CAPITAL STOCK - Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic:
Net loss attributable to common stock	$ (4,860)	$ (3,553)	$ 40
Weighted average number of shares outstanding, basic (in shares)	378	377	382
Basic net income (loss) per share (in USD per share)	$ (12.86)	$ (9.43)	$ 0.11
Effect of Dilutive Securities:
Stock options and other, shares (in shares)	0	0	2
Stock options and other, per share (in USD per share)	$ 0	$ 0	$ 0
Diluted:
Income (loss) attributable to common stock	$ (4,860)	$ (3,553)	$ 40
Weighted average number of shares outstanding, diluted (in shares)	378	377	384
Diluted net income (loss) per share (in USD per share)	$ (12.86)	$ (9.43)	$ 0.11