PROVISION FOR INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
U.S. and foreign components of income before income taxes [Abstract]
U.S. operations	$ (6,529)	$ (6,944)	$ (477)
Foreign operations	66,293	67,243	50,429
INCOME BEFORE INCOME TAXES	59,764	60,299	49,952
Current provision:
Federal	(6,382)	35,311	0
State	4	4	0
Foreign	938	1,483	1,638
Current provision	(5,440)	36,798	1,638
Deferred provision (benefit):
Federal	(4,593)	(3,640)	(175)
State	0	0	(27)
Foreign	(187)	(468)	(382)
Deferred provision (benefit)	$ (4,780)	$ (4,108)	$ (584)
Effective income tax rate reconciliation [Abstract]
Provision (benefit) computed at Federal statutory rate	21.00%	35.00%	35.00%
Business tax credits	(9.10%)	(5.70%)	(6.00%)
Stock-based compensation	(2.20%)	(5.00%)	2.20%
Foreign income taxed at different rate	(25.00%)	(37.30%)	(33.10%)
GILTI inclusion	10.60%	0.00%	0.00%
U.S. Tax Act - transition tax	(16.20%)	54.10%	0.00%
U.S. Tax Act - deferred tax asset and liability adjustment	0.00%	8.10%	0.00%
Valuation allowance	2.80%	2.20%	1.80%
Other	1.00%	2.80%	2.20%
Total	(17.10%)	54.20%	2.10%
Components of deferred income tax asset [Abstract]
Other reserves and accruals	$ 3,695	$ 979
Tax credit carry-forwards	18,052	10,442
Stock compensation	3,050	4,064
Capital losses	157	163
Net operating loss	3,144	7,059
Valuation allowance	(19,955)	(18,421)
Deferred tax assets, net of valuation allowance	8,143	4,286
Depreciation	(1,423)	(1,965)
Other	(30)	(95)
Deferred tax liabilities	(1,453)	(2,060)
Net deferred tax asset	6,690	2,226
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Balance at beginning of period	16,683	15,393	$ 13,560
Gross Increase for Tax Positions of Current Year	1,994	1,699	1,856
Gross Decrease for Tax Positions of Prior Years	(70)	(409)	(23)
Unrecognized Tax Benefits, Balance at end of period	18,607	16,683	15,393
Unrecognized tax benefits [Abstract]
Unrecognized Tax Benefits, Balance at end of period	18,607	16,683	$ 15,393
Income tax benefit that would be recorded if unrecognized tax benefits are recognized	9,400
Income tax interest and penalties accrued	100	100
U.S. Tax Cuts and Jobs Act [Abstract]
Provisional One Time Transition Tax Related to Tax Cuts and Jobs Act	34,100
Current Federal Tax Expense Related to Impact of Tax Cuts and Jobs Act	(9,700)	$ 37,500
Provisional One Time Transition Tax Related to Tax Cuts and Jobs Act, After Utilization	6,700
Income Tax, Global Intangible Low Tax Income, Before Credits	6,300
Tax Benefit, Initial Recognition of Global Intangible Low-Taxed Income Deferred Tax Asset	2,300
State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	54,700
Research Tax Credit Carryforward [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	7,200
Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	24,300
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	900
Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	$ 2,600
Earliest Tax Year [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 01, 2033
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