Intangible Assets (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 28, 2013	Jul. 29, 2012	Jul. 28, 2013	Jul. 29, 2012	Jan. 27, 2013
Amortizable intangible assets components
Gross Carrying Amount	$ 625,200,000		$ 625,200,000		$ 579,041,000
Accumulated Amortization	(302,680,000)		(302,680,000)		(266,709,000)
Net Carrying Amount	322,520,000		322,520,000		312,332,000
Amortization expense associated with intangible assets
Amortization expense	18,600,000	17,200,000	36,000,000	33,800,000
Future amortization expense associated with intangible assets
Remainder of fiscal 2014	33,300,000		33,300,000
Fiscal 2015	76,400,000		76,400,000
Fiscal 2016	76,500,000		76,500,000
Fiscal 2017	54,100,000		54,100,000
Fiscal 2018	46,000,000		46,000,000
Fiscal 2019 and fiscal years subsequent of fiscal 2019	36,200,000		36,200,000
Acquisition-related intangible assets
Amortizable intangible assets components
Gross Carrying Amount	173,039,000		173,039,000		172,039,000
Accumulated Amortization	(104,288,000)		(104,288,000)		(96,389,000)
Net Carrying Amount	68,751,000		68,751,000		75,650,000
Patents and Licensed Technology [Member]
Amortizable intangible assets components
Gross Carrying Amount	452,161,000		452,161,000		407,002,000
Accumulated Amortization	(198,392,000)		(198,392,000)		(170,320,000)
Net Carrying Amount	$ 253,769,000		$ 253,769,000		$ 236,682,000