LEASES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
Lease assets, non-current	$ 197	$ 223
Lease liabilities, current	34	38
Lease liabilities, non-current	198	217
Total lease liabilities	$ 232	$ 255
Weighted average remaining lease term	9 years 4 months 20 days	9 years 6 months 18 days
Weighted average discount rate	5.70%	5.70%
Finance Leases
Lease assets, non-current	$ 17	$ 14
Lease liabilities, current	5	5
Lease liabilities, non-current	33	33
Total lease liabilities	$ 38	$ 38
Weighted average remaining lease term	8 years 4 months 20 days	7 years 2 months 4 days
Weighted average discount rate	8.40%	8.80%