FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Cash and Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair value disclosure
Cash and cash equivalents	$ 76,620	$ 303,954
Short-term investments	48,339	65,408
Concentrations of Credit Risk of Financial Instruments
Cash, cash equivalents and short-term investments not FDIC-insured	42,600	156,400
Cash deposits
Fair value disclosure
Cash and cash equivalents	72,790	240,687
Variable rate demand notes
Fair value disclosure
Cash and cash equivalents	230	29,066
Money market funds
Fair value disclosure
Cash and cash equivalents	3,600	34,201
Certificates of deposit
Fair value disclosure
Short-term investments	$ 48,339	53,297
Treasury instruments
Fair value disclosure
Short-term investments		$ 12,111