CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
NET REVENUES		$ 102,865	$ 109,482	$ 192,053	$ 212,563
COST OF REVENUES		51,293	53,248	95,007	102,785
GROSS PROFIT		51,572	56,234	97,046	109,778
OPERATING EXPENSES:
Research and development		19,269	17,898	37,215	35,379
Sales and marketing		13,209	13,497	26,226	26,585
General and administrative		9,334	9,220	17,724	18,234
Total operating expenses		41,812	40,615	81,165	80,198
INCOME FROM OPERATIONS		9,760	15,619	15,881	29,580
OTHER INCOME		1,310	885	2,462	1,721
INCOME BEFORE INCOME TAXES		11,070	16,504	18,343	31,301
PROVISION FOR INCOME TAXES		225	1,123	265	1,720
NET INCOME		$ 10,845	$ 15,381	$ 18,078	$ 29,581
EARNINGS PER SHARE:
Basic (in dollars per share)		$ 0.37	$ 0.52	$ 0.62	$ 1.00
Diluted (in dollars per share)	[1]	$ 0.37	$ 0.51	$ 0.61	$ 0.97
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		29,297	29,505	29,125	29,651
Diluted (in shares)		29,702	30,183	29,597	30,387

[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.