SIGNIFICANT ACCOUNTING POLICIES - Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Total marketable securities	$ 81,724	$ 51,857
U.S. Treasury securities
Marketable Securities [Line Items]
Total marketable securities	901	28,901
Municipal bonds
Marketable Securities [Line Items]
Total marketable securities	1,978	0
Corporate notes and bonds
Marketable Securities [Line Items]
Total marketable securities	57,685	22,956
Commercial paper
Marketable Securities [Line Items]
Total marketable securities	$ 21,160	$ 0