INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Loss carryforwards	$ 49,899,000
Increase (decrease) in deferred tax asset valuation allowance	(532,000)	$ 71,000	$ (5,818,000)
Unrecognized tax benefits	0	0
Accrual for interest and penalties related to uncertain tax positions	$ 0	0
Minimum
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, term	5 years
Maximum
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, term	20 years
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Loss carryforwards	$ 46,344,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Loss carryforwards	3,555,000
Germany
Operating Loss Carryforwards [Line Items]
Increase (decrease) in deferred tax asset valuation allowance	$ (1,114,000)	$ 537,000