments Due In 2023
Related Party Transaction [Line Items]
Related party transaction amount	161
Stock Subscriptions Outstanding, Payments Due In 2024
Related Party Transaction [Line Items]
Related party transaction amount	154
Stock Subscriptions Outstanding, Payments Due After 2024
Related Party Transaction [Line Items]
Related party transaction amount	187
Per Store Investment, Maximum | Wakefern
Related Party Transaction [Line Items]
Related party transaction amount	950
Per Store Investment, Increase | Wakefern
Related Party Transaction [Line Items]
Related party transaction amount	25
Per Store Investment, Additions | Wakefern
Related Party Transaction [Line Items]
Related party transaction amount	$ 625