Property, Plant, Equipment and Mine Development - Textuals (Details) - Successor - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Property, Plant, Equipment and Mine Development, Net [Line Items]
Land and coal interests	$ 3,900.4	$ 3,890.5
Buildings and improvements	457.0	470.6
Machinery and equipment	1,304.1	1,149.3
Less: Accumulated depreciation, depletion and amortization	(809.6)	(398.5)
Property, plant, equipment and mine development, net	$ 4,851.9	$ 5,111.9

Land and coal interests.

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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- Definition

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

+ References

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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.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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