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FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - RECONCILIATION FOR ASSETS AND LIABILITIES MEASURE AT FAIR VALUE USING LEVEL 3 (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Total        
Balance at beginning of period $ 170 $ 856 $ 142 $ 368
Purchases 231 163 924 684
Sales (443) (517) (1,472) (1,022)
Issuances (3) 0 (8) (1)
Settlements 213 58 375 85
Transfers into Level 3 157 203 436 503
Transfers out of Level 3 (25) (449) (148) (475)
Balance at end of period 317 213 317 213
Cost of goods sold        
Total        
Total gains and (losses), realized/unrealized included in cost of goods sold 17 (101) 68 71
Total changes in unrealized gains and (losses) relating to assets and liabilities 6 (137) (22) (16)
Derivatives, Net        
Derivatives, Net        
Balance at beginning of period 0 127 (51) 167
Purchases 3 0 8 0
Sales 0 0 0 0
Issuances (3) 0 (8) (1)
Settlements (1) (37) 70 (110)
Transfers into Level 3 (1) (5) (8) (7)
Transfers out of Level 3 3 (1) 22 2
Balance at end of period (3) (36) (3) (36)
Derivatives, Net | Cost of goods sold        
Derivatives, Net        
Total gains and (losses), realized/unrealized included in cost of goods sold (4) (120) (36) (87)
Total        
Changes in unrealized gains and (losses) relating to assets and liabilities relating to derivatives, net (2) (127) (6) 9
Readily Marketable Inventories        
Readily Marketable Inventories        
Balance at beginning of period 623 917 237 245
Purchases 233 171 1,376 904
Sales (443) (517) (1,472) (1,022)
Issuances 0 0 0 0
Settlements 0 0 0 0
Transfers into Level 3 162 208 503 569
Transfers out of Level 3 (29) (499) (170) (547)
Balance at end of period 569 292 569 292
Readily Marketable Inventories | Cost of goods sold        
Readily Marketable Inventories        
Total gains and (losses), realized/unrealized included in cost of goods sold 23 12 95 143
Total        
Changes in unrealized gains and (losses) relating to assets and liabilities relating to readily marketable inventories 11 (12) (19) (26)
Trade Accounts Receivable/ Payable, Net        
Trade Accounts Receivable/ Payable, Net        
Balance at beginning of period (453) (188) (44) (44)
Purchases (5) (8) (460) (220)
Sales 0 0 0 0
Issuances 0 0 0 0
Settlements 214 95 305 195
Transfers into Level 3 (4) 0 (59) (59)
Transfers out of Level 3 1 51 0 70
Balance at end of period (249) (43) (249) (43)
Trade Accounts Receivable/ Payable, Net | Cost of goods sold        
Trade Accounts Receivable/ Payable, Net        
Total gains and (losses), realized/unrealized included in cost of goods sold (2) 7 9 15
Total        
Changes in unrealized gains and (losses) relating to assets and liabilities relating to trade accounts receivable and payable, net $ (3) $ 2 $ 3 $ 1