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ACQUISITIONS - Narrative (Details) $ in Millions |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Dec. 09, 2020 USD ($) | Mar. 13, 2020 USD ($) | Sep. 30, 2021 USD ($) | Sep. 30, 2020 USD ($) | Sep. 30, 2021 USD ($) | Sep. 30, 2020 USD ($) | Dec. 31, 2020 business
Business Acquisition [Line Items] |  |  |  |  |  |  |
Number of businesses acquired | business |  |  |  |  |  |  | 2
Acquisition-related costs |  |  | $ (4) | $ (7) | $ (18) | $ (68) |
Other Operating Income (Expense) |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Equity interest loss |  |  |  |  | (18) |  |
ArcelorMittal USA |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Acquisition-related costs |  |  | $ (1) |  | $ (3) |  |
Consideration transferred | $ 2,604 |  |  |  |  |  |
AK Steel |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Exchange ratio |  | 0.400 |  |  |  |  |
Consideration transferred |  | $ 1,535 |  |  |  |  |

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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460 + Details
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
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