Significant Accounting Policies - Deferred Revenue (Details) (USD $) In Thousands, unless otherwise specified	Jan. 25, 2015	Jan. 26, 2014
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 5,848	$ 7,267
Deferred Revenues [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	6,237	7,179
Deferred Cost of Revenues [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	(1,562)	(1,698)
Deferred Gross Profit [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	4,675	5,481
Deferred Product Design and Engineering Recoveries [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 1,173	$ 1,786