Goodwill and Intangible Assets - Future Amortization Expense For Intangible Assets (Details) - USD ($) $ in Thousands		Jul. 26, 2015	Jan. 25, 2015
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining six months of fiscal year 2016		$ 12,547
Fiscal year 2017		25,083
Fiscal year 2018		25,041
Fiscal year 2019		21,629
Fiscal year 2020		10,348
Thereafter		2,518
Net carrying amount		97,166	$ 97,600
Core Technologies [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining six months of fiscal year 2016		10,322
Fiscal year 2017		20,641
Fiscal year 2018		20,641
Fiscal year 2019		17,229
Fiscal year 2020		9,398
Thereafter		2,485
Net carrying amount		80,716	80,869
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining six months of fiscal year 2016		2,200
Fiscal year 2017		4,400
Fiscal year 2018		4,400
Fiscal year 2019		4,400
Fiscal year 2020		950
Thereafter		33
Net carrying amount		16,383	16,550
Technology Licenses [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining six months of fiscal year 2016		25
Fiscal year 2017		42
Fiscal year 2018		0
Fiscal year 2019		0
Fiscal year 2020		0
Thereafter		0
Net carrying amount	[1]	$ 67	$ 94

[1] Technology licenses relate to end-license agreements for intellectual property that is used by the Company in research and development activities and also has alternative future uses. Amortization expense related to technology licenses is reported as “Product development and engineering” in the condensed consolidated statements of operations.