NET EARNINGS (LOSS) PER SHARE AND SHARE REPURCHASES - Potential Shares Not Included in the Computation of Diluted Earnings (Loss) Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares not included in the computation of diluted earnings (loss) per share	4,676	2,490	4,676	2,848
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares not included in the computation of diluted earnings (loss) per share	0	0	0	359
Performance share units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares not included in the computation of diluted earnings (loss) per share	1,139	999	1,139	1,074