LEASES - Schedule of Lease Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Amortization of finance lease asset	$ 3	$ 3
Interest on lease liabilities	4	4
Total finance lease expense	7	7
Operating lease expense	64	47
Total lease expense	71	54
Variable lease expense	7	5
Short-term lease expense	$ 1	$ 1