INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits – January 1	$ 25	$ 25	$ 25
Gross increases – tax positions in prior year	44	0	0
Gross increases – tax positions in current year	32	0	0
Unrecognized tax benefits – December 31	101	$ 25	$ 25
Unrecognized tax benefit that would affect effective tax rate	$ 25