Debt (Details) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended				6 Months Ended
	Oct. 29, 2017 USD ($)	Jul. 30, 2017 USD ($) $ / shares shares		Jul. 31, 2016 USD ($)	Jul. 30, 2017 USD ($) $ / shares shares		Jul. 31, 2016 USD ($)	Jul. 28, 2017 $ / shares	Jan. 29, 2017 USD ($) shares
Debt Instrument
Stated interest rate, Convertible Notes		1.00%			1.00%
Repayment of Convertible Notes		$ 136,000
Convertible Notes - Face Amount		$ 86,000			$ 86,000				$ 827,000
Shares issued - Convertible Notes | shares		5
Loss on early debt conversions		$ 3,000			17,000		$ 0
Closing stock price | $ / shares								$ 164.39
If-converted value in excess of principal - Convertible Notes		$ 619,000
Conversion ratio - Convertible Notes		49.8804
Principal amount of Convertible Notes		$ 1			$ 1
Conversion price - Convertible Notes | $ / shares		$ 20.0480			$ 20.0480
Extinguishment of Debt, to date		$ 1,410,000			$ 1,410,000
Terms of conversion feature - Convertible Notes					during any fiscal quarter, if the last reported sale price of the common stock for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price on each applicable trading day, the Convertible Notes become convertible at the holders' option
Initial debt component - Convertible Notes		1,350,000
Initial carrying amount of equity component		126,000			$ 126,000
Purchaser's discount of Convertible Notes		23,000
Initial unamortized debt discount at issuance		$ 148,000
Effective interest rate - Convertible Notes		3.15%			3.15%
Unamortized debt discount - Convertible Notes		$ (2,000)	[1]		$ (2,000)	[1]			(31,000)
Convertible Notes, net carrying amount		84,000			$ 84,000				$ 796,000
Remaining discount amortization period					1 year 4 months 2 days
Coupon interest expense, Convertible Notes		0		$ 4,000	$ 0		8,000
Amortization of Debt Issuance Costs and Discounts		1,000		7,000	2,000		14,000
Total interest expense related to Convertible Notes		$ 1,000		$ 11,000	$ 2,000		$ 22,000
Note Hedges Strike Price | $ / shares		$ 20.0480			$ 20.0480
Shares received from Note Hedges | shares		5			5
Number of warrants terminated | shares		12			12				63
Total number of shares issued related to terminated Warrants | shares		10			10				48
Proceeds from issuance of debt		$ 1,980,000
Unamortized discount and issuance costs		(16,000)			$ (16,000)				$ (17,000)
Long-term debt, net carrying amount		1,984,000			1,984,000				1,983,000
2021 Notes [Member]
Debt Instrument
Long-term Debt, Gross		$ 1,000,000			$ 1,000,000				1,000,000
Long-term Debt, Stated interest rate		2.20%			2.20%
Expected remaining term - Long-term debt		4 years 1 month 18 days
Effective interest rate - Long-term debt		2.38%
2026 Notes [Member]
Debt Instrument
Long-term Debt, Gross		$ 1,000,000			$ 1,000,000				$ 1,000,000
Long-term Debt, Stated interest rate		3.20%			3.20%
Expected remaining term - Long-term debt		9 years 1 month 19 days
Effective interest rate - Long-term debt		3.31%
Subsequent Event [Member]
Debt Instrument
Subsequent repayment of Convertible debt	$ 62,000

[1] As of July 30, 2017, the remaining period over which the unamortized debt discount will be amortized is 1.3 years.