Commitments, Contingencies and Legal Proceedings - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 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	5,047	$ 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	$ 17,000
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