EQUITY METHOD INVESTMENTS - Summarized Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Current assets	$ 180	$ 80
Long-term assets	1,008	834
Current liabilities	104	69
Long-term liabilities	735	521
Operating revenue	120	112	$ 17
Operating income	28	31	1
Net income	$ 11	$ 13	$ 1