Concentration of Risk - Narrative (Details)	3 Months Ended
	Apr. 26, 2015	Apr. 27, 2014
Net sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%
Net sales [Member] | Distributor concentration risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	57.00%	53.00%
China | Cost of Silicon Wafers [Member] | Supplier concentration risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	30.00%	54.00%