INCOME TAXES - Effective Income Tax Rate (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	0.00%	0.00%	1.91%
Change in federal and state statutory rate	0.35%	0.34%	0.03%
Foreign rate differential	(0.62%)	(0.20%)	(0.06%)
Other adjustments	7.36%	(5.18%)	(5.97%)
Valuation allowance	(28.57%)	(16.18%)	(16.91%)
Income tax benefit	(0.48%)	(0.22%)	0.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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