OTHER (EXPENSE) INCOME, NET - Components of Other (Expense) 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 and Expenses [Abstract]
Interest and investment income	$ 98	$ 32	$ 272	$ 415
Income tax expense	(150)	(12)	(451)	(127)
Other non-operating expense	0	(551)	0	(549)
Total other (expense) income, net	$ (52)	$ (531)	$ (179)	$ (261)