LEASES - Lease Maturity (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Lessee, Operating Lease, Liability, to be Paid, Year One	$ 8
Finance Lease, Liability, to be Paid, Year One	9
Operating Leases
2020	8
2021	7
2022	7
2023	6
2026 and thereafter	27
Total lease payments	63
Less: Amounts representing interest	(14)
Total lease obligations	49	$ 49
Finance Leases
2020	12
2021	12
2022	11
2023	13
2026 and thereafter	92
Total lease payments	149
Less: Amounts representing interest	(66)
Total lease obligations	$ 83	$ 85