Amount of cash outflow to settle environmental loss contingencies.

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Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

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Estimate of reasonably possible loss exposure in excess of amount accrued for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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

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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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Amount of loss contingency liability.

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Number of claims settled.

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Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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Commitments and Contingencies (Additional Information) (Detail) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Oct. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) settlement	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2016 USD ($)	Jun. 17, 2015 USD ($)
Environmental Loss Contingencies [Line Items]
Environmental Loss contingency accrual		$ 47,409			$ 48,817
Equity Method Investment, Ownership Percentage		100.00%
Pending Litigation [Member]
Environmental Loss Contingencies [Line Items]
Maximum Expected Damages	$ 167
LDEQ [Member] \| Settled Litigation [Member]
Environmental Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party		$ 192
Number of claims settled \| settlement		2
LDEQ [Member] \| Pending Litigation [Member]
Environmental Loss Contingencies [Line Items]
Maximum Expected Damages		$ 100
Natrium [Member] \| Axiall Corporation [Member] \| Settled Litigation [Member]
Environmental Loss Contingencies [Line Items]
Payments for environmental loss contingencies				$ 449
Lake Charles, Louisiana [Member] \| Axiall Corporation [Member] \| Environmental Protection Agency [Member] \| Settled Litigation [Member]
Environmental Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party			$ 878
Maximum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss		80,000
Minimum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss		40,000
Unfavorable Regulatory Action [Member] \| Culvert City, Kentucky and Lakes Charles, Louisiana [Member] \| Environmental Protection Agency [Member] \| Pending Litigation [Member]
Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		100
Affiliated Entity [Member] \| LACC [Member]
Environmental Loss Contingencies [Line Items]
Due to Affiliate						$ 225,000
Equity Method Investment, Ownership Percentage						10.00%
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		$ 106,405