OTHER INCOME - Summary of Other Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
OTHER INCOME
COVID-19 relief	$ 611	$ 2,628	$ 3,447	$ 5,319
Unrealized and realized gain (loss) on investments (Note 5)	18		20	(619)
Foreign currency gain (loss)	654	(132)	751	1,736
Other income, net			2,300
Other income, net	(19)	(406)	2,253	(365)
Total other income	$ 1,264	$ 2,090	$ 6,471	$ 6,071