OTHER INCOME - Summary of Other Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OTHER INCOME
COVID-19 relief	$ 3,541	$ 6,420
Unrealized and realized gain (loss) on investments (Note 5)	28	(619)	$ 5,259
Foreign currency gain	513	1,078	1,697
Other income, net	2,199	14	184
Total other income	$ 6,281	$ 6,893	$ 7,140