CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
NET REVENUES		$ 387,393	$ 343,989	$ 348,797
COST OF REVENUES		196,232	170,602	159,227
GROSS PROFIT		191,161	173,387	189,570
OPERATING EXPENSES:
Research and development		62,310	57,549	54,981
Sales and marketing		47,978	46,816	47,796
General and administrative		33,029	30,029	30,997
Total operating expenses		143,317	134,394	133,774
INCOME FROM OPERATIONS		47,844	38,993	55,796
OTHER INCOME:
OTHER INCOME		1,078	425	1,018
INCOME BEFORE INCOME TAXES		48,922	39,418	56,814
PROVISION FOR (BENEFIT FROM) INCOME TAXES		1,032	271	(2,730)
NET INCOME		$ 47,890	$ 39,147	$ 59,544
EARNINGS PER SHARE:
Basic (per share)		$ 1.66	$ 1.35	$ 1.99
Diluted (per share)	[1]	$ 1.62	$ 1.32	$ 1.93
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)		28,925	29,001	29,976
Diluted (in shares)	[1]	29,619	29,696	30,829

[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 all performance-based awards in the 2014 calculation as the performance conditions for those awards were not met as of the end of the period. The Company has included in the 2016 and 2015 calculations those shares that were contingently issuable upon the satisfaction of the performance conditions as of the end of the respective periods.