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INCOME TAXES (Schedule of Effective Rate Reconciliation) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | $ 118.6 | $ 37.9 | $ 38.6
Effective Income Tax Rate Reconciliation, Percent | (84.10%) | (233.30%) | (11.10%)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | $ 0.0 | $ 407.5 | $ 149.1
Impact Of Tax Law Change Percent | 0.00% | 376.60% | 135.10%
Effective Income Tax Rate Reconciliation, Disposition of Business, Amount | $ 161.7 | $ 0.0 | $ 0.0
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent | 28.60% | 0.00% | 0.00%
Prior year adjustments made in current year, amount | $ (1.0) | $ (1.1) | $ (11.8)
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion | $ (54.6) | $ (61.6) | $ (36.1)
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion percent | (9.70%) | (56.90%) | (32.70%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount | $ 0.1 | $ 477.9 | $ (40.6)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent | 0.00% | 441.70% | (36.80%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | 21.00% | 35.00% | 35.00%
Tax Adjustments, Settlements, and Unusual Provisions | $ (1.3) | $ (1.4) | $ (11.3)
Tax Adjustments Settlements And Unusual Provisions Percent | (0.20%) | (1.30%) | (10.20%)
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent | (0.20%) | (1.00%) | (10.70%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | $ 3.1 | $ 1.0 | $ (9.8)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent | 0.60% | 0.90% | (8.90%)
Income Tax Expense (Benefit) | $ (475.2) | $ (252.4) | $ (12.2)
Worthless Stock Deduction, Amount | $ 0.0 | $ 0.0 | $ (73.4)
Worthless Stock Deduction, Percent | 0.00% | 0.00% | (66.50%)
Tax Law Change [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 0.0 | $ (407.5) | $ (149.1)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.00% | (376.60%) | (135.10%)
Current year activity [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ (80.6) | $ (466.3) | $ 122.9
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | (14.30%) | (431.00%) | 111.30%
valuation allowance reversal [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ (460.5) | $ 0.0 | $ 0.0
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | (81.50%) | 0.00% | 0.00%
Repeal of AMT [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 0.0 | $ (235.3) | $ 0.0
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.00% | (217.50%) | 0.00%
Dissolution of entities [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ (161.7) | $ 0.0 | $ 0.0
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | (28.60%) | 0.00% | 0.00%
Prior year adjustment in current year [Member] |  |  |
Income Tax Contingency [Line Items] |  |  |
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | $ 1.0 | $ (3.5) | $ 9.3
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent | 0.20% | (3.20%) | 8.40%

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