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ACQUISITIONS - AK Steel Allocation of Consideration (Details) - USD ($) $ in Millions | 13 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020 | Mar. 13, 2020
Business Acquisition [Line Items] |  |  |
Goodwill | $ 994 | $ 1,406 |
AK Steel |  |  |
Business Acquisition [Line Items] |  |  |
Cash and cash equivalents | 39 |  | $ 38
Measurement Period Adjustments, Cash and cash equivalents | 1 |  |
Accounts receivable, net | 664 |  | 666
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Receivable | (2) |  |
Inventories | 1,320 |  | 1,563
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory | (243) |  |
Other current assets | 52 |  | 68
Measurement Period Adjustments, Other current assets | (16) |  |
Property, plant and equipment | 2,274 |  | 2,184
Measurement Period Adjustments, Property, plant, and equipment | 90 |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Income Taxes | 69 |  | 0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Income Taxes | 69 |  |
Other non-current assets | 471 |  | 475
Measurement Period Adjustments, Other non-current assets | (4) |  |
Accounts payable | (644) |  | (636)
Measurement Period Adjustments, Accounts payable | (8) |  |
Accrued employment costs | (93) |  | (94)
Measurement Period Adjustments, Accrued employment costs | 1 |  |
Pension and OPEB liabilities, current | (78) |  | (75)
Measurement Period Adjustments, Pension and OPEB liabilities, current | (3) |  |
Other current liabilities | (227) |  | (236)
Measurement Period Adjustments, Other current liabilities | 9 |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt | (1,179) |  | (1,179)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Long-term Debt | 0 |  |
Pension and OPEB liabilities, non-current | (871) |  | (873)
Measurement Period Adjustments, Pension and OPEB liabilities, noncurrent | 2 |  |
Other non-current liabilities | (435) |  | (507)
Measurement Period Adjustments, Other non-current liabilities | 72 |  |
Noncontrolling interest | (1) |  | 0
Measurement Period Adjustments, Noncontrolling interest | (1) |  |
Net identifiable assets acquired | 1,361 |  | 1,394
Measurement Period Adjustments, Net identifiable assets acquired | (33) |  |
Goodwill | 174 |  | 141
Measurement Period Adjustments, Goodwill | 33 |  |
Total net assets acquired | 1,535 |  | $ 1,535
Measurement Period Adjustments, Total net assets acquired | $ 0 |  |

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