CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
NET REVENUES		$ 88,878	$ 90,144	$ 256,700	$ 262,202
COST OF REVENUES		44,717	41,092	126,229	118,437
GROSS PROFIT		44,161	49,052	130,471	143,765
OPERATING EXPENSES:
Research and development		13,888	13,458	43,693	41,314
Sales and marketing		11,129	11,564	35,701	35,906
General and administrative		7,361	7,155	23,133	22,614
Total operating expenses		32,378	32,177	102,527	99,834
INCOME FROM OPERATIONS		11,783	16,875	27,944	43,931
OTHER INCOME
Other income, net		428	381	219	836
Total other income		428	381	219	836
INCOME BEFORE INCOME TAXES		12,211	17,256	28,163	44,767
PROVISION FOR (BENEFIT FROM) INCOME TAXES		698	1,145	1,717	(423)
NET INCOME		$ 11,513	$ 16,111	$ 26,446	$ 45,190
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.40	$ 0.54	$ 0.91	$ 1.50
Diluted (in dollars per share)	[1]	$ 0.39	$ 0.52	$ 0.89	$ 1.46
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		28,855	30,013	29,175	30,186
Diluted (in shares)		29,298	30,757	29,856	31,053

[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 excluded the shares underlying the 2015 and 2014 awards in the 2015 and 2014 calculations, respectively, as those shares were not contingently issuable as of the end of the period.