QUARTERLY RESULTS (UNAUDITED) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 185,304,000		$ 164,965,000		$ 161,344,000		$ 166,323,000		$ 195,347,000		$ 165,059,000		$ 162,160,000		$ 155,956,000		$ 677,936,000	$ 678,522,000	$ 628,970,000
Cost of revenues	84,358,000		76,545,000		78,276,000		79,038,000		89,575,000		78,615,000		78,976,000		77,309,000		320,910,000	327,774,000	305,948,000
Amortization of intangible assets	657,000		685,000		685,000		666,000		642,000		745,000		946,000		966,000		2,693,000	3,299,000	2,033,000
Gross profit	100,289,000		87,735,000		82,383,000		86,619,000		105,130,000		85,699,000		82,238,000		77,681,000		357,026,000	350,748,000	323,022,000
Restructuring costs																	0	0	799,000
Operating expenses [Abstract]
Research & development	28,722,000		28,960,000		30,453,000		29,973,000		30,881,000		28,929,000		30,268,000		30,151,000		118,108,000	120,229,000	120,989,000
Marketing and selling	47,592,000		45,411,000		46,052,000		44,810,000		47,759,000		43,199,000		44,474,000		41,746,000		183,865,000	177,178,000	173,601,000
General and administrative	14,393,000	[1]	13,240,000	[1]	14,920,000	[1]	15,298,000	[1]	16,166,000	[1]	19,698,000	[1]	13,879,000	[1]	14,602,000	[1]	57,851,000	64,345,000	61,087,000
Amortization of intangible assets	2,063,000		2,159,000		2,161,000		2,145,000		2,186,000		2,283,000		2,417,000		2,857,000		8,528,000	9,743,000	10,511,000
Restructuring and other costs, net	8,530,000		2,707,000		(163,000)		(2,216,000)		14,918,000		185,000		4,007,000		1,340,000		8,858,000	20,450,000	26,873,000
Loss (gain) on sales of assets	0		0		597,000		0		(3,502,000)		(1,527,000)		0		0		597,000	(5,029,000)	(155,000)
Total operating expenses	101,300,000		92,477,000		94,020,000		90,010,000		108,408,000		92,767,000		95,045,000		90,696,000		377,807,000	386,916,000	392,906,000
Operating loss	(1,011,000)		(4,742,000)		(11,637,000)		(3,391,000)		(3,278,000)		(7,068,000)		(12,807,000)		(13,015,000)		(20,781,000)	(36,168,000)	(69,884,000)
Other income (expense), net	(497,000)		(503,000)		(768,000)		(300,000)		(258,000)		(30,000)		(102,000)		0		(159,000)	301,000	(65,000)
Loss before income taxes	(1,508,000)		(5,245,000)		(12,405,000)		(3,691,000)		(3,536,000)		(7,098,000)		(12,909,000)		(13,015,000)		(22,849,000)	(36,558,000)	(70,007,000)
Provision for (benefit from) income taxes, net	(2,715,000)	[2]	2,774,000	[2]	(543,000)	[2]	1,426,000	[2]	(2,965,000)	[2]	2,897,000	[2]	(3,000)	[2]	467,000	[2]	942,000	396,000	(1,652,000)
Net loss	1,207,000		(8,019,000)		(11,862,000)		(5,117,000)		(571,000)		(9,995,000)		(12,906,000)		(13,482,000)		(23,791,000)	(36,954,000)	(68,355,000)
Net Income (Loss) Per Share, Basic	$ 0.03		$ (0.21)		$ (0.31)		$ (0.13)		$ (0.01)		$ (0.26)		$ (0.34)		$ (0.36)
Net Income (Loss) Per Share, Diluted	$ 0.03		$ (0.21)		$ (0.31)		$ (0.13)		$ (0.01)		$ (0.26)		$ (0.34)		$ (0.36)
Weighted Average Number of Shares Outstanding, Basic (in shares)	38,580		38,511		38,413		38,228		38,101		38,045		37,909		37,516
Weighted Average Number of Shares Outstanding, Diluted (in shares)	38,584		38,511		38,413		38,228		38,101		38,045		37,909		37,516
High common stock price (in dollars per share)	$ 9.05		$ 20.38		$ 22.95		$ 23.35		$ 18.83		$ 13.82		$ 17.99		$ 14.84
Low common stock price (in dollars per share)	$ 5.76		$ 7.72		$ 16.15		$ 16.32		$ 12.23		$ 11.04		$ 12.26		$ 12.26
General and Administrative Legal Settlement Expenses											$ 5,600,000

[1] General and administrative expenses for the quarter ended September 30, 2010 included costs of $5.6 million related to a legal settlement recorded in that period.

[2] See Note P, “Income Taxes.”