Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 25, 2015
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 8,628	$ 5,848
Deferred Revenues [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	5,991	6,237
Deferred Cost of Revenues [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	(1,139)	(1,562)
Deferred Revenue, Net [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	4,852	4,675
Deferred Product Design and Engineering Recoveries [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 3,776	$ 1,173