CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
NET REVENUES		$ 107,563	$ 97,571	$ 212,251	$ 185,607
COST OF REVENUES		54,116	49,786	108,328	93,334
GROSS PROFIT		53,447	47,785	103,923	92,273
OPERATING EXPENSES:
Research and development		17,341	15,859	33,981	30,638
Sales and marketing		13,144	12,018	25,360	23,424
General and administrative		8,765	8,133	17,469	15,983
Total operating expenses		39,250	36,010	76,810	70,045
INCOME FROM OPERATIONS		14,197	11,775	27,113	22,228
OTHER INCOME		465	236	971	497
INCOME BEFORE INCOME TAXES		14,662	12,011	28,084	22,725
PROVISION FOR INCOME TAXES		760	604	83	939
NET INCOME		$ 13,902	$ 11,407	$ 28,001	$ 21,786
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.47	$ 0.40	$ 0.95	$ 0.76
Diluted (in dollars per share)	[1]	$ 0.46	$ 0.39	$ 0.92	$ 0.74
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		29,720	28,850	29,589	28,765
Diluted (in shares)		30,454	29,422	30,370	29,361

[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 outstanding performance-based awards in the 2017 and 2016 calculations as the shares were not contingently issuable as of the end of the reporting periods.