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. 26, 2014	Oct. 27, 2013	Jul. 28, 2013	Apr. 28, 2013	Jan. 27, 2013	Oct. 28, 2012	Jul. 29, 2012	Apr. 29, 2012	Jan. 26, 2014	Jan. 27, 2013	Jan. 29, 2012
Selected Quarterly Financial Data (in Dollars) [Abstract]
Net sales	$ 126,534	$ 141,026	$ 165,010	$ 162,407	$ 150,603	$ 160,878	$ 150,704	$ 116,642	$ 594,977	$ 578,827	$ 480,601
Cost of sales	57,682	57,615	64,302	65,120	62,646	64,085	76,179	61,305	244,719	264,215	194,956
Cost of sales - lower of cost or market write-down	15,047	0	0	0	0	0	0	0	15,047	0	0
Operating costs and expenses:
Selling, general and administrative	26,421	30,849	33,315	34,794	37,386	35,646	31,220	44,818	125,379	149,070	100,629
Product development and engineering	37,805	31,948	33,125	34,559	29,959	33,354	32,613	24,083	137,437	120,009	80,577
Intangible amortization	6,586	7,349	7,211	7,856	8,177	8,212	7,977	4,878	29,002	29,244	8,383
Intangible asset impairments	29,938	0	2,600	0	0	0	0	700	32,538	700	2,470
Goodwill impairment	116,686	0	0	0	0	0	0	0	116,686	0	0
Restructuring	3,086	0	0	0	0	0	0	0	3,086	0	0
Total operating costs and expenses	220,522	70,146	76,251	77,209	75,522	77,212	71,810	74,479	444,128	299,023	192,059
Operating (loss) income	(166,717)	13,265	24,457	20,078	12,435	19,581	2,715	(19,142)	(108,917)	15,589	93,586
Interest expense	(1,712)	(1,818)	(10,584)	(4,060)	(4,154)	(4,172)	(4,194)	(1,843)	(18,174)	(14,363)	0
Interest income and other (expense) income, net	(126)	(259)	(198)	(807)	(282)	(1,071)	162	214	(1,390)	(977)	593
(Loss) income before taxes	(168,555)	11,188	13,675	15,211	7,999	14,338	(1,317)	(20,771)	(128,481)	249	94,179
Provision (benefit) for taxes	42,253	(1,265)	(5,437)	434	(5,119)	(2,252)	(11,339)	(22,980)	35,985	(41,690)	5,092
Net income (loss)	$ (210,808)	$ 12,453	$ 19,112	$ 14,777	$ 13,118	$ 16,590	$ 10,022	$ 2,209	$ (164,466)	$ 41,939	$ 89,087
Basic (in dollars per share)	$ (3.12)	$ 0.18	$ 0.28	$ 0.22	$ 0.20	$ 0.25	$ 0.15	$ 0.03	$ (2.44)	$ 0.64	$ 1.37
Diluted (in dollars per share)	$ (3.12)	$ 0.18	$ 0.28	$ 0.22	$ 0.19	$ 0.25	$ 0.15	$ 0.03	$ (2.44)	$ 0.62	$ 1.32
Weighted average number of shares used in computing earnings per share:
Basic (in shares)	67,523	67,792	67,614	66,956	66,371	65,996	65,587	65,282	67,471	65,809	65,099
Diluted (in shares)	67,523	68,871	69,090	68,579	67,984	67,465	67,165	67,233	67,471	67,472	67,350
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	46.00%	41.00%	39.00%	40.00%	42.00%	40.00%	50.00%	53.00%
Cost of sales - lower of cost or market write-down	12.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Gross profit	42.00%	59.00%	61.00%	60.00%	58.00%	60.00%	50.00%	47.00%
Operating Costs and Expenses [Abstract]
Selling, general and administrative	21.00%	22.00%	20.00%	21.00%	25.00%	22.00%	21.00%	38.00%
Product development and engineering	30.00%	23.00%	20.00%	21.00%	20.00%	21.00%	22.00%	21.00%
Intangible amortization	5.00%	5.00%	4.00%	5.00%	5.00%	5.00%	5.00%	4.00%
Intangible impairments	24.00%	0.00%	2.00%	0.00%	0.00%	0.00%	0.00%	1.00%
Goodwill impairment	92.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Restructuring charges	2.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Total operating costs and expenses	174.00%	50.00%	46.00%	47.00%	50.00%	48.00%	48.00%	64.00%
Operating (loss) income	(132.00%)	9.00%	15.00%	13.00%	8.00%	12.00%	2.00%	(17.00%)
Interest expense	(1.00%)	(1.00%)	(6.00%)	(2.00%)	(3.00%)	(3.00%)	(3.00%)	(2.00%)
Interest income and other (expense) income, net	0.00%	0.00%	0.00%	0.00%	0.00%	(1.00%)	0.00%	0.00%
(Loss) income before taxes	(133.00%)	8.00%	9.00%	11.00%	5.00%	8.00%	(1.00%)	(19.00%)
(Benefit) provision for taxes	33.00%	(1.00%)	(3.00%)	0.00%	(3.00%)	(1.00%)	(8.00%)	(20.00%)
Net Income (loss)	(166.00%)	9.00%	12.00%	11.00%	8.00%	9.00%	7.00%	1.00%