Segment Information - Net Sales Activity by Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 29, 2017	Oct. 30, 2016	Oct. 29, 2017	Oct. 30, 2016
Revenue from External Customer [Line Items]
Net sales	$ 150,304	$ 137,185	$ 447,233	$ 404,241
Semiconductor Products Group [Member]
Revenue from External Customer [Line Items]
Net sales	150,304	137,185	447,233	404,036
All others [Member]
Revenue from External Customer [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 205

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration