Bad Debt on Physical Coal [Abstract]

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- Definition

Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
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- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

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The amount of cash paid for the settlement of litigation or for other legal issues during the period.

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- Definition

Amount of expense related to other loss.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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-Name Accounting Standards Codification
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Bad Debt on Physical Coal (Details) - USD ($)	3 Months Ended								12 Months Ended
Bad Debt on Physical Coal (Details) - USD ($)	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Bad Debt on Physical Coal [Abstract]
(Recovery) bad debt on physical coal	$ (10,000,000)	$ 0	$ 0	$ (2,400,000)	$ 0	$ 0	$ 0	$ 1,000,000	$ (12,400,000.0)	$ 1,000,000.0	$ 47,000,000.0
Payments for Legal Settlements									8,400,000
Gain (Loss) Related to Litigation Settlement									2,400,000
Insurance Recoveries									$ 10,000,000