Basis of Presentation and Accounting Policies (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 23, 2016 USD ($)	Apr. 25, 2015 USD ($)	Apr. 23, 2016 USD ($) segment	Apr. 25, 2015 USD ($)	Jul. 30, 2016	Jul. 25, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			1
Prepaid Expense and Other Assets	$ 17,300		$ 17,300			$ 13,600
Deferred Finance Costs, Net	7,200		7,200			11,600
Insurance recoveries/receivables related to accrued claims	5,900		5,900			9,500
Contract revenues	664,645	$ 492,363	1,883,383	$ 1,443,833
Restricted cash	5,000		$ 5,000			4,500
Measurement period			12 months
Investments and other noncurrent assets	4,000		$ 4,000			$ 4,000
Fiscal period duration						364 days
Subsequent Event [Member]
Segment Reporting Information [Line Items]
Fiscal period duration					371 days
Non-Current Other Assets
Segment Reporting Information [Line Items]
Insurance recoveries/receivables related to accrued claims	5,900		5,900			$ 8,900
Canada
Segment Reporting Information [Line Items]
Contract revenues	$ 900	$ 2,000	$ 5,500	$ 9,800