Other Income, Net (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jan. 27, 2018	Jan. 28, 2017	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Other Income and Expenses [Abstract]
Gain on sale of fixed assets	$ 7,217		$ 14,866	$ 9,806	$ 7,110
Miscellaneous expense, net	(992)		(2,086)	627	1,181
Total other income, net	6,225	$ 1,946	12,780	10,433	$ 8,291
Other financial services costs	$ 1,400		$ 3,200	$ 200