Property and Equipment - Depreciation Expense and Repairs (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jan. 27, 2018	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 72,961	$ 123,125	$ 105,514	$ 79,331
Repairs and maintenance expense	$ 16,438	$ 31,272	$ 29,487	$ 22,054