Number of crew deaths resulting from the dredge fire.

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The number of gallons of oil, diesel fuel, and contaminated water discharged during the fire.

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Number of lawsuits filed against the entity.

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Amount of increase in allowance for credit loss on accounts receivable, from recovery.

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Amount, after allowance for credit loss, of financing receivable, classified as current. Includes, but is not limited to, notes and loan receivable.

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Amount, after allowance for credit loss, of financing receivable, classified as noncurrent.

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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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Cash received for the settlement of litigation during the current period.

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Disclosure of the unamortized amount of the discount on the note or receivable which is deducted from the face amount of the receivable or loan. The discount or premium is the difference between the present value and the face amount.

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Commitments and Contingencies - Narrative (Details) $ in Millions		3 Months Ended
	Aug. 21, 2020 item gal	Sep. 30, 2020 USD ($) lawsuit	Mar. 31, 2018 USD ($)
Other Commitments [Line Items]
Recovery of reserved accounts receivable		$ 0.9
Settled Litigation
Other Commitments [Line Items]
Legal settlement			$ 5.5
Notes receivable, current		0.8
Notes receivables, noncurrent		2.0
Receivable, unamortized discount		$ 0.2
Waymon L Boyd Dredge Fire
Other Commitments [Line Items]
Number of crew deaths \| item	4
Number of gallons of oil, diesel fuel, and contaminated water discharged \| gal	18,000
Waymon L Boyd Dredge Fire \| Pending Litigation
Other Commitments [Line Items]
Number of lawsuits filed \| lawsuit		7