Basis of Presentation and Accounting Policies (Details) - segment	3 Months Ended	12 Months Ended
	Jan. 28, 2017	Jul. 29, 2017	Jul. 30, 2016
Segment Reporting Information [Line Items]
Number of reportable segments	1
Fiscal period duration			371 days
Subsequent Event [Member]
Segment Reporting Information [Line Items]
Fiscal period duration		364 days