CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Income Statement [Abstract]
NET REVENUES	$ 88,985		$ 87,922		$ 172,058		$ 164,962
COST OF REVENUES	40,249		41,715		77,345		78,891
GROSS PROFIT	48,736		46,207		94,713		86,071
OPERATING EXPENSES:
Research and development	14,366		13,489		27,856		25,761
Sales and marketing	12,232		11,364		24,342		22,145
General and administrative	7,813		8,066		15,459		15,800
Total operating expenses	34,411		32,919		67,657		63,706
INCOME FROM OPERATIONS	14,325		13,288		27,056		22,365
OTHER INCOME
Other income, net	198		565		455		782
Total other income	198		565		455		782
INCOME BEFORE PROVISION FOR (BENEFIT FROM) INCOME TAXES	14,523		13,853		27,511		23,147
PROVISION FOR (BENEFIT FROM) INCOME TAXES	(2,193)		181		(1,568)		(1,428)
NET INCOME	$ 16,716		$ 13,672		$ 29,079		$ 24,575
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.55		$ 0.47		$ 0.96		$ 0.85
Diluted (in dollars per share)	$ 0.54	[1]	$ 0.45	[1]	$ 0.93	[1]	$ 0.82	[1]
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)	30,310		29,178		30,275		28,967
Diluted (in shares)	31,110	[1]	30,158	[1]	31,150	[1]	29,977	[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 excluded the shares underlying the 2014 and 2013 awards in the 2014 and 2013 calculations, respectively, as those shares were not contingently issuable as of the end of the period.