LONG-TERM DEBT - Detail of Convertible Debt Carrying Amount (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal		$ 352,130
Convertible debt embedded derivative | ASU 2020-06 (ASC 470-20)
Debt Instrument [Line Items]
Carrying amount of the equity component, net of issuance costs	[1]	7,969	$ 13,912
Convertible debt embedded derivative | ASU 2016-06 (ASC 815-15)
Debt Instrument [Line Items]
Carrying amount of the equity component, net of issuance costs	[1]	37,276	45,377
Convertible debt
Debt Instrument [Line Items]
Principal		93,130	230,000
Unamortized issuance costs		(1,440)	(4,756)
Unamortized discount		(7,156)	(23,625)
Net carrying amount of the liability component	[2]	84,534	$ 201,619
Carrying amount of the equity component, net of issuance costs		$ 13,700

[1] Relates to the portion of the Notes accounted for under ASC 470-20 (defined below) and is included in the “Additional paid-in capital” line of the consolidated balance sheets.3    Relates to the portion of the Notes accounted for under ASC 815-15 (defined below) and is included in the “Additional paid-in capital” line of the consolidated balance sheets.

[2] Included in the “Long-term debt and finance lease obligations” line of the consolidated balance sheets.