Goodwill and Intangible Assets - Impairment Analysis (Details)	6 Months Ended	12 Months Ended
	Jan. 27, 2018	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Discount Rate	11.00%	11.00%	11.50%	11.50%
Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate	3.00%	3.00%	3.00%	2.50%
Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate	2.50%	2.00%	2.00%	1.50%