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v3.20.4

Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Advance royalty recoupment reserve |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Period | $ 0.3 | $ 0.3 | $ 0.0
Charged to Costs and Expenses | 0.0 | 0.0 | 0.3
Deductions | 0.0 | 0.0 | 0.0
Other | 0.0 | 0.0 | 0.0
Balance at End of Period | 0.3 | 0.3 | 0.3
Reserve for materials and supplies |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Period | 7.9 | 0.2 | 0.6
Charged to Costs and Expenses | 3.5 | 8.9 | 0.5
Deductions | (1.0) | (1.2) | (0.9)
Other | 0.0 | 0.0 | 0.0
Balance at End of Period | 10.4 | 7.9 | 0.2
Allowance for credit losses |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Period | 0.0 | 4.4 | 4.6
Charged to Costs and Expenses |  | (4.4) | (0.2)
Deductions |  | 0.0 | 0.0
Other |  | 0.0 | 0.0
Balance at End of Period |  | 0.0 | 4.4
Tax valuation allowances |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at Beginning of Period | 2,068.4 | 2,094.3 | 2,432.5
Charged to Costs and Expenses | 373.2 | (29.8) | (275.0)
Deductions | 0.0 | 0.0 | 0.0
Other | (154.3) | 3.9 | (63.2)
Balance at End of Period | $ 2,287.3 | $ 2,068.4 | $ 2,094.3

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- Definition Amount of increase (decrease) in valuation and qualifying accounts and reserves from adjustment. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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