COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Potsdam (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Accrual for Environmental Loss Contingencies [Roll Forward]
Ending balance	$ 11,694
Potsdam Environmental Remediation Liability
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5,866	$ 5,221
Payments	(108)	(255)
Obligations incurred	0	900
Ending balance	$ 5,758	$ 5,866

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Amount of expense for newly incurred environmental loss contingencies. Includes, but is not limited to, remediation expense and interest accretion.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount of cash outflow to settle environmental loss contingencies.

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