Quarterly Results Of Operations (Schedule Of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Dec. 31, 2010	Oct. 02, 2010	Jul. 03, 2010	Apr. 03, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Results Of Operations [Abstract]
Net sales of tangible products	$ 235,714	$ 241,686	$ 232,762	$ 226,120	$ 222,048	$ 218,271	$ 207,748	$ 201,463	$ 936,282	$ 849,530	$ 696,103
Revenue from services and software	11,594	11,652	12,779	11,181	11,971	11,536	10,810	10,512	47,206	44,829	42,379
Total net sales	247,308	253,338	245,541	237,301	234,019	229,807	218,558	211,975	983,488	894,359	738,482
Cost of sales of tangible products	118,792	122,529	117,732	110,781	112,550	114,924	114,081	109,075	469,834	450,630	398,316
Cost of services and software	6,996	7,256	6,111	6,522	7,113	5,636	5,068	5,137	26,885	22,954	22,579
Cost of sales	125,788	129,785	123,843	117,303	119,663	120,560	119,149	114,212	496,719	473,584	420,895
Gross Profit	121,520	123,553	121,698	119,998	114,356	109,247	99,409	97,763	486,769	420,775	317,587
Selling and marketing	36,377	31,942	30,950	28,528	31,942	28,068	27,682	24,673	127,797	112,365	92,043
Research and development	23,174	22,584	22,487	21,681	21,736	21,862	20,653	18,324	89,926	82,575	66,477
General and administrative	19,089	19,166	20,688	22,706	17,809	18,147	17,955	19,318	81,649	73,229	75,932
Amortization of intangible assets	806	843	836	835	891	839	740	741	3,320	3,211	2,954
Litigation settlement	0	0	0	0	(1,082)	0	0	0	0	(1,082)	0
Exit and restructuring costs	(49)	138	66	1,886	30	0	466	1,766	2,041	2,262	9,902
Total operating expenses	79,397	74,673	75,027	75,636	71,326	68,916	67,496	64,822	304,733	272,560	247,308
Operating income	42,123	48,880	46,671	44,362	43,030	40,331	31,913	32,941	182,036	148,215	70,279
Investment income (loss)	594	134	656	560	567	635	634	842	1,944	2,678	2,931
Foreign exchange gain (loss)	(706)	(173)	(833)	(294)	(613)	(148)	424	168	(2,006)	(169)	(104)
Other, net	(899)	(859)	(243)	(254)	(232)	(160)	(455)	(270)	(2,255)	(1,117)	(787)
Total other income (loss)	(1,011)	(898)	(420)	12	(278)	327	603	740	(2,317)	1,392	2,040
Income from continuing operations before income taxes	41,112	47,982	46,251	44,374	42,752	40,658	32,516	33,681	179,719	149,607	72,319
Income taxes	8,253	13,795	13,082	14,246	13,117	13,411	10,331	8,134	49,376	44,993	23,828
Income from continuing operations	32,859	34,187	33,169	30,128	29,635	27,247	22,185	25,547	130,343	104,614	48,491
Income (loss) from discontinued operations, net of tax	2,185	10,814	(205)	31,506	(1,418)	(1,096)	492	(814)	44,300	(2,836)	(1,387)
Net income	$ 35,044	$ 45,001	$ 32,964	$ 61,634	$ 28,217	$ 26,151	$ 22,677	$ 24,733	$ 174,643	$ 101,778	$ 47,104
Income from continuing operations, Basic per share	$ 0.63	$ 0.64	$ 0.60	$ 0.54	$ 0.53	$ 0.48	$ 0.38	$ 0.44	$ 2.42	$ 1.83	$ 0.81
Income (loss) from discontinued operations, Basic per share	$ 0.04	$ 0.20	$ 0.00	$ 0.57	$ (0.03)	$ (0.02)	$ 0.01	$ (0.01)	$ 0.82	$ (0.05)	$ (0.02)
Net Income	$ 0.67	$ 0.84	$ 0.60	$ 1.11	$ 0.50	$ 0.46	$ 0.39	$ 0.43	$ 3.24	$ 1.78	$ 0.79
Income from continuing operations	$ 0.63	$ 0.64	$ 0.60	$ 0.54	$ 0.53	$ 0.48	$ 0.38	$ 0.44	$ 2.40	$ 1.82	$ 0.81
Income from discontinued operations	$ 0.04	$ 0.20	$ 0.00	$ 0.56	$ (0.03)	$ (0.02)	$ 0.01	$ (0.02)	$ 0.82	$ (0.05)	$ (0.02)
Net Income	$ 0.67	$ 0.84	$ 0.60	$ 1.10	$ 0.50	$ 0.46	$ 0.39	$ 0.42	$ 3.22	$ 1.77	$ 0.79
Basic weighted average shares outstanding	52,108	53,339	54,546	55,353	56,332	56,739	57,489	58,016	53,854	57,143	59,306
Diluted weighted average and equivalent shares outstanding	52,354	53,628	54,958	55,774	56,692	56,998	57,737	58,265	54,191	57,428	59,425