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RESERVE ROLLFORWARDS (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance $ 1,125 $ 1,090 $ 1,122
Charged to Cost and Expense (150) (47) 10
Charged to Other Accounts 51 112 1
Deductions 81 30 43
Ending Balance 945 1,125 1,090
Allowance for Doubtful Accounts [Member]      
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance 10 12 8
Charged to Cost and Expense 1 1 5
Charged to Other Accounts 2 0 0
Deductions 0 3 1
Ending Balance 13 10 12
LIFO Inventory [Member]      
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance 462 506 505
Charged to Cost and Expense (166) (44) 1
Charged to Other Accounts 0 0 0
Deductions 0 0 0
Ending Balance 296 462 506
Non-environmental asset retirement obligation Costs [Member]      
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance 44 0  
Charged to Cost and Expense 4 0  
Asset Retirement Obligation, Liabilities Incurred 0 44  
Deductions 2 0  
Ending Balance 46 44 0
Environmental Contingencies [Member]      
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance 345 368 394
Charged to Cost and Expense 9 2 4
Charged to Other Accounts 11 2 1
Deductions 29 27 31
Ending Balance 336 345 368
Valuation Allowance of Deferred Tax Assets [Member]      
Movement In Valuation Allowances And Reserves Roll Forward      
Beginning Balance 264 204 215
Charged to Cost and Expense 2 (6) 0
Charged to Other Accounts 38 66 0
Deductions 50 0 11
Ending Balance $ 254 $ 264 $ 204