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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 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	2,260	2,384	2,260	2,755
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	358
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	729	959	729	1,054