SELECTED QUARTERLY INFORMATION (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 90,412	$ 91,715	$ 87,922	$ 77,040	$ 79,170	$ 78,045	$ 76,382	$ 71,773
Gross Profit	48,391	48,774	46,207	39,864	39,403	38,751	37,755	34,592	183,236		150,502		140,646
Net income (loss)	$ 16,037	$ 16,654	$ 13,672	$ 10,903	$ 9,716	$ (44,406)	$ (7,176)	$ 7,461	$ 57,266		$ (34,404)		$ 34,291
Earnings per share
Basic (per share)	$ 0.54	$ 0.56	$ 0.47	$ 0.38	$ 0.34	$ (1.54)	$ (0.25)	$ 0.26	$ 1.95		$ (1.20)		$ 1.20
Diluted (per share)	$ 0.52	$ 0.54	$ 0.45	$ 0.37	$ 0.33	$ (1.54)	$ (0.25)	$ 0.25	$ 1.88	[1]	$ (1.20)	[1]	$ 1.14	[1]
Shares used in per share calculation
Basic (in shares)	29,974	29,762	29,178	28,754	28,785	28,908	28,619	28,227	29,421		28,636		28,609
Diluted (in shares)	30,924	30,652	30,158	29,783	29,436	28,908	28,619	29,435	30,420	[1]	28,636	[1]	29,964	[1]

[1] The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has included the shares underlying the 2013 and 2012 awards in the 2013 and 2012 calculations, respectively, as those shares were contingently issuable upon the satisfaction of the annual targets consisting of net revenue, non-GAAP operating earnings and achievement of strategic goals as of the end of the periods. The Company has excluded all performance-based awards underlying the 2011 awards in the 2011 calculation as the performance conditions for those awards were not met as of the end of the period.