NET LOSS PER COMMON SHARE - Antidilutive Shares (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	17,110,450	16,512,348	16,878,538	16,564,478
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	1,517,338	672,859	1,437,383	611,446
Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	7,113,402	7,891,920	7,113,402	8,151,426
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	8,479,710	7,947,569	8,327,753	7,801,606