Consolidated Condensed Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 29, 2012	Jul. 31, 2011	Jul. 29, 2012	Jul. 31, 2011
Income Statement [Abstract]
Net sales	$ 150,704	$ 130,254	$ 267,346	$ 252,625
Cost of sales	76,179	51,534	137,484	100,051
Gross profit	74,525	78,720	129,862	152,574
Operating costs and expenses:
Selling, general and administrative	31,220	22,481	76,038	49,186
Product development and engineering	32,613	22,228	56,696	40,753
Intangible amortization and impairments	7,977	2,103	13,555	4,205
Total operating costs and expenses	71,810	46,812	146,289	94,144
Operating income (loss)	2,715	31,908	(16,427)	58,430
Interest expense	(3,442)	0	(4,955)	0
Interest income and other (expense), net	(590)	(117)	(706)	(557)
(Loss) income before taxes	(1,317)	31,791	(22,088)	57,873
(Benefit) provision for taxes	(11,339)	4,653	(34,319)	8,153
Net income	$ 10,022	$ 27,138	$ 12,231	$ 49,720
Earnings per share:
Basic	$ 0.15	$ 0.41	$ 0.19	$ 0.76
Diluted	$ 0.15	$ 0.40	$ 0.18	$ 0.74
Weighted average number of shares used in computing earnings per share:
Basic	65,587	65,547	65,435	65,050
Diluted	67,165	68,186	67,207	67,638