The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

Total fresh-start adjustment to property and equipment, net.

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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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Total property and equipment, net at the balance sheet date after fresh-start adjustments.

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Fair value portion 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.

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Adjustments to PP&E (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 01, 2017
Fresh-Start Adjustment [Line Items]
Fresh-start adjustment, increase (decrease), property, plant, equipment and mine development, net				$ 3,461.4
PP&E, fair value				3,461.4
Asset retirement obligations	$ 752.3	$ 750.2	$ 691.1
Land and coal interests
Fresh-Start Adjustment [Line Items]
PP&E, fair value				3,504.7
Asset retirement obligations				281.2
Buildings and improvements
Fresh-Start Adjustment [Line Items]
Postconfirmation, property, plant, equipment and mine development, net				466.1
Machinery and equipment
Fresh-Start Adjustment [Line Items]
Postconfirmation, property, plant, equipment and mine development, net				$ 940.5