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Commitments, Contingencies and Legal Proceedings - Additional Information (Detail) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jan. 31, 2019 USD ($) | Mar. 31, 2020 USD ($) Operable_Unit | Dec. 31, 2019 USD ($)
Commitments Contingencies And Litigation [Line Items] |  |  |
Number of operable units | Operable_Unit |  | 5 |
Term of agreement with third party for monitoring and maintenance in OU1-OU4a |  | 30 years |
Difference recorded in escrow account |  | $ 1,800 |
Total amount available in escrow account |  | 9,000 |
Reserve for Environmental liabilities, current portion |  | 8,000 | $ 9,000
Other Long-Term Liabilities [Member] |  |  |
Commitments Contingencies And Litigation [Line Items] |  |  |
Reserve for Environmental liabilities, remaining portion |  | $ 13,800 |
Minimum [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] |  |  |
Payments for governments unreimbursed past costs | $ 20,500 |  | $ 20,500
OU2-5 [Member] |  |  |
Commitments Contingencies And Litigation [Line Items] |  |  |
Expected cleanup work continuation year |  | through 2020 |

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