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INCOME TAXES - Schedule of Effective Rate Reconciliation (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract] |  |  |
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | $ (41) | $ 66 | $ 119
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion | (42) | (49) | (55)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount | (9) | 0 | 0
Effective Income Tax Rate Reconciliation, Disposition of Business, Amount | 0 | 846 | 162
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | (11) | 0 | 0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | (8) | 1 | 2
Income Tax Expense (Benefit) | $ (111) | $ 18 | $ (475)
Effective Income Tax Rate Reconciliation, Percent [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | 21.00% | 21.00% | 21.00%
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion percent | 22.00% | (16.00%) | (10.00%)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent | 4.00% | 0.00% | 0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent | 0.00% | 271.00% | 29.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent | 6.00% | 0.00% | 0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent | 4.00% | 1.00% | 0.00%
Effective Income Tax Rate Reconciliation, Percent | 57.00% | 6.00% | (84.00%)
Current year activity [Member] |  |  |
Effective Income Tax Rate Reconciliation, Amount [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 0 | $ 0 | $ (80)
Effective Income Tax Rate Reconciliation, Percent [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.00% | 0.00% | (14.00%)
valuation allowance reversal [Member] |  |  |
Effective Income Tax Rate Reconciliation, Amount [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 0 | $ 0 | $ (461)
Effective Income Tax Rate Reconciliation, Percent [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.00% | 0.00% | (81.00%)
Dissolution of entities [Member] |  |  |
Effective Income Tax Rate Reconciliation, Amount [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 0 | $ (846) | $ (162)
Effective Income Tax Rate Reconciliation, Percent [Abstract] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.00% | (271.00%) | (29.00%)

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