CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
NET REVENUES		$ 111,255	$ 101,625	$ 323,506	$ 287,232
COST OF REVENUES		55,542	51,783	163,870	145,117
GROSS PROFIT		55,713	49,842	159,636	142,115
OPERATING EXPENSES:
Research and development		17,340	15,906	51,321	46,544
Sales and marketing		12,768	12,029	38,128	35,453
General and administrative		9,546	8,789	27,015	24,772
Total operating expenses		39,654	36,724	116,464	106,769
INCOME FROM OPERATIONS		16,059	13,118	43,172	35,346
OTHER INCOME		895	282	1,866	779
INCOME BEFORE INCOME TAXES		16,954	13,400	45,038	36,125
PROVISION FOR INCOME TAXES		448	591	531	1,530
NET INCOME		$ 16,506	$ 12,809	$ 44,507	$ 34,595
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.55	$ 0.44	$ 1.50	$ 1.20
Diluted (in dollars per share)	[1]	$ 0.54	$ 0.43	$ 1.46	$ 1.17
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		29,759	28,972	29,646	28,834
Diluted (in shares)		30,614	29,625	30,472	29,480

[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.