Employee Benefit Plans - Narratives (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Oct. 31, 2016	Jan. 27, 2018	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015	Nov. 30, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution maximum annual contribution for employee		75.00%
Defined contribution employer match		30.00%
Defined contribution employer match		5.00%
Employer contribution amount		$ 1.7	$ 5.0	$ 4.8	$ 4.0
Multiemployer plan periodic withdraw liability						$ 0.1
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan contribution		5.00%
Multiemployer plans, red zone threshold		65.00%
Multiemployer plans, yellow zone threshold		80.00%
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer plans, yellow zone threshold		65.00%
Multiemployer plans, green zone threshold		80.00%
The Plan (EIN 13-6123601)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Claim amount	$ 13.0