Additional potential collateral requirements for a credit downgrade.

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- Definition

Coal Trading [Line Items]

+ References

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- Definition

Credit Exposure Related to Coal Trading Activities

+ References

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- Definition

Margin posted to counterparties related to credit rating

+ References

No definition available.

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- Definition

Margin posted to counterparties related to material adverse event.

+ References

No definition available.

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- Definition

Number of major credit rating agencies that adjusted the Company's corporate credit rating during the period.

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- Definition

Potential collateralization that may be requested by counterparties due to a material adverse event.

+ References

No definition available.

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- Definition

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226016-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41678-113959

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- Definition

The net amount as of the balance sheet date of the fair value of derivative assets and derivative liabilities that in accordance with the entity's accounting policy were offset against collateral under a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41678-113959

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- Definition

Amount receivable from broker-dealers and clearing organizations, including, but not limited to, securities failed-to-deliver, certain deposits for securities borrowed, open transactions, good faith and margin deposits, commissions and floor brokerage receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=35710130&loc=d3e41645-110958

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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Coal Trading Textuals (Details) $ in Millions	3 Months Ended
Coal Trading Textuals (Details) $ in Millions	Dec. 31, 2017 USD ($)	Jun. 30, 2017	Dec. 31, 2016 USD ($)
Successor
Coal Trading [Line Items]
Number of major credit rating agencies that adjusted corporate credit rating	1	2
Coal Trading [Member]
Coal Trading [Line Items]
Receivables from Brokers-Dealers and Clearing Organizations			$ 2.0
Coal Trading [Member] \| Predecessor
Coal Trading [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net			57.4
Derivative, Collateral, Right to Reclaim Cash			16.2
Potential collateralization that may be requested by counterparties due to a material adverse event			2.0
Margin posted to counterparties related to credit rating			$ 1.0
Coal Trading [Member] \| Successor
Coal Trading [Line Items]
Additional potential collateral requirements for a credit downgrade	$ 0.0
Receivables from Brokers-Dealers and Clearing Organizations	1.8
Derivative, Fair Value, Amount Offset Against Collateral, Net	35.8
Derivative, Collateral, Right to Reclaim Cash	18.8
Potential collateralization that may be requested by counterparties due to a material adverse event	7.0
Margin Posted To Counterparties Related To Material Adverse Event	0.4
Margin posted to counterparties related to credit rating	$ 0.0
External Credit Rating, Investment Grade [Member] \| Coal Trading [Member] \| Credit Concentration Risk [Member] \| Coal Trading Positions [Member] \| Successor
Coal Trading [Line Items]
Credit Exposure Related to Coal Trading Activities	71.00%
Non Rated [Member] \| Coal Trading [Member] \| Credit Concentration Risk [Member] \| Coal Trading Positions [Member] \| Successor
Coal Trading [Line Items]
Credit Exposure Related to Coal Trading Activities	29.00%