Debtor Reorganization Items, Amounts issued to Settle Claims [Abstract]

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Debtor Reorganization Items, Other Adjustments [Abstract]

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Fresh-Start Adjustment, Reorganization Gain (Loss), Net

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Amount of reorganization items related to legal and advisory professional fees related to entities in bankruptcy.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=64805424&loc=d3e55730-112764

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56145-112766

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Amount of write-off of debt issuance costs and debt discounts related to prepetition debt obligations.

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Amount of fresh-start adjustment to additional paid-in capital.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
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-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

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Amount of fresh-start adjustment to common stock.

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Total fresh-start adjustment to long-term debt.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 7
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Amount of fresh-start adjustment to preferred stock.

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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 amount of liabilities subject to compromise.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56145-112766

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Gain on Settlement of Liabilities Subject to Compromise (Details) - USD ($) $ in Millions	Apr. 01, 2017	Dec. 31, 2017	Dec. 31, 2016
Fresh-Start Adjustment [Line Items]
Liabilities subject to compromise	$ 8,416.7		$ 8,440.2
Less amounts issued to settle claims:
Successor Series A Convertible Preferred Stock	1,305.4
Issuance of Successor Term Loan	(950.0)
Cash payments and accruals for claims and professional fees	(336.4)
Other:
Write-off of Predecessor debt issuance costs, see also (e) below	18.1
Total pre-tax gain on plan effects, see also (j) below	3,031.2
Successor
Fresh-Start Adjustment [Line Items]
Liabilities subject to compromise		$ 0.0
Less amounts issued to settle claims:
Successor Common Stock	0.7
Successor Additional paid-in capital	$ 1,774.9