CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
NET REVENUES		$ 85,265	$ 88,985	$ 167,822	$ 172,058
COST OF REVENUES		41,247	40,249	81,512	77,345
GROSS PROFIT		44,018	48,736	86,310	94,713
OPERATING EXPENSES:
Research and development		14,864	14,366	29,805	27,856
Sales and marketing		12,459	12,232	24,572	24,342
General and administrative		7,491	7,813	15,772	15,459
Total operating expenses		34,814	34,411	70,149	67,657
INCOME FROM OPERATIONS		9,204	14,325	16,161	27,056
OTHER INCOME (EXPENSE)
Other income (expense), net		14	198	(209)	455
Total other income (expense)		14	198	(209)	455
INCOME BEFORE INCOME TAXES		9,218	14,523	15,952	27,511
PROVISION FOR (BENEFIT FROM) INCOME TAXES		628	(2,193)	1,019	(1,568)
NET INCOME		$ 8,590	$ 16,716	$ 14,933	$ 29,079
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.29	$ 0.55	$ 0.51	$ 0.96
Diluted (in dollars per share)	[1]	$ 0.29	$ 0.54	$ 0.50	$ 0.93
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		29,368	30,310	29,339	30,275
Diluted (in shares)	[1]	30,034	31,110	30,075	31,150

[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.