ESTIMATES, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND BALANCE SHEET DETAIL Estimates, Significant Accounting Policies and Balance Sheet Detail - Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Disclosure [Abstract]
Liability, Other Retirement Benefits, Noncurrent	$ 97	$ 103
Asset Retirement Obligation	37	30
Other Accrued Liabilities, Current	109	88
Other Liabilities, Noncurrent	$ 243	$ 221