Commitments and Contingencies (Additional Information) (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) settlement	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)
Loss Contingencies [Line Items]
Loss contingency accrual	$ 60,693	$ 1,095
Settled Litigation [Member]
Loss Contingencies [Line Items]
Payments for environmental loss contingencies			$ 449
Number of claims settled | settlement	2
Amount of settlement for compliance violations	$ 192
Pending Litigation [Member]
Loss Contingencies [Line Items]
Damages sought	167
LDEQ [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Damages sought	$ 100
Axiall Corporation [Member] | Settled Litigation [Member]
Loss Contingencies [Line Items]
Amount of settlement for compliance violations		$ 900