CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
NET REVENUES		$ 114,159	$ 110,085	$ 306,212	$ 322,648
COST OF REVENUES		56,028	53,080	151,035	155,865
GROSS PROFIT		58,131	57,005	155,177	166,783
OPERATING EXPENSES:
Research and development		17,957	17,236	55,172	52,615
Sales and marketing		13,452	13,278	39,678	39,863
General and administrative		9,224	8,466	26,948	26,700
Total operating expenses		40,633	38,980	121,798	119,178
INCOME FROM OPERATIONS		17,498	18,025	33,379	47,605
OTHER INCOME		1,078	1,098	3,540	2,819
INCOME BEFORE INCOME TAXES		18,576	19,123	36,919	50,424
PROVISION FOR INCOME TAXES		1,477	1,456	1,742	3,176
NET INCOME		$ 17,099	$ 17,667	$ 35,177	$ 47,248
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.58	$ 0.60	$ 1.20	$ 1.60
Diluted (in dollars per share)	[1]	$ 0.57	$ 0.59	$ 1.18	$ 1.56
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		29,385	29,365	29,213	29,558
Diluted (in shares)		29,866	29,998	29,709	30,281

[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 2019 and 2018 calculations as the shares were not contingently issuable as of the end of the reporting periods.