PROVISION FOR INCOME TAXES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
U.S. and foreign components of income before income taxes [Abstract]
U.S. operations	$ 18,884,000	$ 22,312,000	$ 5,093,000
Foreign operations	26,211,000	39,493,000	25,430,000
INCOME BEFORE PROVISION FOR INCOME TAXES	45,095,000	61,805,000	30,523,000
Undistributed earnings of the Company's foreign subsidiaries	175,900,000
Current provision:
Federal	7,758,000	9,179,000	5,469,000
State	246,000	585,000	3,347,000
Foreign	474,000	98,000	476,000
Current provision	8,478,000	9,862,000	9,292,000
Deferred provision (benefit):
Federal	1,458,000	2,280,000	(1,201,000)
State	845,000	160,000	(811,000)
Foreign	23,000	39,000	(26,000)
Deferred provision (benefit)	2,326,000	2,479,000	(2,038,000)
Total	10,804,000	12,341,000	7,254,000
Adjustments to additional paid in capital, benefit from employee stock option activity	2,200,000	2,900,000	1,600,000
Effective income tax rate reconciliation [Abstract]
Provision computed at Federal statutory rate	35.00%	35.00%	35.00%
State tax provision, net of Federal benefit	0.50%	1.30%	0.50%
Business tax credits	(5.70%)	(5.60%)	(7.50%)
Stock-based compensation	(0.20%)	2.60%	4.50%
Foreign income taxed at different rate	(10.90%)	(14.70%)	(15.50%)
Valuation allowance	3.40%	0.20%	7.90%
Other	1.90%	1.20%	(1.10%)
Total	24.00%	20.00%	23.80%
Components of deferred income tax asset [Abstract]
Tax credit carry-forwards	7,002,000	5,375,000
Other reserves and accruals	5,424,000	5,419,000
Stock compensation	6,808,000	7,609,000
Deferred tax assets, gross	19,234,000	18,403,000
Valuation allowance	(5,955,000)	(3,547,000)
Net deferred tax asset	13,279,000	14,856,000
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Balance at beginning of period	29,911,000	24,869,000	20,680,000
Gross Increases for Tax Positions of Current Year	4,944,000	5,269,000	4,189,000
Gross Decreases for Tax Positions of Prior Years	0	(227,000)	0
Settlements	0	0	0
Lapse of Statute of Limitations	0	0	0
Unrecognized Tax Benefits, Balance at end of period	34,855,000	29,911,000	24,869,000
Unrecognized tax benefits [Abstract]
Unrecognized tax benefits	34,855,000	29,911,000	24,869,000
Income tax benefit that would be recorded if unrecognized tax benefits are recognized	31,600,000
Income tax interest and penalties accrued	4,400,000
Income tax interest and penalties expense	700,000
Research and Development [Member] | California [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	13,000,000
Research and Development [Member] | Federal [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	1,600,000
Research and Development [Member] | Canadian [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 1,800,000