Consolidated Statements of Operations and Comprehensive Income / (Loss) (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign currency translation adjustments ,tax	$ 0	$ 0	$ 0
Other comprehensive income / (loss), tax	$ 0	$ 0	$ 0

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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+ Details