INCOME TAX - Change in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, beginning of period	$ (23,390)	$ (16,550)	$ (16,611)
Valuation allowance, end of period	(72,042)	(23,390)	(16,550)
Net operating loss carryforwards
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change		1,145	(3,793)
Net operating loss carryforwards \| Foreign Tax Authority
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change	(26,439)	(7,979)	(6,469)
Net operating loss carryforwards \| Domestic Tax Authority
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change	(307)
Income tax credit carryforward \| Foreign Tax Authority
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change	(15,226)		7,140
Income tax credit carryforward \| State Tax Authority
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change	$ (6,680)	$ (6)	(685)
Rate change
Movement in Deferred Tax Valuation Allowance [Roll Forward]
Valuation allowance, change			$ 3,868