FAIR VALUE MEASUREMENTS - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Total	$ 207,717	$ 312,963
Money market funds
Assets:
Cash equivalents	63,730	32,501
Commercial paper
Assets:
Investments		35,559
Corporate bonds
Assets:
Investments	104,066	192,573
U.S. Government agencies
Assets:
Investments	39,921	52,330
Level 1
Assets:
Total	63,730	32,501
Level 1 | Money market funds
Assets:
Cash equivalents	63,730	32,501
Level 1 | Commercial paper
Assets:
Investments		0
Level 1 | Corporate bonds
Assets:
Investments	0	0
Level 1 | U.S. Government agencies
Assets:
Investments	0	0
Level 2
Assets:
Total	143,987	280,462
Level 2 | Money market funds
Assets:
Cash equivalents	0	0
Level 2 | Commercial paper
Assets:
Investments		35,559
Level 2 | Corporate bonds
Assets:
Investments	104,066	192,573
Level 2 | U.S. Government agencies
Assets:
Investments	39,921	52,330
Level 3
Assets:
Total	0	0
Level 3 | Money market funds
Assets:
Cash equivalents	0	0
Level 3 | Commercial paper
Assets:
Investments		0
Level 3 | Corporate bonds
Assets:
Investments	0	0
Level 3 | U.S. Government agencies
Assets:
Investments	$ 0	$ 0