EARNINGS PER SHARE - Anti-dilutive securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities outstanding but excluded from computation of earnings per share	20,812	20,081	19,965
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities outstanding but excluded from computation of earnings per share	11,293	11,293	11,293
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities outstanding but excluded from computation of earnings per share	6,581	7,837	8,672
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities outstanding but excluded from computation of earnings per share	2,938	951