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Valuation and Qualifying Accounts Schedule II (Tables) | 12 Months Ended
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Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] |
Summary of Valuation Allowance | SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS
Description |  | Balance at Beginning of Period |  | Charged to Costs and Expenses |  |  |  | Deductions(1) |  | Other |  | Balance at End of Period
|  | (Dollars in millions)
Year Ended December 31, 2020 |  |  |  |  |  |  |  |  |  |  |  |
Reserves deducted from asset accounts: |  |  |  |  |  |  |  |  |  |  |  |
Advance royalty recoupment reserve |  | $ | 0.3 |  |  | $ | — |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 0.3 |
Reserve for materials and supplies |  | 7.9 |  |  | 3.5 |  |  |  |  | (1.0) |  |  | — |  |  | 10.4 |
Tax valuation allowances |  | 2,068.4 |  |  | 373.2 |  |  |  |  | — |  |  | (154.3) |  | (2) | 2,287.3 |
Year Ended December 31, 2019 |  |  |  |  |  |  |  |  |  |  |  |
Reserves deducted from asset accounts: |  |  |  |  |  |  |  |  |  |  |  |
Advance royalty recoupment reserve |  | $ | 0.3 |  |  | $ | — |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 0.3 |
Reserve for materials and supplies |  | 0.2 |  |  | 8.9 |  |  |  |  | (1.2) |  |  | — |  |  | 7.9 |
Allowance for credit losses |  | 4.4 |  |  | (4.4) |  |  |  |  | — |  |  | — |  |  | — |
Tax valuation allowances |  | 2,094.3 |  |  | (29.8) |  |  |  |  | — |  |  | 3.9 |  |  | 2,068.4 |
Year Ended December 31, 2018 |  |  |  |  |  |  |  |  |  |  |  |
Reserves deducted from asset accounts: |  |  |  |  |  |  |  |  |  |  |  |
Advance royalty recoupment reserve |  | $ | — |  |  | $ | 0.3 |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 0.3 |
Reserve for materials and supplies |  | 0.6 |  |  | 0.5 |  |  |  |  | (0.9) |  |  | — |  |  | 0.2 |
Allowance for credit losses |  | 4.6 |  |  | (0.2) |  |  |  |  | — |  |  | — |  |  | 4.4 |
Tax valuation allowances |  | 2,432.5 |  |  | (275.0) |  |  |  |  | — |  |  | (63.2) |  | (3) | 2,094.3 |
(1)Reserves utilized, unless otherwise indicated. (2)Includes the impact of a decrease in Australia NOLs due to a cancellation of intercompany debt, partially offset by the impact of the increase in the Australian dollar exchange rates. (3)Includes the impact of the decrease in Australian dollar exchange rates, partially offset by the impact of final attribute reduction adjustments in the U.S.

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- References No definition available. + Details
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- Definition Tabular disclosure of valuation allowances to reduce deferred tax assets to net realizable value, including identification of the deferred tax asset more likely than not will not be fully realized and the corresponding amount of the valuation allowance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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