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RESERVE ROLLFORWARDS (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | $ 1,047 | $ 1,177 | $ 1,063
Charges (Credits) to Cost and Expense | (69) | (100) | 132
Charged to Other Accounts | 2 | (14) | 1
Deductions | 11 | 16 | 19
Ending Balance | 969 | 1,047 | 1,177
SEC Schedule, 12-09, Allowance, Credit Loss [Member] |  |  |
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | 11 | 11 | 12
Charges (Credits) to Cost and Expense | 4 | 0 | 0
Charged to Other Accounts | 0 | 0 | 0
Deductions | 1 | 0 | 1
Ending Balance | 14 | 11 | 11
LIFO Inventory [Member] |  |  |
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | 248 | 337 | 288
Charges (Credits) to Cost and Expense | (22) | (89) | 44
Charged to Other Accounts | 0 | 0 | 5
Deductions | 0 | 0 | 0
Ending Balance | 226 | 248 | 337
Non-environmental asset retirement obligation Costs [Member] |  |  |
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | 48 | 46 | 49
Charges (Credits) to Cost and Expense | 2 | 2 | (2)
Charged to Other Accounts | 1 | 0 | 0
Deductions | 0 | 0 | 1
Ending Balance | 51 | 48 | 46
Environmental Contingencies [Member] |  |  |
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | 287 | 296 | 304
Charges (Credits) to Cost and Expense | 8 | 7 | 9
Charged to Other Accounts | 0 | 0 | 0
Deductions | 10 | 16 | 17
Ending Balance | 285 | 287 | 296
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] |  |  |
Movement In Valuation Allowances And Reserves Roll Forward |  |  |
Beginning Balance | 453 | 487 | 410
Charges (Credits) to Cost and Expense | (61) | (20) | 81
Charged to Other Accounts | 1 | (14) | (4)
Deductions | 0 | 0 | 0
Ending Balance | $ 393 | $ 453 | $ 487

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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column B)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column E)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
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- Definition Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column C)(1)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
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- Definition Amount of decrease in valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column D)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
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