Discontinued Operations - Summary of Discontinued Operations included in Consolidated Statements of Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Non-operating income (expense)
Income (loss) before income taxes	$ 544	$ 1,284	$ (207,242)
Income tax provision (benefit)	29	(2,386)	(30,086)
Income (loss) from discontinued operations	515	3,670	(177,156)
Specialty Papers [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues			664,574
Costs of products sold			637,472
Gross profit			27,102
Selling, general and administrative expenses	(544)	109	32,465
(Gains) losses on dispositions of plant, equipment and timberlands, net			(423)
Operating income (loss)	544	(109)	(4,940)
Non-operating income (expense)
Interest expense			(6,942)
Other, net		1,393	(51,236)
Impairment charge		(144,100)	(144,124)
Income (loss) before income taxes	544	1,284	(207,242)
Income tax provision (benefit)	29	(2,386)	(30,086)
Income (loss) from discontinued operations	$ 515	$ 3,670	(177,156)
Specialty Papers [Member] | Product [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues			661,186
Specialty Papers [Member] | Energy and Related Sales Net [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues			$ 3,388