Selected Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 27, 2013	Oct. 28, 2012	Jul. 29, 2012	Apr. 29, 2012	Jan. 29, 2012	Oct. 30, 2011	Jul. 31, 2011	May 01, 2011	Jan. 27, 2013	Jan. 29, 2012	Jan. 30, 2011
Selected Quarterly Financial Data (in Dollars) [Abstract]
Net sales	$ 150,603	$ 160,878	$ 150,704	$ 116,642	$ 104,032	$ 123,944	$ 130,254	$ 122,371	$ 578,827	$ 480,601	$ 454,502
Cost of sales	62,646	64,085	76,179	61,305	44,368	50,537	51,534	48,517	264,215	194,956	186,196
Gross profit	87,957	96,793	74,525	55,337	59,664	73,407	78,720	73,854	314,612	285,645	268,306
Operating costs and expenses:
Selling, general and administrative	37,386	35,646	31,220	44,818	26,333	25,110	22,481	26,705	149,070	100,629	110,404
Product development and engineering	29,959	33,354	32,613	24,083	19,335	20,489	22,228	18,525	120,009	80,577	69,624
Intangible amortization and impairments	8,177	8,212	7,977	5,578	2,075	4,573	2,103	2,102	29,944	10,853	9,520
Total operating costs and expenses	75,522	77,212	71,810	74,479	47,743	50,172	46,812	47,332	299,023	192,059	189,548
Operating (loss) income	12,435	19,581	2,715	(19,142)	11,921	23,235	31,908	26,522	15,589	93,586	78,758
Interest expense	(4,154)	(4,172)	(4,194)	(1,843)	0	0	0	0	(14,363)	0	0
Interest income and other (expense) income, net	(282)	(1,071)	162	214	421	729	(117)	(440)	(977)	593	574
Income before taxes	7,999	14,338	(1,317)	(20,771)	12,342	23,964	31,791	26,082	249	94,179	79,332
(Benefit) provision for taxes	(5,119)	(2,252)	(11,339)	(22,980)	(46)	(3,015)	4,653	3,500	(41,690)	5,092	6,760
Net income	$ 13,118	$ 16,590	$ 10,022	$ 2,209	$ 12,388	$ 26,979	$ 27,138	$ 22,582	$ 41,939	$ 89,087	$ 72,572
Basic (in dollars per share)	$ 0.20	$ 0.25	$ 0.15	$ 0.03	$ 0.19	$ 0.41	$ 0.41	$ 0.35	$ 0.64	$ 1.37	$ 1.16
Diluted (in dollars per share)	$ 0.19	$ 0.25	$ 0.15	$ 0.03	$ 0.19	$ 0.40	$ 0.40	$ 0.34	$ 0.62	$ 1.32	$ 1.12
Weighted average number of shares used in computing earnings per share:
Basic (in shares)	66,371	65,996	65,587	65,282	64,856	65,440	65,547	64,552	65,809	65,099	62,339
Diluted (in shares)	67,984	67,465	67,165	67,233	66,776	67,314	68,186	67,123	67,472	67,350	64,523
Selected Quarterly Financial Data (as a Percent of Revenue) [Abstract]
Net sales	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%
Cost of sales	42.00%	40.00%	50.00%	53.00%	43.00%	41.00%	40.00%	40.00%
Gross profit	58.00%	60.00%	50.00%	47.00%	57.00%	59.00%	60.00%	60.00%
Operating Costs and Expenses [Abstract]
Selling, general and administrative	25.00%	22.00%	21.00%	38.00%	25.00%	20.00%	17.00%	22.00%
Product development and engineering	20.00%	21.00%	22.00%	21.00%	19.00%	17.00%	17.00%	15.00%
Intangible amortization and impairments	5.00%	5.00%	5.00%	5.00%	2.00%	4.00%	2.00%	2.00%
Total operating costs and expenses	50.00%	48.00%	48.00%	64.00%	46.00%	41.00%	36.00%	39.00%
Operating (loss) income	8.00%	12.00%	2.00%	(17.00%)	11.00%	19.00%	24.00%	22.00%
Interest expense	(3.00%)	(3.00%)	(3.00%)	(2.00%)	0.00%	0.00%	0.00%	0.00%
Interest income and other (expense) income, net	0.00%	(1.00%)	0.00%	0.00%	0.00%	1.00%	0.00%	0.00%
(Loss) income before taxes	5.00%	8.00%	(1.00%)	(19.00%)	11.00%	20.00%	24.00%	22.00%
(Benefit) provision for taxes	(3.00%)	(1.00%)	(8.00%)	(20.00%)	0.00%	(2.00%)	4.00%	3.00%
Net Income	8.00%	9.00%	7.00%	1.00%	11.00%	22.00%	20.00%	19.00%