LEASES - Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Assets
Operating lease ROU assets	$ 106	$ 120
Financing lease ROU assets	19	28
Total leased assets	125	148	$ 165
Current:
Operating lease liabilities	$ 16	$ 20
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Financing lease liabilities	$ 10	$ 13
Noncurrent:
Operating lease liabilities	$ 95	$ 103
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Financing lease liabilities	$ 12	$ 20
Total lease liabilities	$ 133	$ 156	$ 172