NET INCOME (LOSS) PER COMMON SHARE - Calculation of Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income (loss) - continuing operations	$ (242,224)	$ (420,212)	$ (362,587)
Income from discontinued operations, net of income taxes (benefit)	0	0	1,152
Net income (loss)	$ (242,224)	$ (420,212)	$ (361,435)
Basic weighted average shares outstanding (in shares)	134,570,672	136,967,455	138,069,608
Net income (loss) from continuing operations per share - basic (in dollars per share)	$ (1.80)	$ (3.07)	$ (2.63)
Net income (loss) from discontinued operations per share - basic (in dollars per share)	0	0	0.01
Net income (loss) per share available to common shareholders - Basic (in dollars per share)	$ (1.80)	$ (3.07)	$ (2.62)
Net income (loss)	$ (242,224)	$ (420,212)	$ (361,435)
Effect of RSUs and options under the treasury stock method (in shares)	0	0	0
Weighted average shares outstanding, diluted (in shares)	134,570,672	136,967,455	138,069,608
Net income (loss) from continuing operations per share - Diluted (in dollars per share)	$ (1.80)	$ (3.07)	$ (2.63)
Net income (loss) from discontinued operations per share - Diluted (in dollars per share)	0	0	0.01
Net income (loss) per share - diluted (in dollars per share)	$ (1.80)	$ (3.07)	$ (2.62)