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ENVIRONMENTAL MATTERS AND ASSET RETIREMENT OBLIGATIONS (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning of period $ 296  
End of period 294  
Accrual for Environmental Loss Contingencies, Balance Sheet Classification [Abstract]    
Accrued Environmental Loss Contingencies, Current 25 $ 25
Accrued Environmental Loss Contingencies, Noncurrent 269 271
Environmental Remediation [Member]    
Accrual for Environmental Loss Contingencies [Roll Forward]    
Beginning of period 271  
Changes in estimates recognized in earnings and other 1  
Cash reductions (3)  
End of period $ 269  
Expected Payment Period of Environmental Contingencies approximately 30 years  
Environmental Remediation [Member] | Minimum [Member]    
Site Contingency [Line Items]    
Loss Contingency, Estimate of Possible Loss $ 269 271
Environmental Remediation [Member] | Maximum [Member]    
Site Contingency [Line Items]    
Loss Contingency, Estimate of Possible Loss 507 508
Environmental ARO [Member]    
Site Contingency [Line Items]    
Best Estimate Accrued to-date For Asset Retirement Obligation 25 25
Non Environmental ARO [Member]    
Site Contingency [Line Items]    
Best Estimate Accrued to-date For Asset Retirement Obligation $ 46 $ 46