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SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Cash equivalents:
Amortized cost	$ 3,787
Unrealized gain	0
Unrealized Loss	0
Cash equivalents	3,787
Debt securities:
Amortized cost	170,814
Unrealized gain	10
Unrealized Loss	(29)
Debt securities	170,795
Classified as:
Cash equivalents	3,787
Short-term debt securities	170,795	$ 0
Long-term debt securities	0
Total financial assets	174,582
Other-than-temporary impairment losses	0
Corporate debt securities
Debt securities:
Amortized cost	34,378
Unrealized gain	2
Unrealized Loss	(17)
Debt securities	34,363
Commercial paper
Debt securities:
Amortized cost	20,738
Unrealized gain	2
Unrealized Loss	0
Debt securities	20,740
U.S. government bonds
Debt securities:
Amortized cost	80,845
Unrealized gain	3
Unrealized Loss	(8)
Debt securities	80,840
Certificate of deposits
Debt securities:
Amortized cost	24,520
Unrealized gain	3
Unrealized Loss	0
Debt securities	24,523
Other
Debt securities:
Amortized cost	10,333
Unrealized gain	0
Unrealized Loss	(4)
Debt securities	10,329
Money market fund
Cash equivalents:
Amortized cost	3,787
Unrealized gain	0
Unrealized Loss	0
Cash equivalents	3,787
Classified as:
Cash equivalents	$ 3,787

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