Concentration of Risk - Narrative (Details)	3 Months Ended
	Apr. 30, 2017	May 01, 2016
Concentration Risk [Line Items]
Description of geographic concentration risk related to distributors	For the third quarter of fiscal year 2017, our two largest distributors were based in Asia.
Sales Revenue, Goods, Net [Member]
Concentration Risk [Line Items]
Minimum concentration risk threshold	10.00%
Concentration risk, percentage	100.00%	100.00%
Accounts Receivable [Member]
Concentration Risk [Line Items]
Minimum concentration risk threshold	10.00%
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	64.00%	65.00%
China | Cost of Silicon Wafers [Member] | Supplier concentration risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%	25.00%