PROVISION (BENEFIT) FOR INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Current Federal Tax Benefit Related To Impact of Tax Cuts And Jobs Act			$ 9,700
U.S. and foreign components of income before income taxes [Abstract]
U.S. operations	$ (6,252)	$ 82,692	(6,529)
Foreign operations	81,503	139,722	66,293
INCOME BEFORE INCOME TAXES	75,251	222,414	59,764
Current provision (benefit):
Federal	2,788	18,293	(6,382)
State	(181)	184	4
Foreign	1,677	1,293	938
Current provision (benefit)	4,284	19,770	(5,440)
Deferred provision (benefit):
Federal	348	9,683	(4,593)
State	0	0	0
Foreign	(557)	(507)	(187)
Deferred provision (benefit)	(209)	9,176	(4,780)
Income tax provision (benefit), Total	$ 4,075	$ 28,946	$ (10,220)
Effective income tax rate reconciliation [Abstract]
Provision (benefit) computed at Federal statutory rate	21.00%	21.00%	21.00%
Business tax credits	(7.40%)	(2.40%)	(9.10%)
Stock-based compensation	(0.10%)	(0.20%)	(2.20%)
Foreign income taxed at different rate	(22.00%)	(12.70%)	(25.00%)
GILTI inclusion	10.70%	6.20%	10.60%
U.S. Tax Act - transition tax	0.00%	0.10%	(16.20%)
Deferred tax asset and liability adjustment	0.30%	0.00%	0.00%
Valuation allowance	2.60%	0.80%	2.80%
Other	0.30%	0.20%	1.00%
Total	5.40%	13.00%	(17.10%)
Components of deferred income tax asset [Abstract]
Other reserves and accruals	$ 3,707	$ 3,099
Tax credit carry-forwards	20,713	18,968
Stock compensation	1,494	1,644
Capital losses	158	157
Net operating loss	2,303	899
Other	1,023	1,000
Valuation allowance	(24,160)	(20,822)
Deferred tax assets, net of valuation allowance	5,238	4,945
Depreciation	(1,974)	(2,273)
Deferred tax liabilities	(1,974)	(2,273)
Net deferred tax assets	3,264	2,672
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Balance at beginning of period	19,049	18,607	$ 16,683
Gross Increase for Tax Positions of Current Year	2,002	1,379	1,994
Gross Decrease for Tax Positions of Prior Years	0	(937)	(70)
Unrecognized Tax Benefits, Balance at end of period	21,051	19,049	18,607
Unrecognized tax benefits [Abstract]
Unrecognized Tax Benefits, Balance at end of period	21,051	19,049	$ 18,607
Income tax benefit that would be recorded if unrecognized tax benefits are recognized	11,100
Income tax interest and penalties accrued	100	$ 100
State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	44,700
Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	30,200
Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | New Jersey Division of Taxation [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	700
Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	$ 3,400
Earliest Tax Year [Member] | State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 01, 2032
Earliest Tax Year [Member] | Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | New Jersey Division of Taxation [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 01, 2026
Earliest Tax Year [Member] | Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 01, 2030