INCOME TAXES - Valuation Allowance(Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Line Items]
Valuation allowance	$ 12,793	$ 11,436
AUSTRALIA
Valuation Allowance [Line Items]
Valuation allowance	300	0
CHINA
Valuation Allowance [Line Items]
Valuation allowance	300	0
China
Valuation Allowance [Line Items]
Valuation allowance	600	600
Hong Kong
Valuation Allowance [Line Items]
Valuation allowance	100	0
Mexico
Valuation Allowance [Line Items]
Valuation allowance	3,100	2,800
Norway
Valuation Allowance [Line Items]
Valuation allowance	100	0
Norway
Valuation Allowance [Line Items]
Valuation allowance	200	100
Sweden
Valuation Allowance [Line Items]
Valuation allowance	100	100
Taiwan
Valuation Allowance [Line Items]
Valuation allowance	900	800
Ukraine
Valuation Allowance [Line Items]
Valuation allowance	100	100
United States - Federal
Valuation Allowance [Line Items]
Valuation allowance	100	100
United States
Valuation Allowance [Line Items]
Valuation allowance	6,900	6,800
Other Jurisdictions
Valuation Allowance [Line Items]
Valuation allowance	$ 0	$ 0