Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 25, 2015
Components of Deferred Tax Assets and Liabilities [Abstract]
Total current deferred tax liabilities	$ 0	$ (1,444)
Net deferred tax assets	552
Net deferred tax assets (liabilities)		(1,337)
Current Deferred Tax Asset [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred revenue	0	3,052
Inventory reserve	0	3,156
Payroll and related accruals	0	2,306
Bad debt reserve	0	927
Accrued service fees	0	608
Other deferred assets	0	1,191
Valuation allowance	0	(8,637)
Total current deferred tax asset	0	2,603
Noncurrent Deferred Tax Asset [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred revenue	4,295	0
Inventory reserve	2,931	0
Payroll and related accruals	8,773	7,148
Bad debt reserve	521	0
Other deferred assets	6,281	5,054
Accrued service fees	238	0
Research and development charges	584	1,323
Research credit carryforward	32,605	40,819
NOL carryforward	38,979	29,144
Stock-based compensation	5,006	6,176
Valuation allowance	(77,383)	(66,899)
Total non-current deferred tax asset	22,830	22,765
Current Deferred Tax Liability [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Inventory reserve - foreign	0	(826)
Bad debt reserve - foreign	0	(256)
Other deferred tax liabilities	0	(373)
Total current deferred tax liabilities	0	(1,455)
Noncurrent Deferred Tax Liability [Member]
Components of Deferred Tax Assets and Liabilities [Abstract]
Inventory reserve - foreign	(515)	0
Depreciation and amortization - foreign	(194)	0
Other deferred tax liabilities	(1,350)	(1,377)
Purchase accounting deferred tax liabilities	(16,895)	(20,917)
Depreciation and amortization	(3,324)	(2,956)
Total non-current deferred tax liabilities	$ (22,278)	$ (25,250)