DEBT - Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Interest expense	$ 235	$ 110	$ 61
Less capitalized interest	(66)	(32)	(22)
Other fees and expenses	4	10	2
Total interest expense	$ 173	$ 88	$ 41