Derivative Instruments and Hedging Activities, Pre-tax Effects of Derivative Instruments on AOCL and Income (Details) - Interest Rate Swaps [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016	Jul. 29, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (loss) recognized in AOCL on derivatives (effective portion)			$ 17,500		$ (16,188)
Ineffectiveness recorded in earnings on interest rate cash flow hedge			0	$ 0
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from AOCL into income (effective portion)	$ 1,118	$ 1,444	$ 2,361	$ 2,891