SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Aug. 01, 2015
Basis of Presentation
Days in fiscal year	364 days	364 days	364 days
Days in interim quarter	91 days	91 days	91 days
Cash Equivalents
Maximum original maturity of securities to be classified as cash equivalents (in months)	3 months
Property and equipment
Interest capitalized	$ 0	$ 400	$ 500
Property and equipment
Property and equipment, gross	1,027,845	979,011
Less accumulated depreciation and amortization	425,755	362,406
Net property and equipment	602,090	616,605
Depreciation expense	69,800	61,100	$ 55,000
Land
Property and equipment
Property and equipment, gross	52,989	52,641
Buildings and improvements
Property and equipment
Property and equipment, gross	396,733	403,822
Leasehold improvements
Property and equipment
Property and equipment, gross	138,466	136,758
Warehouse equipment
Property and equipment
Property and equipment, gross	173,591	163,494
Office equipment
Property and equipment
Property and equipment, gross	95,794	55,915
Computer software
Property and equipment
Property and equipment, gross	147,647	146,766
Motor vehicles
Property and equipment
Property and equipment, gross	4,657	4,597
Construction in progress
Property and equipment
Property and equipment, gross	$ 17,968	$ 15,018
Minimum | Buildings and improvements
Property and equipment
Original estimated useful lives	20 years	20 years
Minimum | Leasehold improvements
Property and equipment
Original estimated useful lives	5 years	5 years
Minimum | Warehouse equipment
Property and equipment
Original estimated useful lives	3 years	3 years
Minimum | Office equipment
Property and equipment
Original estimated useful lives	3 years	3 years
Minimum | Computer software
Property and equipment
Original estimated useful lives	3 years	3 years
Minimum | Motor vehicles
Property and equipment
Original estimated useful lives	3 years	3 years
Maximum | Buildings and improvements
Property and equipment
Original estimated useful lives	40 years	40 years
Maximum | Leasehold improvements
Property and equipment
Original estimated useful lives	20 years	20 years
Maximum | Warehouse equipment
Property and equipment
Original estimated useful lives	30 years	30 years
Maximum | Office equipment
Property and equipment
Original estimated useful lives	10 years	10 years
Maximum | Computer software
Property and equipment
Original estimated useful lives	7 years	7 years
Maximum | Motor vehicles
Property and equipment
Original estimated useful lives	7 years	7 years