CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
NET REVENUES		$ 420,669	$ 415,955	$ 431,755
COST OF REVENUES		207,267	201,167	218,091
GROSS PROFIT		213,402	214,788	213,664
OPERATING EXPENSES:
Research and development		73,470	70,580	68,501
Sales and marketing		54,297	53,064	51,384
General and administrative		37,582	35,496	36,142
Litigation settlement		(168,969)	0	0
Total operating expenses		(3,620)	159,140	156,027
INCOME FROM OPERATIONS		217,022	55,648	57,637
OTHER INCOME		5,392	4,116	2,662
INCOME BEFORE INCOME TAXES		222,414	59,764	60,299
PROVISION (BENEFIT) FOR INCOME TAXES		28,946	(10,220)	32,690
NET INCOME		$ 193,468	$ 69,984	$ 27,609
EARNINGS PER SHARE:
Basic		$ 6.61	$ 2.38	$ 0.93
Diluted	[1]	$ 6.49	$ 2.32	$ 0.90
SHARES USED IN PER SHARE CALCULATION:
Basic		29,267	29,456	29,674
Diluted	[1]	29,816	30,147	30,545

[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 included in the 2019, 2018 and 2017 calculations those shares that were contingently issuable upon the satisfaction of the performance conditions as of the end of the respective periods.