LEASES - Lease Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Leases [Abstract]
Lessee, Operating Lease, Liability, to be Paid, Year One	$ 5
Finance Lease, Liability, to be Paid, Year One	6
Operating Leases
2020	8
2021	7
2022	7
2023	6
2026 and thereafter	27
Total lease payments	60
Less: Amounts representing interest	(13)
Total lease obligations	47	$ 49
Finance Leases
2020	11
2021	11
2022	11
2023	10
2026 and thereafter	94
Total lease payments	143
Less: Amounts representing interest	(61)
Total lease obligations	$ 82	$ 85