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INCOME AND MINING TAXES - Tax Cuts and Jobs Act (the "Act") and Tax Reform (Details) - USD ($) $ in Millions |  | 12 Months Ended
--- | --- | ---
Dec. 29, 2017 | Dec. 31, 2020 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Taxes |  |  |  |  |
Statutory tax rate (as a percent) |  |  | 21.00% | 35.00% | 34.00%
Tax Cuts and Jobs Act reduction of deferred tax liability |  |  |  | $ 4.2 |
Tax Cuts and Jobs Act reduction of deferred tax asset |  |  |  | $ 23.7 |
Taxable income offset by non-operating losses |  |  | $ 13.6 |  |
Argentina |  |  |  |  |
Income Taxes |  |  |  |  |
Statutory tax rate (as a percent) |  |  | 35.00% | 35.00% |
Argentinian Tax Cuts reduction of deferred tax liability | $ 3.9 |  |  |  |
Argentinian Tax Cuts reduction of deferred tax assets |  |  |  | $ 12.4 |
Forecast | Argentina |  |  |  |  |
Income Taxes |  |  |  |  |
Statutory tax rate (as a percent) |  | 25.00% |  |  |

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