Intangible Assets (Details) (USD $)	12 Months Ended
	Jan. 25, 2015	Jan. 26, 2014	Jan. 27, 2013
Amortizable intangible assets components [Line Items]
Gross Carrying Amount	$ 638,112,000	$ 635,435,000
Accumulated Amortization	(416,398,000)	(339,423,000)
Net Carrying Amount	221,714,000	296,012,000
Amortization expense associated with intangible assets
Amortization expense	77,000,000	72,700,000	68,400,000
Future amortization expense associated with intangible assets
Fiscal 2016	71,900,000
Fiscal 2017	63,600,000
Fiscal 2018	49,100,000
Fiscal 2019	20,400,000
Fiscal 2020	11,900,000
Future amortization after year five	4,800,000
Acquisition-related intangible assets
Amortizable intangible assets components [Line Items]
Gross Carrying Amount	189,239,000	189,239,000
Accumulated Amortization	(134,062,000)	(114,104,000)
Net Carrying Amount	55,177,000	75,135,000
Finite-Lived Intangible Assets, Average Useful Life	6 years 9 months 17 days	6 years 6 months 0 days
Patents and Licensed Technology [Member]
Amortizable intangible assets components [Line Items]
Gross Carrying Amount	448,873,000	446,196,000
Accumulated Amortization	(282,336,000)	(225,319,000)
Net Carrying Amount	$ 166,537,000	$ 220,877,000
Finite-Lived Intangible Assets, Average Useful Life	7 years 2 months 12 days	7 years 2 months 12 days