Segment Information - Net Sales Activity by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 28, 2018	Oct. 29, 2017	Jul. 30, 2017	Apr. 30, 2017	Jan. 29, 2017	Oct. 30, 2016	Jul. 31, 2016	May 01, 2016	Jan. 28, 2018	Jan. 29, 2017	Jan. 31, 2016
Revenue from External Customer [Line Items]
Net sales	$ 140,614	$ 150,304	$ 153,127	$ 143,802	$ 140,031	$ 137,185	$ 135,911	$ 131,145	$ 587,847	$ 544,272	$ 490,219
Semiconductor Products Group [Member]
Revenue from External Customer [Line Items]
Net sales									587,847	544,067	485,570
All Other Segments [Member]
Revenue from External Customer [Line Items]
Net sales									$ 0	$ 205	$ 4,649