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Commitments, Contingencies and Legal Proceedings - Additional Information (Detail) $ in Thousands | 9 Months Ended |
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Sep. 30, 2019 USD ($) Operable_Unit | Dec. 31, 2018 USD ($)
Commitments Contingencies And Litigation [Line Items] |  |
Number of operable units | Operable_Unit | 5 |
Term of agreement wih third party for monitoring and maintenance in OU1-OU4a | 30 years |
Difference recorded in escrow account | $ 2,000 |
Reserve for Environmental liabilities, current portion | 7,700 | $ 23,000
Reserve adjustment | (2,509) |
Selling, General and Administrative Expense [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Reserve adjustment | 2,500 |
Other Long-Term Liabilities [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Reserve for Environmental liabilities, remaining portion | $ 14,200 |
Minimum [Member] | December 2009 - Long Term Monitoring Plan [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Period over which cash expenditure to be incurred for monitoring activities | 30 years |
Glatfelter Consent Decree [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Governments unreimbursed past costs paid | $ 20,500 |
Georgia Pacific [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Settlement payable amount | $ 9,500 |
Payment due date | 2017-08 |
OU2-5 [Member] |  |
Commitments Contingencies And Litigation [Line Items] |  |
Expected cleanup work continuation year | through 2019 |

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