FAIR VALUE MEASUREMENTS - RECURRING BASIS (Details) - Recurring basis - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value on a Recurring Basis
Total	$ 173,866	$ 209,208
Money market funds
Fair Value on a Recurring Basis
Total	15,327	24,207
U.S. Treasury securities
Fair Value on a Recurring Basis
Total	20,543	17,088
Municipal securities
Fair Value on a Recurring Basis
Total	2,947	2,985
Government-sponsored enterprise securities
Fair Value on a Recurring Basis
Total	6,461	12,493
Commercial paper
Fair Value on a Recurring Basis
Total	77,200	91,861
Corporate notes
Fair Value on a Recurring Basis
Total	51,388	60,574
Level 1
Fair Value on a Recurring Basis
Total	15,327	24,207
Level 1 | Money market funds
Fair Value on a Recurring Basis
Total	15,327	24,207
Level 2
Fair Value on a Recurring Basis
Total	158,539	185,001
Level 2 | U.S. Treasury securities
Fair Value on a Recurring Basis
Total	20,543	17,088
Level 2 | Municipal securities
Fair Value on a Recurring Basis
Total	2,947	2,985
Level 2 | Government-sponsored enterprise securities
Fair Value on a Recurring Basis
Total	6,461	12,493
Level 2 | Commercial paper
Fair Value on a Recurring Basis
Total	77,200	91,861
Level 2 | Corporate notes
Fair Value on a Recurring Basis
Total	$ 51,388	$ 60,574