Represents information pertaining to number of corporate staff accepted voluntary separation package.

No definition available.

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- Definition

Number of employees accepted voluntary separation package.

+ References

No definition available.

+ Details

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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
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 1
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Asset Impairment and Restructuring (Details) $ in Millions	3 Months Ended		9 Months Ended
Asset Impairment and Restructuring (Details) $ in Millions	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($) employee	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($) employee
Property, Plant and Equipment [Line Items]
Severance Costs	$ 0.0	$ 13.3	$ 0.0	$ 13.3
Number of corporate staff accepted voluntary separation package \| employee		53		53
Number of Employees accepted voluntary separation package \| employee		201		201
Knight Hawk
Property, Plant and Equipment [Line Items]
Asset impairment charges	$ 36.2		$ 36.2
Coal Creek Mine
Property, Plant and Equipment [Line Items]
Asset impairment charges		$ 51.8		$ 51.8
Viper Mine
Property, Plant and Equipment [Line Items]
Asset impairment charges		33.5		33.5
West Elk Mine
Property, Plant and Equipment [Line Items]
Asset impairment charges		$ 41.6		$ 41.6