Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jan. 27, 2013	Jan. 29, 2012
Components of Deferred Tax Assets and Liabilities [Abstract]
Total current deferred tax liability	$ (4,221)	$ (4,041)
Net deferred tax asset	34,773	298
Current Deferred Tax Asset [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred revenue	1,889	2,346
Inventory reserve	567	347
Payroll and related accruals	2,444	1,926
Bad debt reserve	323	359
Accrued service fees	626	405
Other deferred assets	2,593	508
Valuation allowance	(969)	(552)
Total current deferred tax asset	7,473	5,339
Noncurrent Deferred Tax Asset [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Payroll and related accruals	5,389	4,497
Other deferred assets	3,395	772
Research and development charges	2,900	3,708
Research credit carryforward	49,257	11,967
Acquired NOL carryforward	28,595	16,489
Stock-based compensation	8,456	10,248
Valuation allowance	(7,351)	(5,065)
Total non-current deferred tax asset	90,641	42,616
Current Deferred Tax Liability [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Inventory reserve - foreign	(1,618)	(2,115)
Bad debt reserve - foreign	(773)	(671)
Depreciation - foreign	(1,744)	(1,074)
Other deferred tax liability	(86)	(181)
Total current deferred tax liability	(4,221)	(4,041)
Noncurrent Deferred Tax Liability [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Other deferred tax liability	(1,435)	(254)
Domestic tax on foreign earnings	0	(23,443)
Purchase accounting deferred tax liability	(49,181)	(14,159)
Depreciation and amortization	(8,504)	(5,760)
Total non-current deferred tax liability	$ (59,120)	$ (43,616)