Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Condensed Consolidated Statements of Operations [Abstract]
NET REVENUES	$ 68,510	$ 73,911	$ 136,004	$ 141,103
COST OF REVENUES	28,585	31,222	58,230	61,195
GROSS PROFIT	39,925	42,689	77,774	79,908
OPERATING EXPENSES:
Research and development	12,231	11,540	24,752	22,913
Selling, general and administrative	11,672	12,070	23,763	22,968
Total operating expenses	23,903	23,610	48,515	45,881
INCOME FROM OPERATIONS	16,022	19,079	29,259	34,027
OTHER INCOME (EXPENSE):
Interest income	177	126	367	270
Interest expense	(2)	(64)	(18)	(142)
Other income, net	36	34	75	75
Total other income, net	211	96	424	203
INCOME BEFORE INCOME TAXES	16,233	19,175	29,683	34,230
PROVISION FOR INCOME TAXES	5,512	6,819	9,897	12,163
NET INCOME	$ 10,721	$ 12,356	$ 19,786	$ 22,067
NET INCOME PER SHARE:
Basic	$ 0.17	$ 0.20	$ 0.32	$ 0.35
Diluted	$ 0.17	$ 0.20	$ 0.31	$ 0.35
CASH DIVIDENDS PER COMMON SHARE	$ 0.035	$ 0.035	$ 0.07	$ 0.07
WEIGHTED AVERAGE SHARES USED IN COMPUTING PER SHARE AMOUNTS:
Basic	62,167	62,430	62,007	62,388
Diluted	63,027	63,191	63,057	62,840