FINANCIAL INSTRUMENTS - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cash equivalents:
Cash equivalents		$ 197,615
Short-term investments:
Short-term investments	$ 11,818	0
Total	309,231
Time deposits
Short-term investments:
Short-term investments	11,818
Level 1
Cash equivalents:
Cash equivalents		147,615
Short-term investments:
Total	260,582
Level 1 | Time deposits
Short-term investments:
Short-term investments	0
Level 2
Cash equivalents:
Cash equivalents		50,000
Short-term investments:
Total	48,649
Level 2 | Time deposits
Short-term investments:
Short-term investments	11,818
Money market funds
Cash equivalents:
Cash equivalents	260,582	147,615
Money market funds | Level 1
Cash equivalents:
Cash equivalents	260,582	147,615
Money market funds | Level 2
Cash equivalents:
Cash equivalents	0	0
Time deposits
Cash equivalents:
Cash equivalents	36,831	50,000
Time deposits | Level 1
Cash equivalents:
Cash equivalents	0	0
Time deposits | Level 2
Cash equivalents:
Cash equivalents	$ 36,831	$ 50,000