Intangible Assets (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 26, 2014	Oct. 27, 2013	Oct. 26, 2014	Oct. 27, 2013	Oct. 26, 2014 Acquisition-related intangible assets	Jan. 26, 2014 Acquisition-related intangible assets	Oct. 26, 2014 Patents and Licensed Technology	Jan. 26, 2014 Patents and Licensed Technology	Oct. 26, 2014 Total intangible assets	Jan. 26, 2014 Total intangible assets
Amortizable intangible assets components
Gross Carrying Amount					$ 189,239,000	$ 189,239,000	$ 449,204,000	$ 446,196,000	$ 638,443,000	$ 635,435,000
Accumulated Amortization					(129,073,000)	(114,104,000)	(268,069,000)	(225,319,000)	(397,142,000)	(339,423,000)
Net Carrying Amount					60,166,000	75,135,000	181,135,000	220,877,000	241,301,000	296,012,000
Future amortization expense associated with intangible assets
Remainder of fiscal 2015	19,300,000		19,300,000
Fiscal 2016	71,900,000		71,900,000
Fiscal 2017	63,800,000		63,800,000
Fiscal 2018	49,100,000		49,100,000
Fiscal 2019	20,500,000		20,500,000
Fiscal 2020 and beyond	16,700,000		16,700,000
Amortization expense	$ 19,300,000	$ 19,600,000	$ 57,700,000	$ 55,600,000