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Debt - Components of the Convertible Notes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 28, 2018	Jul. 29, 2017	Jul. 28, 2018	Jul. 29, 2017	Jan. 27, 2018	Sep. 15, 2015
Debt Instrument [Line Items]
Equity component of 0.75% senior convertible notes due 2021, net	$ 112,600,000		$ 112,600,000
Amortization of debt discount			9,422,000	$ 8,924,000
Estimate of Fair Value Measurement
Debt Instrument [Line Items]
Debt instrument, face amount	545,722,000		545,722,000		$ 659,649,000
Less: Debt discount and debt issuance costs	(72,432,000)		(72,432,000)		(82,751,000)
Net carrying amount of Notes	473,290,000		473,290,000		576,898,000
0.75% Convertible Senior Notes Due 2021
Debt Instrument [Line Items]
Debt instrument, face amount	485,000,000		485,000,000		485,000,000	$ 485,000,000.0
Debt Instrument, Unamortized Discount	(65,477,000)		(65,477,000)		(74,899,000)
Debt issuance cost	(6,955,000)		(6,955,000)		(7,852,000)
Net carrying amount of Notes	412,568,000		412,568,000		$ 402,249,000
Amortization of debt discount	$ 4,800,000	$ 4,500,000	$ 9,400,000	$ 8,900,000