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Debt Schedule of Debt (Details) - USD ($)	3 Months Ended
Debt Schedule of Debt (Details) - USD ($)	Oct. 29, 2016	Oct. 24, 2015	Jul. 30, 2016	Sep. 15, 2015	Sep. 09, 2015
Debt Instrument [Line Items]
Amortization of debt discount	$ 4,307,000	$ 1,780,000
Debt and capital lease obligations	792,001,000		$ 719,327,000
Less: current portion	(17,500,000)		(13,125,000)
Long-term debt	774,501,000		706,202,000
0.75% Convertible Senior Notes Due 2021
Debt Instrument [Line Items]
Amortization of debt discount	4,300,000	$ 1,800,000
Long-term Debt, Fair Value	413,300,000		458,700,000
Debt Instrument, Face Amount	$ 485,000,000		$ 485,000,000	$ 485,000,000
Debt, interest rate (in percent)	0.75%	0.75%	0.75%
Debt and capital lease obligations	$ 377,751,000		$ 373,077,000
Convertible Debt	377,751,000		373,077,000
Debt Instrument, Unamortized Discount	97,372,000		101,679,000
Unamortized Debt Issuance Expense	$ 9,877,000		$ 10,244,000	15,100,000
7.125% Senior Subordinated Notes Due 2021
Debt Instrument [Line Items]
Debt, interest rate (in percent)	7.125%		7.125%
Credit Agreement - Revolving facility (matures April 2020)
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 68,000,000		$ 0
Credit Agreement - Term Loan (matures April 2020)
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 350,000,000
Debt and capital lease obligations	346,250,000		$ 346,250,000
0.75% Convertible Notes Liability Component [Member]
Debt Instrument [Line Items]
Amortization of debt discount	$ 400,000	$ 100,000
Unamortized Debt Issuance Expense				$ 11,500,000
Incremental Facility, Minimum
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 150,000,000