Segment Information - Net Sales Activity by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Revenue from External Customer [Line Items]
Net sales	$ 137,185	$ 115,810	$ 404,241	$ 371,610
Semiconductor Products Group [Member]
Revenue from External Customer [Line Items]
Net sales	137,185	115,795	404,036	369,690
All others [Member]
Revenue from External Customer [Line Items]
Net sales	$ 0	$ 15	$ 205	$ 1,920