Gain on VEBA settlement

No definition available.

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- Definition

Other Commitment, Term

+ References

No definition available.

+ Details

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- Definition

Other Commitments, Payments in Period

+ References

No definition available.

+ Details

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- Definition

Other Commitments, Settlement Agreement, Amount

+ References

No definition available.

+ Details

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- Definition

Potential exposure from Patriot bankruptcy related to certain federal and state black lung occupational disease liabilities

+ References

No definition available.

+ Details

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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.

+ Details

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- Definition

Aggregate carrying amount of the estimated litigation liability for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

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- Definition

Amount of loss contingency liability.

+ References

+ Details

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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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Discontinued Operations - Patriot Related Matters (Details) - Spinoff - Patriot - USD ($) $ in Millions		9 Months Ended	12 Months Ended	24 Months Ended
	Jan. 25, 2017	Sep. 30, 2016	Dec. 31, 2013	Dec. 31, 2015	Sep. 30, 2017	Dec. 31, 2007
Black Lung Occupational Disease Liability
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Potential exposure from Patriot bankruptcy						$ 150.0
Potential exposure from Patriot bankruptcy					$ 125.4
UMWA 1974 Pension Plan (UMWA Plan) Litigation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of claim, amount awarded to other party	$ 75.0
Litigation settlement, liability	$ 54.3				$ 44.3
Funding of VEBA Pursuant to Settlement with UMWA and Patriot Coal Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Funding of the newly established VEBA			$ 310.0
Number of years of payments to fund VEBA			4 years
Payments made to fund VEBA				$ 165.0
Settlement agreement, amount		$ 75.0
Gain on VEBA settlement		$ 68.1