DEBT - Schedule of Convertible Senior Notes due in 2026 (Details) - Convertible Notes - Convertible Senior Notes Due 2026 - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Amortization of debt discount	$ 5,650	$ 13,023
Amortization of debt issuance costs	404	943
Total interest cost recognized	$ 6,054	$ 13,966

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Name:	us-gaap_InterestExpenseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration