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Property, Plant, Equipment and Mine Development - Narrative (Details) - USD ($) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
Asset impairment | $ 0 | $ 0 | $ 0 | $ 1,418,100,000
At-risk assets | 1,100,000,000 |  | 1,100,000,000 |
Other US Mining Operations |  |  |  |
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
At-risk assets | $ 0 |  | $ 0 |
Property, plant, equipment, and mine development assets |  |  |  |
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
Asset impairment |  | 1,393,700,000 |  | 1,393,700,000
Operating lease right-of-use assets |  |  |  |
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
Asset impairment |  | 19,900,000 |  | 19,900,000
Contract-Based Intangible Assets |  |  |  |
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
Asset impairment |  | $ 4,500,000 |  | $ 4,500,000

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123351718&loc=d3e2420-110228 + Details
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