FAIR VALUE MEASUREMENT OF FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Measured at Fair Value (Details) - Recurring Fair Value Measurements $ in Thousands	Mar. 31, 2021 USD ($)
Assets:
Short-term investments	$ 134,491
Cash and cash equivalents	427,243
Investments	14,623
Other current assets	48,457
Other assets	2,935
Total assets measured at fair value	627,749
Liabilities:
Contingent earnout liability	8,973
Corporate debt securities
Assets:
Short-term investments	129,467
U.S. government and federal agency securities
Assets:
Short-term investments	5,024
Level 1
Assets:
Short-term investments	5,024
Cash and cash equivalents	427,243
Investments	12,711
Other current assets	48,457
Other assets	2,935
Total assets measured at fair value	496,370
Liabilities:
Contingent earnout liability	0
Level 1 | Corporate debt securities
Assets:
Short-term investments	0
Level 1 | U.S. government and federal agency securities
Assets:
Short-term investments	5,024
Level 2
Assets:
Short-term investments	129,467
Cash and cash equivalents	0
Investments	412
Other current assets	0
Other assets	0
Total assets measured at fair value	129,879
Liabilities:
Contingent earnout liability	0
Level 2 | Corporate debt securities
Assets:
Short-term investments	129,467
Level 2 | U.S. government and federal agency securities
Assets:
Short-term investments	0
Level 3
Assets:
Short-term investments	0
Cash and cash equivalents	0
Investments	1,500
Other current assets	0
Other assets	0
Total assets measured at fair value	1,500
Liabilities:
Contingent earnout liability	8,973
Level 3 | Corporate debt securities
Assets:
Short-term investments	0
Level 3 | U.S. government and federal agency securities
Assets:
Short-term investments	$ 0